Allow large numbers of draw objects

crates/encoding/src/config.rs

@@ -234,6 +234,7 @@ impl WorkgroupCounts {
             path_tag_wgs
         };
         let draw_object_wgs = (n_draw_objects + PATH_BBOX_WG - 1) / PATH_BBOX_WG;
+        let draw_monoid_wgs = draw_object_wgs.min(PATH_BBOX_WG);
         let flatten_wgs = (n_path_tags + FLATTEN_WG - 1) / FLATTEN_WG;
         let clip_reduce_wgs = n_clips.saturating_sub(1) / CLIP_REDUCE_WG;
         let clip_wgs = (n_clips + CLIP_REDUCE_WG - 1) / CLIP_REDUCE_WG;
@@ -248,8 +249,8 @@ impl WorkgroupCounts {
             path_scan: (path_tag_wgs, 1, 1),
             bbox_clear: (draw_object_wgs, 1, 1),
             flatten: (flatten_wgs, 1, 1),
-            draw_reduce: (draw_object_wgs, 1, 1),
-            draw_leaf: (draw_object_wgs, 1, 1),
+            draw_reduce: (draw_monoid_wgs, 1, 1),
+            draw_leaf: (draw_monoid_wgs, 1, 1),
             clip_reduce: (clip_reduce_wgs, 1, 1),
             clip_leaf: (clip_wgs, 1, 1),
             binning: (draw_object_wgs, 1, 1),
@@ -364,8 +365,9 @@ impl BufferSizes {
         let path_reduced_scan = BufferSize::new(path_tag_wgs);
         let path_monoids = BufferSize::new(path_tag_wgs * PATH_REDUCE_WG);
         let path_bboxes = BufferSize::new(n_paths);
-        let draw_object_wgs = workgroups.draw_reduce.0;
-        let draw_reduced = BufferSize::new(draw_object_wgs);
+        let binning_wgs = workgroups.binning.0;
+        let draw_monoid_wgs = workgroups.draw_reduce.0;
+        let draw_reduced = BufferSize::new(draw_monoid_wgs);
         let draw_monoids = BufferSize::new(n_draw_objects);
         let info = BufferSize::new(layout.bin_data_start);
         let clip_inps = BufferSize::new(n_clips);
@@ -375,7 +377,7 @@ impl BufferSizes {
         let draw_bboxes = BufferSize::new(n_paths);
         let bump_alloc = BufferSize::new(1);
         let indirect_count = BufferSize::new(1);
-        let bin_headers = BufferSize::new(draw_object_wgs * 256);
+        let bin_headers = BufferSize::new(binning_wgs * 256);
         let n_paths_aligned = align_up(n_paths, 256);
         let paths = BufferSize::new(n_paths_aligned);
 

examples/scenes/src/test_scenes.rs

@@ -2,7 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
 use crate::{ExampleScene, SceneConfig, SceneParams, SceneSet};
-use vello::kurbo::{Affine, BezPath, Cap, Ellipse, Join, PathEl, Point, Rect, Shape, Stroke, Vec2};
+use vello::kurbo::{
+    Affine, BezPath, Cap, Circle, Ellipse, Join, PathEl, Point, Rect, Shape, Stroke, Vec2,
+};
 use vello::peniko::*;
 use vello::*;
 
@@ -60,6 +62,7 @@ pub fn test_scenes() -> SceneSet {
         scene!(longpathdash(Cap::Butt), "longpathdash (butt caps)", false),
         scene!(longpathdash(Cap::Round), "longpathdash (round caps)", false),
         scene!(crate::mmark::MMark::new(80_000), "mmark", false),
+        scene!(many_draw_objects),
     ];
 
     SceneSet { scenes }
@@ -1520,6 +1523,22 @@ fn make_diamond(cx: f64, cy: f64) -> [PathEl; 5] {
     ]
 }
 
+fn many_draw_objects(scene: &mut Scene, params: &mut SceneParams) {
+    const N_WIDE: usize = 300;
+    const N_HIGH: usize = 300;
+    const SCENE_WIDTH: f64 = 2000.0;
+    const SCENE_HEIGHT: f64 = 1500.0;
+    params.resolution = Some((SCENE_WIDTH, SCENE_HEIGHT).into());
+    for j in 0..N_HIGH {
+        let y = (j as f64 + 0.5) * (SCENE_HEIGHT / N_HIGH as f64);
+        for i in 0..N_WIDE {
+            let x = (i as f64 + 0.5) * (SCENE_WIDTH / N_WIDE as f64);
+            let c = Circle::new((x, y), 3.0);
+            scene.fill(Fill::NonZero, Affine::IDENTITY, Color::YELLOW, None, &c);
+        }
+    }
+}
+
 fn splash_screen(scene: &mut Scene, params: &mut SceneParams) {
     let strings = [
         "Vello test",

shader/coarse.wgsl

@@ -236,6 +236,7 @@ fn main(
             if wr_ix - rd_ix >= N_TILE || (wr_ix >= ready_ix && partition_ix >= n_partitions) {
                 break;
             }
+            workgroupBarrier();
         }
         // At this point, sh_drawobj_ix[0.. wr_ix - rd_ix] contains merged binning results.
         var tag = DRAWTAG_NOP;