#[cfg(feature = "use-dyn-lib")]
use {crate::LIB, std::ffi::CStr};

use super::*;
use crate::{
    block::block_from_structure,
    column::ColInfo,
    site2::util::Dir,
    util::{RandomField, Sampler},
    CanvasInfo, ColumnSample,
};
use common::{
    generation::EntityInfo,
    store::{Id, Store},
    terrain::{
        structure::{Structure as PrefabStructure, StructureBlock},
        Block, BlockKind, SpriteCfg,
    },
    vol::ReadVol,
};
use num::cast::AsPrimitive;
use std::{
    cell::RefCell,
    f32::consts::{PI, TAU},
    ops::RangeBounds,
    sync::Arc,
};
use vek::*;

#[allow(dead_code)]
pub enum Primitive {
    Empty, // Placeholder

    // Shapes
    Aabb(Aabb<i32>),
    Pyramid {
        aabb: Aabb<i32>,
        inset: i32,
    },
    Ramp {
        aabb: Aabb<i32>,
        inset: i32,
        dir: Dir,
    },
    Gable {
        aabb: Aabb<i32>,
        inset: i32,
        // X axis parallel or Y axis parallel
        dir: Dir,
    },
    Cylinder(Aabb<i32>),
    Cone(Aabb<i32>),
    Sphere(Aabb<i32>),
    /// An Aabb with rounded corners. The degree relates to how rounded the
    /// corners are. A value less than 1.0 results in concave faces. A value
    /// of 2.0 results in an ellipsoid. Values greater than 2.0 result in a
    /// rounded aabb. Values less than 0.0 are clamped to 0.0 as negative values
    /// would theoretically yield shapes extending to infinity.
    Superquadric {
        aabb: Aabb<i32>,
        degree: f32,
    },
    Plane(Aabr<i32>, Vec3<i32>, Vec2<f32>),
    /// A line segment from start to finish point with a given radius for both
    /// points
    Segment {
        segment: LineSegment3<f32>,
        r0: f32,
        r1: f32,
    },
    /// A prism created by projecting a line segment with a given radius along
    /// the z axis up to a provided height
    SegmentPrism {
        segment: LineSegment3<f32>,
        radius: f32,
        height: f32,
    },
    /// A sampling function is always a subset of another primitive to avoid
    /// needing infinite bounds
    Sampling(Id<Primitive>, Box<dyn Fn(Vec3<i32>) -> bool>),
    ColSampling(Id<Primitive>, Box<dyn Fn(Vec3<i32>, &ColInfo) -> bool>),
    Prefab(Box<PrefabStructure>),

    // Combinators
    Intersect(Id<Primitive>, Id<Primitive>),
    Union(Id<Primitive>, Id<Primitive>),
    // Not commutative
    Without(Id<Primitive>, Id<Primitive>),
    // Operators
    Translate(Id<Primitive>, Vec3<i32>),
    Scale(Id<Primitive>, Vec3<f32>),
    RotateAbout(Id<Primitive>, Mat3<i32>, Vec3<f32>),
    /// Repeat a primitive a number of times in a given direction, overlapping
    /// between repeats are unspecified.
    Repeat(Id<Primitive>, Vec3<i32>, u32),
}

impl std::fmt::Debug for Primitive {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        match self {
            Primitive::Empty => f.debug_tuple("Empty").finish(),
            Primitive::Aabb(aabb) => f.debug_tuple("Aabb").field(&aabb).finish(),
            Primitive::Pyramid { aabb, inset } => {
                f.debug_tuple("Pyramid").field(&aabb).field(&inset).finish()
            },
            Primitive::Ramp { aabb, inset, dir } => f
                .debug_tuple("Ramp")
                .field(&aabb)
                .field(&inset)
                .field(&dir)
                .finish(),
            Primitive::Gable { aabb, inset, dir } => f
                .debug_tuple("Gable")
                .field(&aabb)
                .field(&inset)
                .field(&dir)
                .finish(),
            Primitive::Cylinder(aabb) => f.debug_tuple("Cylinder").field(&aabb).finish(),
            Primitive::Cone(aabb) => f.debug_tuple("Cone").field(&aabb).finish(),
            Primitive::Sphere(aabb) => f.debug_tuple("Sphere").field(&aabb).finish(),
            Primitive::Superquadric { aabb, degree } => f
                .debug_tuple("Superquadric")
                .field(&aabb)
                .field(&degree)
                .finish(),
            Primitive::Plane(aabr, origin, gradient) => f
                .debug_tuple("Plane")
                .field(&aabr)
                .field(&origin)
                .field(&gradient)
                .finish(),
            Primitive::Segment { segment, r0, r1 } => f
                .debug_tuple("Segment")
                .field(&segment)
                .field(&r0)
                .field(&r1)
                .finish(),
            Primitive::SegmentPrism {
                segment,
                radius,
                height,
            } => f
                .debug_tuple("SegmentPrism")
                .field(&segment)
                .field(&radius)
                .field(&height)
                .finish(),
            Primitive::Sampling(prim, _) => f.debug_tuple("Sampling").field(&prim).finish(),
            Primitive::ColSampling(prim, _) => f.debug_tuple("ColSampling").field(&prim).finish(),
            Primitive::Prefab(prefab) => f.debug_tuple("Prefab").field(&prefab).finish(),
            Primitive::Intersect(a, b) => f.debug_tuple("Intersect").field(&a).field(&b).finish(),
            Primitive::Union(a, b) => f.debug_tuple("Union").field(&a).field(&b).finish(),
            Primitive::Without(a, b) => f.debug_tuple("Without").field(&a).field(&b).finish(),
            Primitive::Translate(a, vec) => {
                f.debug_tuple("Translate").field(&a).field(&vec).finish()
            },
            Primitive::Scale(a, vec) => f.debug_tuple("Scale").field(&a).field(&vec).finish(),
            Primitive::RotateAbout(a, mat, vec) => f
                .debug_tuple("RotateAbout")
                .field(&a)
                .field(&mat)
                .field(&vec)
                .finish(),
            Primitive::Repeat(a, offset, n) => f
                .debug_tuple("Repeat")
                .field(&a)
                .field(&offset)
                .field(&n)
                .finish(),
        }
    }
}

impl Primitive {
    pub fn intersect(a: impl Into<Id<Primitive>>, b: impl Into<Id<Primitive>>) -> Self {
        Self::Intersect(a.into(), b.into())
    }

    pub fn union(a: impl Into<Id<Primitive>>, b: impl Into<Id<Primitive>>) -> Self {
        Self::Union(a.into(), b.into())
    }

    pub fn without(a: impl Into<Id<Primitive>>, b: impl Into<Id<Primitive>>) -> Self {
        Self::Without(a.into(), b.into())
    }

    pub fn sampling(a: impl Into<Id<Primitive>>, f: Box<dyn Fn(Vec3<i32>) -> bool>) -> Self {
        Self::Sampling(a.into(), f)
    }

    pub fn column_sampling(
        a: impl Into<Id<Primitive>>,
        f: Box<dyn Fn(Vec3<i32>, &ColInfo) -> bool>,
    ) -> Self {
        Self::ColSampling(a.into(), f)
    }

    pub fn translate(a: impl Into<Id<Primitive>>, trans: Vec3<i32>) -> Self {
        Self::Translate(a.into(), trans)
    }

    pub fn scale(a: impl Into<Id<Primitive>>, scale: Vec3<f32>) -> Self {
        Self::Scale(a.into(), scale)
    }

    pub fn rotate_about(
        a: impl Into<Id<Primitive>>,
        rot: Mat3<i32>,
        point: Vec3<impl AsPrimitive<f32>>,
    ) -> Self {
        Self::RotateAbout(a.into(), rot, point.as_())
    }

    /// Rotates a primitive 90 degrees CCW about the Z axis `n` times
    pub fn rotate_z_90_about(
        a: impl Into<Id<Primitive>>,
        n: i32,
        point: Vec3<impl AsPrimitive<f32>>,
    ) -> Self {
        let rot = match n % 4 {
            1 => Mat3::new(0, -1, 0, 1, 0, 0, 0, 0, 1),
            2 => Mat3::new(-1, 0, 0, 0, -1, 0, 0, 0, 1),
            3 => Mat3::new(0, 1, 0, -1, 0, 0, 0, 0, 1),
            _ => Mat3::new(1, 0, 0, 0, 1, 0, 0, 0, 1),
        };
        Self::RotateAbout(a.into(), rot, point.as_())
    }

    pub fn repeat(a: impl Into<Id<Primitive>>, offset: Vec3<i32>, count: u32) -> Self {
        Self::Repeat(a.into(), offset, count)
    }
}

