Re-add culling

linebender · Nov 8, 2024 · 8323635 · 8323635
1 parent 2c89d41
commit 8323635
Showing 1 changed file with 20 additions and 17 deletions.
diff --git a/vello_shaders/shader/fine.wgsl b/vello_shaders/shader/fine.wgsl
@@ -1162,23 +1162,26 @@ fn main(
                 let image = read_image(cmd_ix);
                 let atlas_max = image.atlas_offset + image.extents - vec2(1.0);
                 for (var i = 0u; i < PIXELS_PER_THREAD; i += 1u) {
-                    let my_xy = vec2(xy.x + f32(i), xy.y);
-                    let atlas_uv = image.matrx.xy * my_xy.x + image.matrx.zw * my_xy.y + image.xlat + image.atlas_offset - vec2(0.5);
-                    // This currently only implements the Pad extend mode
-                    // TODO: Support repeat and reflect
-                    // TODO: If the image couldn't be added to the atlas (i.e. was too big), this isn't robust
-                    let atlas_uv_clamped = clamp(atlas_uv, image.atlas_offset, atlas_max);
-                    // We know that the floor and ceil are within the atlas area because atlas_max and
-                    // atlas_offset are integers
-                    let uv_quad = vec4(floor(atlas_uv_clamped), ceil(atlas_uv_clamped));
-                    let uv_frac = fract(atlas_uv);
-                    let a = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.xy), 0));
-                    let b = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.xw), 0));
-                    let c = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.zy), 0));
-                    let d = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.zw), 0));
-                    let fg_rgba = mix(mix(a, b, uv_frac.y), mix(c, d, uv_frac.y), uv_frac.x);
-                    let fg_i = fg_rgba * area[i];
-                    rgba[i] = rgba[i] * (1.0 - fg_i.a) + fg_i;
+                    // We only need to load from the textures if the value will be used.
+                    if area[i] != 0.0 {
+                        let my_xy = vec2(xy.x + f32(i), xy.y);
+                        let atlas_uv = image.matrx.xy * my_xy.x + image.matrx.zw * my_xy.y + image.xlat + image.atlas_offset - vec2(0.5);
+                        // This currently only implements the Pad extend mode
+                        // TODO: Support repeat and reflect
+                        // TODO: If the image couldn't be added to the atlas (i.e. was too big), this isn't robust
+                        let atlas_uv_clamped = clamp(atlas_uv, image.atlas_offset, atlas_max);
+                        // We know that the floor and ceil are within the atlas area because atlas_max and
+                        // atlas_offset are integers
+                        let uv_quad = vec4(floor(atlas_uv_clamped), ceil(atlas_uv_clamped));
+                        let uv_frac = fract(atlas_uv);
+                        let a = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.xy), 0));
+                        let b = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.xw), 0));
+                        let c = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.zy), 0));
+                        let d = premul_alpha(textureLoad(image_atlas, vec2<i32>(uv_quad.zw), 0));
+                        let fg_rgba = mix(mix(a, b, uv_frac.y), mix(c, d, uv_frac.y), uv_frac.x);
+                        let fg_i = fg_rgba * area[i];
+                        rgba[i] = rgba[i] * (1.0 - fg_i.a) + fg_i;
+                    }
                 }
                 cmd_ix += 2u;
             }