83 lines
2.9 KiB
Rust
83 lines
2.9 KiB
Rust
// pathfinder/renderer/src/z_buffer.rs
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//
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// Copyright © 2019 The Pathfinder Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Software occlusion culling.
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use crate::gpu_data::{BuiltObject, SolidTileScenePrimitive};
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use crate::scene;
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use crate::tiles;
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use euclid::Rect;
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use std::sync::atomic::{AtomicUsize, Ordering as AtomicOrdering};
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pub struct ZBuffer {
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buffer: Vec<AtomicUsize>,
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tile_rect: Rect<i16>,
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}
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impl ZBuffer {
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pub fn new(view_box: &Rect<f32>) -> ZBuffer {
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let tile_rect = tiles::round_rect_out_to_tile_bounds(view_box);
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let tile_area = tile_rect.size.width as usize * tile_rect.size.height as usize;
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ZBuffer {
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buffer: (0..tile_area).map(|_| AtomicUsize::new(0)).collect(),
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tile_rect,
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}
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}
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pub fn test(&self, scene_tile_index: u32, object_index: u32) -> bool {
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let existing_depth = self.buffer[scene_tile_index as usize].load(AtomicOrdering::SeqCst);
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existing_depth < object_index as usize + 1
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}
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pub fn update(&self, tile_x: i16, tile_y: i16, object_index: u16) {
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let scene_tile_index = scene::scene_tile_index(tile_x, tile_y, self.tile_rect) as usize;
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let mut old_depth = self.buffer[scene_tile_index].load(AtomicOrdering::SeqCst);
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let new_depth = (object_index + 1) as usize;
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while old_depth < new_depth {
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let prev_depth = self.buffer[scene_tile_index].compare_and_swap(
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old_depth,
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new_depth,
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AtomicOrdering::SeqCst,
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);
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if prev_depth == old_depth {
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// Successfully written.
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return;
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}
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old_depth = prev_depth;
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}
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}
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pub fn build_solid_tiles(
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&self,
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objects: &[BuiltObject],
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tile_rect: &Rect<i16>,
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) -> Vec<SolidTileScenePrimitive> {
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let mut solid_tiles = vec![];
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for scene_tile_y in 0..tile_rect.size.height {
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for scene_tile_x in 0..tile_rect.size.width {
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let scene_tile_index =
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scene_tile_y as usize * tile_rect.size.width as usize + scene_tile_x as usize;
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let depth = self.buffer[scene_tile_index].load(AtomicOrdering::Relaxed);
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if depth == 0 {
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continue;
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}
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let object_index = (depth - 1) as usize;
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solid_tiles.push(SolidTileScenePrimitive {
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tile_x: scene_tile_x + tile_rect.origin.x,
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tile_y: scene_tile_y + tile_rect.origin.y,
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shader: objects[object_index].shader,
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});
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}
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}
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solid_tiles
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}
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}
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