#[derive(Clone)]
pub enum Fill {
    Sprite(Block),
    ResourceSprite(Block),
    CfgSprite(Block, SpriteCfg),

    Block(Block),
    Brick(BlockKind, Rgb<u8>, u8),
    Gradient(util::gradient::Gradient, BlockKind),
    // TODO: the offset field for Prefab is a hack that breaks the compositionality of Translate,
    // we probably need an evaluator for the primitive tree that gets which point is queried at
    // leaf nodes given an input point to make Translate/Rotate work generally
    Prefab(Box<PrefabStructure>, Vec3<i32>, u32),
    Sampling(Arc<dyn Fn(Vec3<i32>) -> Option<Block>>),
}

impl Fill {
    pub fn sprite(kind: SpriteKind) -> Self { Fill::Block(Block::empty().with_sprite(kind)) }

    pub fn sprite_ori(kind: SpriteKind, ori: u8) -> Self {
        let block = Block::empty().with_sprite(kind);

        let block = block.with_ori(ori).unwrap_or(block);
        Fill::Sprite(block)
    }

    pub fn resource_sprite(kind: SpriteKind) -> Self {
        Fill::ResourceSprite(Block::empty().with_sprite(kind))
    }

    pub fn resource_sprite_ori(kind: SpriteKind, ori: u8) -> Self {
        let block = Block::empty().with_sprite(kind);

        let block = block.with_ori(ori).unwrap_or(block);
        Fill::ResourceSprite(block)
    }

    pub fn owned_resource_sprite_ori(kind: SpriteKind, ori: u8) -> Self {
        let block = Block::empty().with_sprite(kind);

        let block = block.with_ori(ori).unwrap_or(block);
        let block = block
            .with_attr(common::terrain::sprite::Owned(true))
            .unwrap_or(block);

        Fill::ResourceSprite(block)
    }

    pub fn sprite_ori_cfg(kind: SpriteKind, ori: u8, cfg: SpriteCfg) -> Self {
        let block = Block::empty().with_sprite(kind);

        let block = block.with_ori(ori).unwrap_or(block);
        Fill::CfgSprite(block, cfg)
    }

    fn contains_at(
        tree: &Store<Primitive>,
        prim: Id<Primitive>,
        pos: Vec3<i32>,
        col: &ColInfo,
    ) -> bool {
        // Custom closure because vek's impl of `contains_point` is inclusive :(
        let aabb_contains = |aabb: Aabb<i32>, pos: Vec3<i32>| {
            (aabb.min.x..aabb.max.x).contains(&pos.x)
                && (aabb.min.y..aabb.max.y).contains(&pos.y)
                && (aabb.min.z..aabb.max.z).contains(&pos.z)
        };

        match &tree[prim] {
            Primitive::Empty => false,

            Primitive::Aabb(aabb) => aabb_contains(*aabb, pos),
            Primitive::Ramp { aabb, inset, dir } => {
                let inset = (*inset).max(aabb.size().reduce_min());
                let inner = match dir {
                    Dir::X => Aabr {
                        min: Vec2::new(aabb.min.x - 1 + inset, aabb.min.y),
                        max: Vec2::new(aabb.max.x, aabb.max.y),
                    },
                    Dir::NegX => Aabr {
                        min: Vec2::new(aabb.min.x, aabb.min.y),
                        max: Vec2::new(aabb.max.x - inset, aabb.max.y),
                    },
                    Dir::Y => Aabr {
                        min: Vec2::new(aabb.min.x, aabb.min.y - 1 + inset),
                        max: Vec2::new(aabb.max.x, aabb.max.y),
                    },
                    Dir::NegY => Aabr {
                        min: Vec2::new(aabb.min.x, aabb.min.y),
                        max: Vec2::new(aabb.max.x, aabb.max.y - inset),
                    },
                };
                aabb_contains(*aabb, pos)
                    && (inner.projected_point(pos.xy()) - pos.xy())
                        .map(|e| e.abs())
                        .reduce_max() as f32
                        / (inset as f32)
                        < 1.0
                            - ((pos.z - aabb.min.z) as f32 + 0.5) / (aabb.max.z - aabb.min.z) as f32
            },
            Primitive::Pyramid { aabb, inset } => {
                let inset = (*inset).max(aabb.size().reduce_min());
                let inner = Aabr {
                    min: aabb.min.xy() - 1 + inset,
                    max: aabb.max.xy() - inset,
                };
                aabb_contains(*aabb, pos)
                    && (inner.projected_point(pos.xy()) - pos.xy())
                        .map(|e| e.abs())
                        .reduce_max() as f32
                        / (inset as f32)
                        < 1.0
                            - ((pos.z - aabb.min.z) as f32 + 0.5) / (aabb.max.z - aabb.min.z) as f32
            },
            Primitive::Gable { aabb, inset, dir } => {
                let inset = (*inset).max(aabb.size().reduce_min());
                let inner = if dir.is_y() {
                    Aabr {
                        min: Vec2::new(aabb.min.x - 1 + inset, aabb.min.y),
                        max: Vec2::new(aabb.max.x - inset, aabb.max.y),
                    }
                } else {
                    Aabr {
                        min: Vec2::new(aabb.min.x, aabb.min.y - 1 + inset),
                        max: Vec2::new(aabb.max.x, aabb.max.y - inset),
                    }
                };
                aabb_contains(*aabb, pos)
                    && (inner.projected_point(pos.xy()) - pos.xy())
                        .map(|e| e.abs())
                        .reduce_max() as f32
                        / (inset as f32)
                        < 1.0
                            - ((pos.z - aabb.min.z) as f32 + 0.5) / (aabb.max.z - aabb.min.z) as f32
            },
            Primitive::Cylinder(aabb) => {
                // Add 0.5 since the aabb is exclusive.
                let fpos = pos.as_::<f32>().xy() - aabb.as_::<f32>().center().xy() + 0.5;
                let size = Vec3::from(aabb.size().as_::<f32>()).xy();
                (aabb.min.z..aabb.max.z).contains(&pos.z)
                    && (2.0 * fpos / size).magnitude_squared() <= 1.0
            },
            Primitive::Cone(aabb) => {
                (aabb.min.z..aabb.max.z).contains(&pos.z)
                    && pos
                        .xy()
                        .as_()
                        .distance_squared(aabb.as_().center().xy() - 0.5)
                        < (((aabb.max.z - pos.z) as f32 / aabb.size().d as f32)
                            * (aabb.size().w.min(aabb.size().h) as f32 / 2.0))
                            .powi(2)
            },
            Primitive::Sphere(aabb) => {
                aabb_contains(*aabb, pos)
                    && pos.as_().distance_squared(aabb.as_().center() - 0.5)
                        < (aabb.size().w.min(aabb.size().h) as f32 / 2.0).powi(2)
            },
            Primitive::Superquadric { aabb, degree } => {
                let degree = degree.max(0.0);
                let center = aabb.center().map(|e| e as f32);
                let a: f32 = aabb.max.x as f32 - center.x - 0.5;
                let b: f32 = aabb.max.y as f32 - center.y - 0.5;
                let c: f32 = aabb.max.z as f32 - center.z - 0.5;
                let rpos = pos.as_::<f32>() + 0.5 - center;
                aabb_contains(*aabb, pos)
                    && (rpos.x / a).abs().powf(degree)
                        + (rpos.y / b).abs().powf(degree)
                        + (rpos.z / c).abs().powf(degree)
                        < 1.0
            },
            Primitive::Plane(aabr, origin, gradient) => {
                // Maybe <= instead of ==
                (aabr.min.x..aabr.max.x).contains(&pos.x)
                    && (aabr.min.y..aabr.max.y).contains(&pos.y)
                    && pos.z
                        == origin.z
                            + ((pos.xy() - origin.xy())
                                .map(|x| x.abs())
                                .as_()
                                .dot(*gradient) as i32)
            },
            // TODO: Aabb calculation could be improved here by only considering the relevant radius
            Primitive::Segment { segment, r0, r1 } => {
                let distance = segment.end - segment.start;
                let length = pos - segment.start.as_();
                let t =
                    (length.as_().dot(distance) / distance.magnitude_squared()).clamped(0.0, 1.0);
                segment.distance_to_point(pos.map(|e| e as f32)) < Lerp::lerp(r0, r1, t) - 0.25
            },
            Primitive::SegmentPrism {
                segment,
                radius,
                height,
            } => {
                let segment_2d = LineSegment2 {
                    start: segment.start.xy(),
                    end: segment.end.xy(),
                };
                let projected_point_2d: Vec2<f32> =
                    segment_2d.as_().projected_point(pos.xy().as_());
                let xy_check = projected_point_2d.distance(pos.xy().as_()) < radius - 0.25;
                let projected_z = {
                    let len_sq: f32 = segment_2d
                        .start
                        .as_()
                        .distance_squared(segment_2d.end.as_());
                    if len_sq < 0.1 {
                        segment.start.z
                    } else {
                        let frac = ((projected_point_2d - segment_2d.start.as_())
                            .dot(segment_2d.end.as_() - segment_2d.start.as_())
                            / len_sq)
                            .clamp(0.0, 1.0);
                        (segment.end.z - segment.start.z) * frac + segment.start.z
                    }
                };
                let z_check = (projected_z..=(projected_z + height)).contains(&(pos.z as f32));
                xy_check && z_check
            },
            Primitive::Sampling(a, f) => Self::contains_at(tree, *a, pos, col) && f(pos),
            Primitive::ColSampling(a, f) => Self::contains_at(tree, *a, pos, col) && f(pos, col),
            Primitive::Prefab(p) => !matches!(p.get(pos), Err(_) | Ok(StructureBlock::None)),
            Primitive::Intersect(a, b) => {
                Self::contains_at(tree, *a, pos, col) && Self::contains_at(tree, *b, pos, col)
            },
            Primitive::Union(a, b) => {
                Self::contains_at(tree, *a, pos, col) || Self::contains_at(tree, *b, pos, col)
            },
            Primitive::Without(a, b) => {
                Self::contains_at(tree, *a, pos, col) && !Self::contains_at(tree, *b, pos, col)
            },
            Primitive::Translate(prim, vec) => {
                Self::contains_at(tree, *prim, pos.map2(*vec, i32::saturating_sub), col)
            },
            Primitive::Scale(prim, vec) => {
                let center = Self::get_bounds(tree, *prim).as_::<f32>().center();
                let fpos = pos.as_::<f32>();
                let spos = (center + ((fpos - center) / vec))
                    .map(|x| x.round())
                    .as_::<i32>();
                Self::contains_at(tree, *prim, spos, col)
            },
            Primitive::RotateAbout(prim, mat, vec) => {
                let mat = mat.as_::<f32>().transposed();
                let vec = vec - 0.5;
                Self::contains_at(
                    tree,
                    *prim,
                    (vec + mat * (pos.as_::<f32>() - vec)).as_(),
                    col,
                )
            },
            Primitive::Repeat(prim, offset, count) => {
                if count == &0 {
                    false
                } else {
                    let count = count - 1;
                    let aabb = Self::get_bounds(tree, *prim);
                    let aabb_corner = {
                        let min_red = aabb.min.map2(*offset, |a, b| if b < 0 { 0 } else { a });
                        let max_red = aabb.max.map2(*offset, |a, b| if b < 0 { a } else { 0 });
                        min_red + max_red
                    };
                    let diff = pos - aabb_corner;
                    let min = diff
                        .map2(*offset, |a, b| if b == 0 { i32::MAX } else { a / b })
                        .reduce_min()
                        .clamp(0, count as i32);
                    let pos = pos - offset * min;
                    Self::contains_at(tree, *prim, pos, col)
                }
            },
        }
    }

