embedded_3dgfx/
tilebin.rs

1use crate::DrawPrimitive;
2use crate::command_buffer::{CommandBuffer, RenderCommand};
3use crate::error::RenderError;
4
5#[derive(Debug, Clone, Copy, PartialEq, Eq)]
6pub struct TileConfig {
7    pub tile_width: usize,
8    pub tile_height: usize,
9}
10
11#[derive(Debug, Clone, Copy, PartialEq, Eq)]
12pub struct TileGrid {
13    pub cols: usize,
14    pub rows: usize,
15}
16
17#[derive(Debug, Clone, Copy, PartialEq, Eq)]
18pub struct TileBinStats {
19    pub draw_commands: usize,
20    pub bins_used: usize,
21}
22
23fn primitive_bounds(primitive: &DrawPrimitive) -> (i32, i32, i32, i32) {
24    match primitive {
25        DrawPrimitive::ColoredPoint(p, _) => (p.x, p.y, p.x, p.y),
26        DrawPrimitive::Line([a, b], _) => (a.x.min(b.x), a.y.min(b.y), a.x.max(b.x), a.y.max(b.y)),
27        DrawPrimitive::ColoredTriangle(points, _)
28        | DrawPrimitive::ColoredTriangleWithDepth { points, .. }
29        | DrawPrimitive::GouraudTriangle { points, .. }
30        | DrawPrimitive::GouraudTriangleWithDepth { points, .. }
31        | DrawPrimitive::TexturedTriangle { points, .. }
32        | DrawPrimitive::TexturedTriangleWithDepth { points, .. } => {
33            let min_x = points.iter().map(|p| p.x).min().unwrap_or(0);
34            let min_y = points.iter().map(|p| p.y).min().unwrap_or(0);
35            let max_x = points.iter().map(|p| p.x).max().unwrap_or(0);
36            let max_y = points.iter().map(|p| p.y).max().unwrap_or(0);
37            (min_x, min_y, max_x, max_y)
38        }
39    }
40}
41
42pub fn tile_grid(width: usize, height: usize, config: TileConfig) -> Result<TileGrid, RenderError> {
43    if config.tile_width == 0 || config.tile_height == 0 {
44        return Err(RenderError::InvalidInput("tile dimensions must be >= 1"));
45    }
46    let cols = width.div_ceil(config.tile_width);
47    let rows = height.div_ceil(config.tile_height);
48    Ok(TileGrid { cols, rows })
49}
50
51pub fn build_bins<const MAX: usize, const BIN_CAP: usize>(
52    commands: &CommandBuffer<MAX>,
53    width: usize,
54    height: usize,
55    config: TileConfig,
56) -> Result<
57    (
58        heapless::Vec<heapless::Vec<usize, BIN_CAP>, BIN_CAP>,
59        TileBinStats,
60    ),
61    RenderError,
62> {
63    let grid = tile_grid(width, height, config)?;
64    let bin_count = grid.cols * grid.rows;
65    if bin_count > BIN_CAP {
66        return Err(RenderError::InvalidInput("tile bin count exceeds BIN_CAP"));
67    }
68
69    let mut bins: heapless::Vec<heapless::Vec<usize, BIN_CAP>, BIN_CAP> = heapless::Vec::new();
70    for _ in 0..bin_count {
71        bins.push(heapless::Vec::new())
72            .map_err(|_| RenderError::InvalidInput("unable to allocate tile bins"))?;
73    }
74
75    let mut draw_commands = 0usize;
76    for (idx, command) in commands.iter().enumerate() {
77        let RenderCommand::Draw(primitive) = command else {
78            continue;
79        };
80        draw_commands += 1;
81        let (min_x, min_y, max_x, max_y) = primitive_bounds(primitive);
82        let clamp =
83            |v: i32, max_v: usize| -> usize { v.clamp(0, max_v.saturating_sub(1) as i32) as usize };
84        let x0 = clamp(min_x, width) / config.tile_width;
85        let y0 = clamp(min_y, height) / config.tile_height;
86        let x1 = clamp(max_x, width) / config.tile_width;
87        let y1 = clamp(max_y, height) / config.tile_height;
88        for ty in y0..=y1 {
89            for tx in x0..=x1 {
90                let bin_index = ty * grid.cols + tx;
91                bins[bin_index].push(idx).map_err(|_| {
92                    RenderError::OutOfBudget(crate::error::BudgetKind::DrawPrimitives {
93                        attempted: idx + 1,
94                        max: BIN_CAP,
95                    })
96                })?;
97            }
98        }
99    }
100
101    let bins_used = bins.iter().filter(|bin| !bin.is_empty()).count();
102    Ok((
103        bins,
104        TileBinStats {
105            draw_commands,
106            bins_used,
107        },
108    ))
109}
embedded_3dgfx/tilebin.rs

embedded_3dgfx/
tilebin.rs
