pxl8/pxl8d/src/bsp.rs

extern crate alloc;

use alloc::vec::Vec;

use crate::math::Vec3;

#[derive(Clone, Copy, Default)]
pub struct BspVertex {
    pub position: Vec3,
}

#[derive(Clone, Copy, Default)]
pub struct BspEdge {
    pub vertex: [u16; 2],
}

#[derive(Clone, Copy, Default)]
pub struct BspFace {
    pub first_edge: u32,
    pub lightmap_offset: u32,
    pub num_edges: u16,
    pub plane_id: u16,
    pub side: u16,
    pub styles: [u8; 4],
    pub material_id: u16,
    pub aabb_min: Vec3,
    pub aabb_max: Vec3,
}

#[derive(Clone, Copy, Default)]
pub struct BspPlane {
    pub normal: Vec3,
    pub dist: f32,
    pub plane_type: i32,
}

#[derive(Clone, Copy, Default)]
pub struct BspNode {
    pub children: [i32; 2],
    pub first_face: u16,
    pub maxs: [i16; 3],
    pub mins: [i16; 3],
    pub num_faces: u16,
    pub plane_id: u32,
}

#[derive(Clone, Copy, Default)]
pub struct BspLeaf {
    pub ambient_level: [u8; 4],
    pub contents: i32,
    pub first_marksurface: u16,
    pub maxs: [i16; 3],
    pub mins: [i16; 3],
    pub num_marksurfaces: u16,
    pub visofs: i32,
}

#[derive(Clone, Copy, Default)]
pub struct BspPortal {
    pub x0: f32,
    pub z0: f32,
    pub x1: f32,
    pub z1: f32,
    pub target_leaf: u32,
}

#[derive(Clone, Default)]
pub struct BspCellPortals {
    pub portals: [BspPortal; 4],
    pub num_portals: u8,
}

pub struct Bsp {
    pub vertices: Vec<BspVertex>,
    pub edges: Vec<BspEdge>,
    pub surfedges: Vec<i32>,
    pub planes: Vec<BspPlane>,
    pub faces: Vec<BspFace>,
    pub nodes: Vec<BspNode>,
    pub leafs: Vec<BspLeaf>,
    pub marksurfaces: Vec<u16>,
    pub cell_portals: Vec<BspCellPortals>,
    pub visdata: Vec<u8>,
    pub vertex_lights: Vec<u32>,
}

impl Bsp {
    pub fn new() -> Self {
        Self {
            vertices: Vec::new(),
            edges: Vec::new(),
            surfedges: Vec::new(),
            planes: Vec::new(),
            faces: Vec::new(),
            nodes: Vec::new(),
            leafs: Vec::new(),
            marksurfaces: Vec::new(),
            cell_portals: Vec::new(),
            visdata: Vec::new(),
            vertex_lights: Vec::new(),
        }
    }

    pub fn find_leaf(&self, pos: Vec3) -> i32 {
        if self.nodes.is_empty() {
            return -1;
        }

        let mut node_id: i32 = 0;

        while node_id >= 0 {
            let node = &self.nodes[node_id as usize];
            let plane = &self.planes[node.plane_id as usize];

            let dist = pos.dot(plane.normal) - plane.dist;
            node_id = node.children[if dist < 0.0 { 1 } else { 0 }];
        }

        -(node_id + 1)
    }

    pub fn point_solid(&self, pos: Vec3) -> bool {
        let leaf = self.find_leaf(pos);
        if leaf < 0 || leaf as usize >= self.leafs.len() {
            return true;
        }
        self.leafs[leaf as usize].contents == -1
    }

    fn point_clear(&self, x: f32, y: f32, z: f32, radius: f32) -> bool {
        if self.point_solid(Vec3::new(x, y, z)) { return false; }
        if self.point_solid(Vec3::new(x + radius, y, z)) { return false; }
        if self.point_solid(Vec3::new(x - radius, y, z)) { return false; }
        if self.point_solid(Vec3::new(x, y, z + radius)) { return false; }
        if self.point_solid(Vec3::new(x, y, z - radius)) { return false; }
        true
    }

    pub fn trace(&self, from: Vec3, to: Vec3, radius: f32) -> Vec3 {
        if self.nodes.is_empty() {
            return to;
        }

        if self.point_clear(to.x, to.y, to.z, radius) {
            return to;
        }

        let x_ok = self.point_clear(to.x, from.y, from.z, radius);
        let z_ok = self.point_clear(from.x, from.y, to.z, radius);

        if x_ok && z_ok {
            let dx = to.x - from.x;
            let dz = to.z - from.z;
            if dx * dx > dz * dz {
                Vec3::new(to.x, from.y, from.z)
            } else {
                Vec3::new(from.x, from.y, to.z)
            }
        } else if x_ok {
            Vec3::new(to.x, from.y, from.z)
        } else if z_ok {
            Vec3::new(from.x, from.y, to.z)
        } else {
            from
        }
    }
}

impl Default for Bsp {
    fn default() -> Self {
        Self::new()
    }
}