    pub fn sample_at(
        &self,
        tree: &Store<Primitive>,
        prim: Id<Primitive>,
        pos: Vec3<i32>,
        canvas_info: &CanvasInfo,
        old_block: Block,
        sprite_cfg: &mut Option<SpriteCfg>,
        col: &ColInfo,
    ) -> Option<Block> {
        if Self::contains_at(tree, prim, pos, col) {
            match self {
                Fill::Sprite(sprite) | Fill::ResourceSprite(sprite) => {
                    Some(if old_block.is_filled() {
                        *sprite
                    } else {
                        old_block.with_data_of(*sprite)
                    })
                },
                Fill::CfgSprite(sprite, cfg) => {
                    *sprite_cfg = Some(cfg.clone());
                    Some(if old_block.is_filled() {
                        *sprite
                    } else {
                        old_block.with_data_of(*sprite)
                    })
                },
                Fill::Block(block) => Some(*block),
                Fill::Brick(bk, col, range) => Some(Block::new(
                    *bk,
                    *col + (RandomField::new(13)
                        .get((pos + Vec3::new(pos.z, pos.z, 0)) / Vec3::new(2, 2, 1))
                        % *range as u32) as u8,
                )),
                Fill::Gradient(gradient, bk) => Some(Block::new(*bk, gradient.sample(pos.as_()))),
                Fill::Prefab(p, tr, seed) => p.get(pos - tr).ok().and_then(|sb| {
                    let col_sample = canvas_info.col(canvas_info.wpos)?;
                    block_from_structure(
                        canvas_info.index,
                        sb,
                        pos - tr,
                        p.get_bounds().center().xy(),
                        *seed,
                        col_sample,
                        Block::air,
                        canvas_info.calendar(),
                        &Vec2::new(Vec2::new(1, 0), Vec2::new(0, 1)),
                    )
                    .map(|(block, cfg)| {
                        *sprite_cfg = cfg;
                        block
                    })
                }),
                Fill::Sampling(f) => f(pos),
            }
        } else {
            None
        }
    }

    fn get_bounds_inner(tree: &Store<Primitive>, prim: Id<Primitive>) -> Vec<Aabb<i32>> {
        fn or_zip_with<T, F: FnOnce(T, T) -> T>(a: Option<T>, b: Option<T>, f: F) -> Option<T> {
            match (a, b) {
                (Some(a), Some(b)) => Some(f(a, b)),
                (Some(a), _) => Some(a),
                (_, b) => b,
            }
        }

        match &tree[prim] {
            Primitive::Empty => vec![],
            Primitive::Aabb(aabb) => vec![*aabb],
            Primitive::Pyramid { aabb, .. } => vec![*aabb],
            Primitive::Gable { aabb, .. } => vec![*aabb],
            Primitive::Ramp { aabb, .. } => vec![*aabb],
            Primitive::Cylinder(aabb) => vec![*aabb],
            Primitive::Cone(aabb) => vec![*aabb],
            Primitive::Sphere(aabb) => vec![*aabb],
            Primitive::Superquadric { aabb, .. } => vec![*aabb],
            Primitive::Plane(aabr, origin, gradient) => {
                let half_size = aabr.half_size().reduce_max();
                let longest_dist = ((aabr.center() - origin.xy()).map(|x| x.abs())
                    + half_size
                    + aabr.size().reduce_max() % 2)
                    .map(|x| x as f32);
                let z = if gradient.x.signum() == gradient.y.signum() {
                    Vec2::new(0, longest_dist.dot(*gradient) as i32)
                } else {
                    (longest_dist * gradient).as_()
                };
                let aabb = Aabb {
                    min: aabr.min.with_z(origin.z + z.reduce_min().min(0)),
                    max: aabr.max.with_z(origin.z + z.reduce_max().max(0)),
                };
                vec![aabb.made_valid()]
            },
            Primitive::Segment { segment, r0, r1 } => {
                let aabb = Aabb {
                    min: segment.start,
                    max: segment.end,
                }
                .made_valid();
                vec![Aabb {
                    min: (aabb.min - r0.max(*r1)).floor().as_(),
                    max: (aabb.max + r0.max(*r1)).ceil().as_(),
                }]
            },
            Primitive::SegmentPrism {
                segment,
                radius,
                height,
            } => {
                let aabb = Aabb {
                    min: segment.start,
                    max: segment.end,
                }
                .made_valid();
                let min = {
                    let xy = (aabb.min.xy() - *radius).floor();
                    xy.with_z(aabb.min.z).as_()
                };
                let max = {
                    let xy = (aabb.max.xy() + *radius).ceil();
                    xy.with_z((aabb.max.z + *height).ceil()).as_()
                };
                vec![Aabb { min, max }]
            },
            Primitive::Sampling(a, _) | Primitive::ColSampling(a, _) => {
                Self::get_bounds_inner(tree, *a)
            },
            Primitive::Prefab(p) => vec![p.get_bounds()],
            Primitive::Intersect(a, b) => or_zip_with(
                Self::get_bounds_opt(tree, *a),
                Self::get_bounds_opt(tree, *b),
                |a, b| a.intersection(b),
            )
            .into_iter()
            .collect(),

            Primitive::Union(a, b) => {
                fn jaccard(x: Aabb<i32>, y: Aabb<i32>) -> f32 {
                    let s_intersection = x.intersection(y).size().as_::<f32>().magnitude();
                    let s_union = x.union(y).size().as_::<f32>().magnitude();
                    s_intersection / s_union
                }
                let mut inputs = Vec::new();
                inputs.extend(Self::get_bounds_inner(tree, *a));
                inputs.extend(Self::get_bounds_inner(tree, *b));
                let mut results = Vec::new();
                if let Some(aabb) = inputs.pop() {
                    results.push(aabb);
                    for a in &inputs {
                        let best = results
                            .iter()
                            .enumerate()
                            .max_by_key(|(_, b)| (jaccard(*a, **b) * 1000.0) as usize);
                        match best {
                            Some((i, b)) if jaccard(*a, *b) > 0.3 => {
                                let mut aabb = results.swap_remove(i);
                                aabb = aabb.union(*a);
                                results.push(aabb);
                            },
                            _ => results.push(*a),
                        }
                    }
                    results
                } else {
                    results
                }
            },
            Primitive::Without(a, _) => Self::get_bounds_inner(tree, *a),
            Primitive::Translate(prim, vec) => Self::get_bounds_inner(tree, *prim)
                .into_iter()
                .map(|aabb| Aabb {
                    min: aabb.min.map2(*vec, i32::saturating_add),
                    max: aabb.max.map2(*vec, i32::saturating_add),
                })
                .collect(),
            Primitive::Scale(prim, vec) => Self::get_bounds_inner(tree, *prim)
                .into_iter()
                .map(|aabb| {
                    let center = aabb.center();
                    Aabb {
                        min: center + ((aabb.min - center).as_::<f32>() * vec).as_::<i32>(),
                        max: center + ((aabb.max - center).as_::<f32>() * vec).as_::<i32>(),
                    }
                })
                .collect(),
            Primitive::RotateAbout(prim, mat, vec) => Self::get_bounds_inner(tree, *prim)
                .into_iter()
                .map(|aabb| {
                    let mat = mat.as_::<f32>();
                    // - 0.5 because we want the point to be at the minimum of the voxel
                    let vec = vec - 0.5;
                    let new_aabb = Aabb::<f32> {
                        min: vec + mat * (aabb.min.as_() - vec),
                        // - 1 becuase we want the AABB to be inclusive when we rotate it, we then
                        //   add 1 back to make it exclusive again
                        max: vec + mat * ((aabb.max - 1).as_() - vec),
                    }
                    .made_valid();
                    Aabb::<i32> {
                        min: new_aabb.min.as_(),
                        max: new_aabb.max.as_() + 1,
                    }
                })
                .collect(),
            Primitive::Repeat(prim, offset, count) => {
                if count == &0 {
                    vec![]
                } else {
                    let count = count - 1;
                    Self::get_bounds_inner(tree, *prim)
                        .into_iter()
                        .map(|aabb| Aabb {
                            min: aabb
                                .min
                                .map2(aabb.min + offset * count as i32, |a, b| a.min(b)),
                            max: aabb
                                .max
                                .map2(aabb.max + offset * count as i32, |a, b| a.max(b)),
                        })
                        .collect()
                }
            },
        }
    }

    pub fn get_bounds_disjoint(tree: &Store<Primitive>, prim: Id<Primitive>) -> Vec<Aabb<i32>> {
        Self::get_bounds_inner(tree, prim)
    }

    pub fn get_bounds_opt(tree: &Store<Primitive>, prim: Id<Primitive>) -> Option<Aabb<i32>> {
        Self::get_bounds_inner(tree, prim)
            .into_iter()
            .reduce(|a, b| a.union(b))
    }

    pub fn get_bounds(tree: &Store<Primitive>, prim: Id<Primitive>) -> Aabb<i32> {
        Self::get_bounds_opt(tree, prim).unwrap_or_else(|| Aabb::new_empty(Vec3::zero()))
    }
}

pub struct Painter {
    prims: RefCell<Store<Primitive>>,
    fills: RefCell<Vec<(Id<Primitive>, Fill)>>,
    entities: RefCell<Vec<EntityInfo>>,
    render_area: Aabr<i32>,
}

impl Painter {
    /// Computes the depth of the tree rooted at `prim`
    pub fn depth(&self, prim: Id<Primitive>) -> usize {
        fn aux(prims: &Store<Primitive>, prim: Id<Primitive>, prev_depth: usize) -> usize {
            match prims[prim] {
                Primitive::Empty
                | Primitive::Aabb(_)
                | Primitive::Pyramid { .. }
                | Primitive::Ramp { .. }
                | Primitive::Gable { .. }
                | Primitive::Cylinder(_)
                | Primitive::Cone(_)
                | Primitive::Sphere(_)
                | Primitive::Superquadric { .. }
                | Primitive::Plane(_, _, _)
                | Primitive::Segment { .. }
                | Primitive::SegmentPrism { .. }
                | Primitive::Prefab(_) => prev_depth,
                Primitive::Sampling(a, _)
                | Primitive::ColSampling(a, _)
                | Primitive::Translate(a, _)
                | Primitive::Scale(a, _)
                | Primitive::RotateAbout(a, _, _)
                | Primitive::Repeat(a, _, _) => aux(prims, a, 1 + prev_depth),

                Primitive::Intersect(a, b) | Primitive::Union(a, b) | Primitive::Without(a, b) => {
                    aux(prims, a, 1 + prev_depth).max(aux(prims, b, 1 + prev_depth))
                },
            }
        }
        let prims = self.prims.borrow();
        aux(&prims, prim, 0)
    }

    /// Orders two primitives by depth, since (A && (B && C)) is cheaper to
    /// evaluate than ((A && B) && C) due to short-circuiting.
    pub fn order_by_depth(
        &self,
        a: impl Into<Id<Primitive>>,
        b: impl Into<Id<Primitive>>,
    ) -> (Id<Primitive>, Id<Primitive>) {
        let (a, b) = (a.into(), b.into());
        if self.depth(a) < self.depth(b) {
            (a, b)
        } else {
            (b, a)
        }
    }

    /// Returns a `PrimitiveRef` of an axis aligned bounding box. The geometric
    /// name of this shape is a "right rectangular prism."
    pub fn aabb(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        self.prim(Primitive::Aabb(aabb.made_valid()))
    }

    /// Returns a `PrimitiveRef` of a sphere using a radius check.
    pub fn sphere(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        self.prim(Primitive::Sphere(aabb.made_valid()))
    }

    /// Returns a `PrimitiveRef` of a sphere using a radius check where a radius
    /// and origin are parameters instead of a bounding box.
    pub fn sphere_with_radius(&self, origin: Vec3<i32>, radius: f32) -> PrimitiveRef {
        let min = origin - Vec3::broadcast(radius.round() as i32);
        let max = origin + Vec3::broadcast(radius.round() as i32);
        self.prim(Primitive::Sphere(Aabb { min, max }))
    }

    /// Returns a `PrimitiveRef` of a sphere by returning an ellipsoid with
    /// congruent legs. The voxel artifacts are slightly different from the
    /// radius check `sphere()` method.
    pub fn sphere2(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        let radius = aabb.size().w.min(aabb.size().h) / 2;
        let aabb = Aabb {
            min: aabb.center() - radius,
            max: aabb.center() + radius,
        };
        let degree = 2.0;
        self.prim(Primitive::Superquadric { aabb, degree })
    }

    /// Returns a `PrimitiveRef` of an ellipsoid by constructing a superquadric
    /// with a degree value of 2.0.
    pub fn ellipsoid(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        let degree = 2.0;
        self.prim(Primitive::Superquadric { aabb, degree })
    }

    /// Returns a `PrimitiveRef` of a superquadric. A superquadric can be
    /// thought of as a rounded Aabb where the degree determines how rounded
    /// the corners are. Values from 0.0 to 1.0 produce concave faces or
    /// "inverse rounded corners." A value of 1.0 produces a stretched
    /// octahedron (or a non-stretched octahedron if the provided Aabb is a
    /// cube). Values from 1.0 to 2.0 produce an octahedron with convex
    /// faces. A degree of 2.0 produces an ellipsoid. Values larger than 2.0
    /// produce a rounded Aabb. The degree cannot be less than 0.0 without
    /// the shape extending to infinity.
    pub fn superquadric(&self, aabb: Aabb<i32>, degree: f32) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        self.prim(Primitive::Superquadric { aabb, degree })
    }

    /// Returns a `PrimitiveRef` of a rounded Aabb by producing a superquadric
    /// with a degree value of 3.0.
    pub fn rounded_aabb(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        self.prim(Primitive::Superquadric { aabb, degree: 3.0 })
    }

    /// Returns a `PrimitiveRef` of the largest cylinder that fits in the
    /// provided Aabb.
    pub fn cylinder(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        self.prim(Primitive::Cylinder(aabb.made_valid()))
    }

    /// Returns a `PrimitiveRef` of the largest horizontal cylinder that fits in
    /// the provided Aabb.
    pub fn horizontal_cylinder(&self, aabb: Aabb<i32>, dir: Dir) -> PrimitiveRef {
        let aabr = Aabr::from(aabb);
        let length = dir.select(aabr.size());
        let height = aabb.max.z - aabb.min.z;
        let aabb = Aabb {
            min: (aabr.min - dir.abs().to_vec2() * height).with_z(aabb.min.z),
            max: (dir.abs().select_with(aabr.min, aabr.max)).with_z(aabb.min.z + length),
        };
        self.cylinder(aabb)
            .rotate_about((-dir.abs()).from_z_mat3(), aabr.min.with_z(aabb.min.z))
    }

    /// Returns a `PrimitiveRef` of a cylinder using a radius check where a
    /// radius and origin are parameters instead of a bounding box.
    pub fn cylinder_with_radius(
        &self,
        origin: Vec3<i32>,
        radius: f32,
        height: f32,
    ) -> PrimitiveRef {
        let min = origin - Vec2::broadcast(radius.round() as i32);
        let max = origin + Vec2::broadcast(radius.round() as i32).with_z(height.round() as i32);
        self.prim(Primitive::Cylinder(Aabb { min, max }))
    }

    /// Returns a `PrimitiveRef` of the largest cone that fits in the
    /// provided Aabb.
    pub fn cone(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        self.prim(Primitive::Cone(aabb.made_valid()))
    }

    /// Returns a `PrimitiveRef` of a cone using a radius check where a radius
    /// and origin are parameters instead of a bounding box.
    pub fn cone_with_radius(&self, origin: Vec3<i32>, radius: f32, height: f32) -> PrimitiveRef {
        let min = origin - Vec2::broadcast(radius.round() as i32);
        let max = origin + Vec2::broadcast(radius.round() as i32).with_z(height.round() as i32);
        self.prim(Primitive::Cone(Aabb { min, max }))
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional line segment with a provided
    /// radius.
    pub fn line(
        &self,
        a: Vec3<impl AsPrimitive<f32>>,
        b: Vec3<impl AsPrimitive<f32>>,
        radius: f32,
    ) -> PrimitiveRef {
        self.prim(Primitive::Segment {
            segment: LineSegment3 {
                start: a.as_(),
                end: b.as_(),
            },
            r0: radius,
            r1: radius,
        })
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional line segment with two
    /// radius.
    pub fn line_two_radius(
        &self,
        a: Vec3<impl AsPrimitive<f32>>,
        b: Vec3<impl AsPrimitive<f32>>,
        r0: f32,
        r1: f32,
    ) -> PrimitiveRef {
        self.prim(Primitive::Segment {
            segment: LineSegment3 {
                start: a.as_(),
                end: b.as_(),
            },
            r0,
            r1,
        })
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional line segment where the
    /// provided radius only affects the width of the shape. The height of
    /// the shape is determined by the `height` parameter. The height of the
    /// shape is extended upwards along the z axis from the line. The top and
    /// bottom of the shape are planar and parallel to each other and the line.
    pub fn segment_prism(
        &self,
        a: Vec3<impl AsPrimitive<f32>>,
        b: Vec3<impl AsPrimitive<f32>>,
        radius: f32,
        height: f32,
    ) -> PrimitiveRef {
        let segment = LineSegment3 {
            start: a.as_(),
            end: b.as_(),
        };
        self.prim(Primitive::SegmentPrism {
            segment,
            radius,
            height,
        })
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional cubic bezier curve by
    /// dividing the curve into line segments with one segment approximately
    /// every length of 5 blocks.
    pub fn cubic_bezier(
        &self,
        start: Vec3<impl AsPrimitive<f32>>,
        ctrl0: Vec3<impl AsPrimitive<f32>>,
        ctrl1: Vec3<impl AsPrimitive<f32>>,
        end: Vec3<impl AsPrimitive<f32>>,
        radius: f32,
    ) -> PrimitiveRef {
        let bezier = CubicBezier3 {
            start: start.as_(),
            ctrl0: ctrl0.as_(),
            ctrl1: ctrl1.as_(),
            end: end.as_(),
        };
        let length = bezier.length_by_discretization(10);
        let num_segments = (0.2 * length).ceil() as u16;
        self.cubic_bezier_with_num_segments(bezier, radius, num_segments)
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional cubic bezier curve by
    /// dividing the curve into `num_segments` line segments.
    pub fn cubic_bezier_with_num_segments(
        &self,
        bezier: CubicBezier3<f32>,
        radius: f32,
        num_segments: u16,
    ) -> PrimitiveRef {
        let mut bezier_prim = self.empty();
        let range: Vec<_> = (0..=num_segments).collect();
        range.windows(2).for_each(|w| {
            let segment_start = bezier.evaluate(w[0] as f32 / num_segments as f32);
            let segment_end = bezier.evaluate(w[1] as f32 / num_segments as f32);
            bezier_prim = bezier_prim.union(self.line(segment_start, segment_end, radius));
        });
        bezier_prim
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional cubic bezier curve where the
    /// radius only governs the width of the curve. The height is governed
    /// by the `height` parameter where the shape extends upwards from the
    /// bezier curve by the value of `height`. The shape is constructed by
    /// dividing the curve into line segment prisms with one segment prism
    /// approximately every length of 5 blocks.
    pub fn cubic_bezier_prism(
        &self,
        start: Vec3<impl AsPrimitive<f32>>,
        ctrl0: Vec3<impl AsPrimitive<f32>>,
        ctrl1: Vec3<impl AsPrimitive<f32>>,
        end: Vec3<impl AsPrimitive<f32>>,
        radius: f32,
        height: f32,
    ) -> PrimitiveRef {
        let bezier = CubicBezier3 {
            start: start.as_(),
            ctrl0: ctrl0.as_(),
            ctrl1: ctrl1.as_(),
            end: end.as_(),
        };
        let length = bezier.length_by_discretization(10);
        let num_segments = (0.2 * length).ceil() as u16;
        self.cubic_bezier_prism_with_num_segments(bezier, radius, height, num_segments)
    }

    /// Returns a `PrimitiveRef` of a 3-dimensional cubic bezier curve where the
    /// radius only governs the width of the curve. The height is governed
    /// by the `height` parameter where the shape extends upwards from the
    /// bezier curve by the value of `height`. The shape is constructed by
    /// dividing the curve into `num_segments` line segment prisms.
    pub fn cubic_bezier_prism_with_num_segments(
        &self,
        bezier: CubicBezier3<f32>,
        radius: f32,
        height: f32,
        num_segments: u16,
    ) -> PrimitiveRef {
        let mut bezier_prim = self.empty();
        let range: Vec<_> = (0..=num_segments).collect();
        range.windows(2).for_each(|w| {
            let segment_start = bezier.evaluate(w[0] as f32 / num_segments as f32);
            let segment_end = bezier.evaluate(w[1] as f32 / num_segments as f32);
            bezier_prim =
                bezier_prim.union(self.segment_prism(segment_start, segment_end, radius, height));
        });
        bezier_prim
    }

    /// Returns a `PrimitiveRef` of a plane. The Aabr provides the bounds for
    /// the plane in the xy plane and the gradient determines its slope through
    /// the dot product. A gradient of <1.0, 0.0> creates a plane with a
    /// slope of 1.0 in the xz plane.
    pub fn plane(&self, aabr: Aabr<i32>, origin: Vec3<i32>, gradient: Vec2<f32>) -> PrimitiveRef {
        let aabr = aabr.made_valid();
        self.prim(Primitive::Plane(aabr, origin, gradient))
    }

    /// Returns a `PrimitiveRef` of an Aabb with a slope cut into it. The
    /// `inset` governs the slope. The `dir` determines which direction the
    /// ramp points.
    pub fn ramp_inset(&self, aabb: Aabb<i32>, inset: i32, dir: Dir) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        self.prim(Primitive::Ramp { aabb, inset, dir })
    }

    pub fn ramp(&self, aabb: Aabb<i32>, dir: Dir) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        self.prim(Primitive::Ramp {
            aabb,
            inset: dir.select((aabb.size().w, aabb.size().h)),
            dir,
        })
    }

    /// Returns a `PrimitiveRef` of a triangular prism with the base being
    /// vertical. A gable is a tent shape. The `inset` governs the slope of
    /// the gable. The `dir` determines which way the gable points.
    pub fn gable(&self, aabb: Aabb<i32>, inset: i32, dir: Dir) -> PrimitiveRef {
        let aabb = aabb.made_valid();
        self.prim(Primitive::Gable { aabb, inset, dir })
    }

    /// Places a sprite at the provided location with the default rotation.
    pub fn sprite(&self, pos: Vec3<i32>, sprite: SpriteKind) {
        self.aabb(Aabb {
            min: pos,
            max: pos + 1,
        })
        .fill(Fill::sprite(sprite))
    }

    /// Places a sprite at the provided location with the provided orientation.
    pub fn rotated_sprite(&self, pos: Vec3<i32>, sprite: SpriteKind, ori: u8) {
        self.aabb(Aabb {
            min: pos,
            max: pos + 1,
        })
        .fill(Fill::sprite_ori(sprite, ori))
    }

    /// Places a sprite at the provided location with the provided orientation
    /// and the provided [`SpriteCfg`].
    pub fn rotated_sprite_with_cfg(
        &self,
        pos: Vec3<i32>,
        sprite: SpriteKind,
        ori: u8,
        cfg: SpriteCfg,
    ) {
        self.aabb(Aabb {
            min: pos,
            max: pos + 1,
        })
        .fill(Fill::sprite_ori_cfg(sprite, ori, cfg))
    }

    /// Places a sprite at the provided location with the provided orientation
    /// which will be tracked by rtsim nature if the sprite has an associated
    /// [`ChunkResource`].
    pub fn resource_sprite(&self, pos: Vec3<i32>, sprite: SpriteKind, ori: u8) {
        self.aabb(Aabb {
            min: pos,
            max: pos + 1,
        })
        .fill(Fill::resource_sprite_ori(sprite, ori))
    }

    /// Places a sprite at the provided location with the provided orientation
    /// which will be tracked by rtsim nature if the sprite has an associated
    /// [`ChunkResource`].
    pub fn owned_resource_sprite(&self, pos: Vec3<i32>, sprite: SpriteKind, ori: u8) {
        self.aabb(Aabb {
            min: pos,
            max: pos + 1,
        })
        .fill(Fill::owned_resource_sprite_ori(sprite, ori))
    }

    /// Returns a `PrimitiveRef` of the largest pyramid with a slope of 1 that
    /// fits in the provided Aabb.
    pub fn pyramid(&self, aabb: Aabb<i32>) -> PrimitiveRef {
        let inset = 0;
        let aabb = aabb.made_valid();
        self.prim(Primitive::Ramp {
            aabb,
            inset,
            dir: Dir::X,
        })
        .intersect(self.prim(Primitive::Ramp {
            aabb,
            inset,
            dir: Dir::NegX,
        }))
        .intersect(self.prim(Primitive::Ramp {
            aabb,
            inset,
            dir: Dir::Y,
        }))
        .intersect(self.prim(Primitive::Ramp {
            aabb,
            inset,
            dir: Dir::NegY,
        }))
    }

    /// Used to create a new `PrimitiveRef`. Requires the desired `Primitive` to
    /// be supplied.
    pub fn prim(&self, prim: Primitive) -> PrimitiveRef {
        PrimitiveRef {
            id: self.prims.borrow_mut().insert(prim),
            painter: self,
        }
    }

    /// Returns a `PrimitiveRef` of an empty primitive. Useful when additional
    /// primitives are unioned within a loop.
    pub fn empty(&self) -> PrimitiveRef { self.prim(Primitive::Empty) }

    /// Fills the supplied primitive with the provided `Fill`.
    pub fn fill(&self, prim: impl Into<Id<Primitive>>, fill: Fill) {
        let prim = prim.into();
        if let Primitive::Union(a, b) = self.prims.borrow()[prim] {
            self.fill(a, fill.clone());
            self.fill(b, fill);
        } else {
            self.fills.borrow_mut().push((prim, fill));
        }
    }

    /// ```text
    ///     ___
    ///    /  /\
    ///   /__/  |
    ///  /   \  |
    /// |     | /
    /// |_____|/
    /// ```
    /// A horizontal half cylinder on top of an `Aabb`.
    pub fn vault(&self, aabb: Aabb<i32>, dir: Dir) -> PrimitiveRef {
        let h = dir.orthogonal().select(Vec3::from(aabb.size()).xy());

        let mut prim = self.horizontal_cylinder(
            Aabb {
                min: aabb.min.with_z(aabb.max.z - h),
                max: aabb.max,
            },
            dir,
        );

        if aabb.size().d < h {
            prim = prim.intersect(self.aabb(aabb));
        }

        self.aabb(Aabb {
            min: aabb.min,
            max: aabb.max.with_z(aabb.max.z - h / 2),
        })
        .union(prim)
    }

    /// Place aabbs around another aabb in a symmetric and distributed manner.
    pub fn aabbs_around_aabb(&self, aabb: Aabb<i32>, size: i32, offset: i32) -> PrimitiveRef {
        let pillar = self.aabb(Aabb {
            min: (aabb.min.xy() - 1).with_z(aabb.min.z),
            max: (aabb.min.xy() + size - 1).with_z(aabb.max.z),
        });

        let true_offset = offset + size;

        let size_x = aabb.max.x - aabb.min.x;
        let size_y = aabb.max.y - aabb.min.y;

        let num_aabbs = ((size_x + 1) / 2) / true_offset;
        let x = pillar.repeat(Vec3::new(true_offset, 0, 0), num_aabbs as u32 + 1);

        let num_aabbs = ((size_y + 1) / 2) / true_offset;
        let y = pillar.repeat(Vec3::new(0, true_offset, 0), num_aabbs as u32 + 1);
        let center = aabb.as_::<f32>().center();
        let shape = x.union(y);
        let shape =
            shape.union(shape.rotate_about(Mat3::new(-1, 0, 0, 0, -1, 0, 0, 0, -1), center));
        shape.union(shape.rotate_about(Mat3::new(0, 1, 0, -1, 0, 0, 0, 0, 1), center))
    }

    pub fn staircase_in_aabb(
        &self,
        aabb: Aabb<i32>,
        thickness: i32,
        start_dir: Dir,
    ) -> PrimitiveRef {
        let mut forward = start_dir;
        let mut z = aabb.max.z - 1;
        let aabr = Aabr::from(aabb);

        let mut prim = self.empty();

        while z > aabb.min.z {
            let right = forward.rotated_cw();
            let fc = forward.select_aabr(aabr);
            let corner =
                fc * forward.abs().to_vec2() + right.select_aabr(aabr) * right.abs().to_vec2();
            let aabb = Aabb {
                min: corner.with_z(z),
                max: (corner - (forward.to_vec2() + right.to_vec2()) * thickness).with_z(z + 1),
            }
            .made_valid();

            let stair_len = ((fc - (-forward).select_aabr(aabr)).abs() - thickness * 2).max(1) + 1;

            let stairs = self.ramp(
                Aabb {
                    min: (corner - right.to_vec2() * (stair_len + thickness)).with_z(z - stair_len),
                    max: (corner
                        - right.to_vec2() * (thickness - 1)
                        - forward.to_vec2() * thickness)
                        .with_z(z + 1),
                }
                .made_valid(),
                right,
            );

            prim = prim
                .union(self.aabb(aabb))
                .union(stairs.without(stairs.translate(Vec3::new(0, 0, -2))));

            z -= stair_len;
            forward = forward.rotated_ccw();
        }
        prim
    }

    /// A simple numeral 0-9
    pub fn numeral(&self, origin: Vec3<i32>, numeral: usize) -> PrimitiveRef {
        let bottom_bar = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y).with_z(origin.z),
            max: Vec2::new(origin.x + 1, origin.y + 4).with_z(origin.z + 1),
        });
        let mid_bar = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y).with_z(origin.z + 2),
            max: Vec2::new(origin.x + 1, origin.y + 4).with_z(origin.z + 3),
        });
        let top_bar = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y).with_z(origin.z + 4),
            max: Vec2::new(origin.x + 1, origin.y + 4).with_z(origin.z + 5),
        });
        let left_top = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y).with_z(origin.z + 2),
            max: Vec2::new(origin.x + 1, origin.y + 1).with_z(origin.z + 5),
        });
        let left_bottom = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y).with_z(origin.z),
            max: Vec2::new(origin.x + 1, origin.y + 1).with_z(origin.z + 3),
        });
        let right_top = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y + 3).with_z(origin.z + 2),
            max: Vec2::new(origin.x + 1, origin.y + 4).with_z(origin.z + 5),
        });
        let right_bottom = self.aabb(Aabb {
            min: Vec2::new(origin.x, origin.y + 3).with_z(origin.z),
            max: Vec2::new(origin.x + 1, origin.y + 4).with_z(origin.z + 3),
        });
        let number_strokes = match numeral {
            0 => &[
                top_bar,
                bottom_bar,
                right_top,
                right_bottom,
                left_top,
                left_bottom,
            ] as &[_],
            1 => &[right_top, right_bottom],
            2 => &[top_bar, right_top, mid_bar, left_bottom, bottom_bar],
            3 => &[top_bar, bottom_bar, mid_bar, right_top, right_bottom],
            4 => &[left_top, mid_bar, right_top, right_bottom],
            5 => &[top_bar, left_top, mid_bar, right_bottom, bottom_bar],
            6 => &[
                top_bar,
                left_top,
                left_bottom,
                bottom_bar,
                right_bottom,
                mid_bar,
            ],
            7 => &[top_bar, right_top, right_bottom],
            8 => &[
                top_bar,
                left_top,
                left_bottom,
                mid_bar,
                right_top,
                right_bottom,
                bottom_bar,
            ],
            _ => &[top_bar, left_top, mid_bar, right_top, right_bottom],
        };

        let mut prim = self.empty();
        for stroke in number_strokes {
            prim = prim.union(*stroke)
        }

        prim
    }

    pub fn column(&self, point: Vec2<i32>, range: impl RangeBounds<i32>) -> PrimitiveRef {
        self.aabb(Aabb {
            min: point.with_z(match range.start_bound() {
                std::ops::Bound::Included(n) => *n,
                std::ops::Bound::Excluded(n) => n + 1,
                std::ops::Bound::Unbounded => i32::MIN,
            }),
            max: (point + 1).with_z(match range.end_bound() {
                std::ops::Bound::Included(n) => n + 1,
                std::ops::Bound::Excluded(n) => *n,
                std::ops::Bound::Unbounded => i32::MAX,
            }),
        })
    }

    /// The area that the canvas is currently rendering.
    pub fn render_aabr(&self) -> Aabr<i32> { self.render_area }

    /// Spawns an entity if it is in the render_aabr, otherwise does nothing.
    pub fn spawn(&self, entity: EntityInfo) {
        if self.render_area.contains_point(entity.pos.xy().as_()) {
            self.entities.borrow_mut().push(entity)
        }
    }
}

#[derive(Copy, Clone)]
pub struct PrimitiveRef<'a> {
    id: Id<Primitive>,
    painter: &'a Painter,
}

impl<'a> From<PrimitiveRef<'a>> for Id<Primitive> {
    fn from(r: PrimitiveRef<'a>) -> Self { r.id }
}

impl<'a> PrimitiveRef<'a> {
    /// Joins two primitives together by returning the total of the blocks of
    /// both primitives. In boolean logic this is an `OR` operation.
    #[must_use]
    pub fn union(self, other: impl Into<Id<Primitive>>) -> PrimitiveRef<'a> {
        let (a, b) = self.painter.order_by_depth(self, other);
        self.painter.prim(Primitive::union(a, b))
    }

    /// Joins two primitives together by returning only overlapping blocks. In
    /// boolean logic this is an `AND` operation.
    #[must_use]
    pub fn intersect(self, other: impl Into<Id<Primitive>>) -> PrimitiveRef<'a> {
        let (a, b) = self.painter.order_by_depth(self, other);
        self.painter.prim(Primitive::intersect(a, b))
    }

    /// Subtracts the blocks of the `other` primitive from `self`. In boolean
    /// logic this is a `NOT` operation.
    #[must_use]
    pub fn without(self, other: impl Into<Id<Primitive>>) -> PrimitiveRef<'a> {
        self.painter.prim(Primitive::without(self, other))
    }

    /// Fills the primitive with `fill` and paints it into the world.
    pub fn fill(self, fill: Fill) { self.painter.fill(self, fill); }

    /// Fills the primitive with empty blocks. This will subtract any
    /// blocks in the world that inhabit the same positions as the blocks in
    /// this primitive.
    pub fn clear(self) { self.painter.fill(self, Fill::Block(Block::empty())); }

    /// Returns a `PrimitiveRef` that conforms to the provided sampling
    /// function.
    #[must_use]
    pub fn sample(self, sampling: impl Fn(Vec3<i32>) -> bool + 'static) -> PrimitiveRef<'a> {
        self.painter
            .prim(Primitive::sampling(self, Box::new(sampling)))
    }

    /// Returns a `PrimitiveRef` that conforms to the provided sampling
    /// function.
    #[must_use]
    pub fn sample_with_column(
        self,
        sampling: impl Fn(Vec3<i32>, &ColInfo) -> bool + 'static,
    ) -> PrimitiveRef<'a> {
        self.painter
            .prim(Primitive::column_sampling(self, Box::new(sampling)))
    }

    /// Rotates a primitive about it's own's bounds minimum point,
    #[must_use]
    pub fn rotate_about_min(self, mat: Mat3<i32>) -> PrimitiveRef<'a> {
        let point = Fill::get_bounds(&self.painter.prims.borrow(), self.into()).min;
        self.rotate_about(mat, point)
    }
}

/// A trait to more easily manipulate groups of primitives.
pub trait PrimitiveTransform {
    /// Translates the primitive along the vector `trans`.
    #[must_use]
    fn translate(self, trans: Vec3<i32>) -> Self;
    /// Rotates the primitive about the given point by multiplying each block
    /// position by the provided rotation matrix.
    #[must_use]
    fn rotate_about(self, rot: Mat3<i32>, point: Vec3<impl AsPrimitive<f32>>) -> Self;
    /// Rotates the primitive 90 degrees counterclockwise about the given point
    /// along the Z axis n times.
    #[must_use]
    fn rotate_z_90_about(self, n: i32, point: Vec3<impl AsPrimitive<f32>>) -> Self;
    /// Scales the primitive along each axis by the x, y, and z components of
    /// the `scale` vector respectively.
    #[must_use]
    fn scale(self, scale: Vec3<impl AsPrimitive<f32>>) -> Self;
    /// Returns a `PrimitiveRef` of the primitive in addition to the same
    /// primitive translated by `offset` and repeated `count` times, each time
    /// translated by an additional offset.
    #[must_use]
    fn repeat(self, offset: Vec3<i32>, count: u32) -> Self;
}

impl<'a> PrimitiveTransform for PrimitiveRef<'a> {
    fn translate(self, trans: Vec3<i32>) -> Self {
        self.painter.prim(Primitive::translate(self, trans))
    }

    fn rotate_about(self, rot: Mat3<i32>, point: Vec3<impl AsPrimitive<f32>>) -> Self {
        self.painter.prim(Primitive::rotate_about(self, rot, point))
    }

    fn rotate_z_90_about(self, n: i32, point: Vec3<impl AsPrimitive<f32>>) -> Self {
        self.painter
            .prim(Primitive::rotate_z_90_about(self, n, point))
    }

    fn scale(self, scale: Vec3<impl AsPrimitive<f32>>) -> Self {
        self.painter.prim(Primitive::scale(self, scale.as_()))
    }

    fn repeat(self, offset: Vec3<i32>, count: u32) -> Self {
        self.painter.prim(Primitive::repeat(self, offset, count))
    }
}

impl<'a, const N: usize> PrimitiveTransform for [PrimitiveRef<'a>; N] {
    fn translate(mut self, trans: Vec3<i32>) -> Self {
        for prim in &mut self {
            *prim = prim.translate(trans);
        }
        self
    }

    fn rotate_about(mut self, rot: Mat3<i32>, point: Vec3<impl AsPrimitive<f32>>) -> Self {
        for prim in &mut self {
            *prim = prim.rotate_about(rot, point);
        }
        self
    }

    fn rotate_z_90_about(mut self, n: i32, point: Vec3<impl AsPrimitive<f32>>) -> Self {
        for prim in &mut self {
            *prim = prim.rotate_z_90_about(n, point);
        }
        self
    }

    fn scale(mut self, scale: Vec3<impl AsPrimitive<f32>>) -> Self {
        for prim in &mut self {
            *prim = prim.scale(scale);
        }
        self
    }

    fn repeat(mut self, offset: Vec3<i32>, count: u32) -> Self {
        for prim in &mut self {
            *prim = prim.repeat(offset, count);
        }
        self
    }
}

pub trait Structure {
    #[cfg(feature = "use-dyn-lib")]
    const UPDATE_FN: &'static [u8];

    fn render_inner(&self, _site: &Site, _land: &Land, _painter: &Painter) {}

    fn render(&self, site: &Site, land: &Land, painter: &Painter) {
        #[cfg(not(feature = "use-dyn-lib"))]
        {
            self.render_inner(site, land, painter);
        }
        #[cfg(feature = "use-dyn-lib")]
        {
            let lock = LIB.lock().unwrap();
            let lib = &lock.as_ref().unwrap().lib;

            let update_fn: common_dynlib::Symbol<fn(&Self, &Site, &Land, &Painter)> = unsafe {
                //let start = std::time::Instant::now();
                // Overhead of 0.5-5 us (could use hashmap to mitigate if this is an issue)
                lib.get(Self::UPDATE_FN)
                //println!("{}", start.elapsed().as_nanos());
            }
            .unwrap_or_else(|e| {
                panic!(
                    "Trying to use: {} but had error: {:?}",
                    CStr::from_bytes_with_nul(Self::UPDATE_FN)
                        .map(CStr::to_str)
                        .unwrap()
                        .unwrap(),
                    e
                )
            });

            update_fn(self, site, land, painter);
        }
    }

    // Generate a primitive tree and fills for this structure
    fn render_collect(
        &self,
        site: &Site,
        canvas: &CanvasInfo,
    ) -> (
        Store<Primitive>,
        Vec<(Id<Primitive>, Fill)>,
        Vec<EntityInfo>,
    ) {
        let painter = Painter {
            prims: RefCell::new(Store::default()),
            fills: RefCell::new(Vec::new()),
            entities: RefCell::new(Vec::new()),
            render_area: Aabr {
                min: canvas.wpos,
                max: canvas.wpos + TerrainChunkSize::RECT_SIZE.map(|e| e as i32),
            },
        };

        self.render(site, &canvas.land(), &painter);
        (
            painter.prims.into_inner(),
            painter.fills.into_inner(),
            painter.entities.into_inner(),
        )
    }

    fn terrain_surface_at<R: Rng>(
        &self,
        _wpos: Vec2<i32>,
        _old: Block,
        _rng: &mut R,
        _col: &ColumnSample,
        _z_off: i32,
    ) -> Option<Block> {
        None
    }
}

/// Extend a 2d AABR to a 3d AABB
pub fn aabr_with_z<T>(aabr: Aabr<T>, z: Range<T>) -> Aabb<T> {
    Aabb {
        min: aabr.min.with_z(z.start),
        max: aabr.max.with_z(z.end),
    }
}

#[allow(dead_code)]
/// Just the corners of an AABB, good for outlining stuff when debugging
pub fn aabb_corners<F: FnMut(Primitive) -> Id<Primitive>>(
    prim: &mut F,
    aabb: Aabb<i32>,
) -> Id<Primitive> {
    let f = |prim: &mut F, ret, vec| {
        let sub = prim(Primitive::Aabb(Aabb {
            min: aabb.min + vec,
            max: aabb.max - vec,
        }));
        prim(Primitive::Without(ret, sub))
    };
    let mut ret = prim(Primitive::Aabb(aabb));
    ret = f(prim, ret, Vec3::new(1, 0, 0));
    ret = f(prim, ret, Vec3::new(0, 1, 0));
    ret = f(prim, ret, Vec3::new(0, 0, 1));
    ret
}

pub fn place_circular(
    center: Vec2<i32>,
    radius: f32,
    amount: i32,
) -> impl Iterator<Item = Vec2<i32>> {
    let phi = TAU / amount as f32;
    (1..=amount).map(move |n| {
        Vec2::new(
            center.x + (radius * ((n as f32 * phi).cos())) as i32,
            center.y + (radius * ((n as f32 * phi).sin())) as i32,
        )
    })
}

pub fn place_circular_as_vec(center: Vec2<i32>, radius: f32, amount: i32) -> Vec<Vec2<i32>> {
    let phi = TAU / amount as f32;
    let mut positions = vec![];
    for n in 1..=amount {
        let pos = Vec2::new(
            center.x + (radius * ((n as f32 * phi).cos())) as i32,
            center.y + (radius * ((n as f32 * phi).sin())) as i32,
        );
        positions.push(pos);
    }
    positions
}

pub fn spiral_staircase(
    origin: Vec3<i32>,
    radius: f32,
    inner_radius: f32,
    stretch: f32,
) -> Box<dyn Fn(Vec3<i32>) -> bool> {
    Box::new(move |pos: Vec3<i32>| {
        let pos = pos - origin;
        if (pos.xy().magnitude_squared() as f32) < inner_radius.powi(2) {
            true
        } else if (pos.xy().magnitude_squared() as f32) < radius.powi(2) {
            ((pos.x as f32).atan2(pos.y as f32) / (PI * 2.0) * stretch + pos.z as f32)
                .rem_euclid(stretch)
                < 1.5
        } else {
            false
        }
    })
}

pub fn wall_staircase(
    origin: Vec3<i32>,
    radius: f32,
    stretch: f32,
) -> Box<dyn Fn(Vec3<i32>) -> bool> {
    Box::new(move |pos: Vec3<i32>| {
        let pos = pos - origin;
        if (pos.x.abs().max(pos.y.abs())) as f32 > 0.6 * radius {
            ((pos.x as f32).atan2(pos.y as f32) / (PI * 2.0) * stretch + pos.z as f32)
                .rem_euclid(stretch)
                < 1.0
        } else {
            false
        }
    })
}

pub fn inscribed_polystar(
    origin: Vec2<i32>,
    radius: f32,
    sides: usize,
) -> Box<dyn Fn(Vec3<i32>) -> bool> {
    Box::new(move |pos| {
        use std::f32::consts::TAU;
        let rpos: Vec2<f32> = pos.xy().as_() - origin.as_();
        let is_border = rpos.magnitude_squared() > (radius - 2.0).powi(2);
        let is_line = (0..sides).any(|i| {
            let f = |j: f32| {
                let t = j * TAU / sides as f32;
                radius * Vec2::new(t.cos(), t.sin())
            };
            let line = LineSegment2 {
                start: f(i as f32),
                end: f((i + 2) as f32),
            };
            line.distance_to_point(rpos) <= 1.0
        });
        is_border || is_line
    })
}