1 files changed, 113 insertions, 0 deletions
diff --git a/gfx/wr/webrender/res/brush_opacity.glsl b/gfx/wr/webrender/res/brush_opacity.glsl
new file mode 100644
index 0000000000..25fe1cb5aa
--- /dev/null
+++ b/gfx/wr/webrender/res/brush_opacity.glsl
@@ -0,0 +1,113 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#define VECS_PER_SPECIFIC_BRUSH 3
+#define WR_FEATURE_TEXTURE_2D
+
+#include shared,prim_shared,brush
+
+// Interpolated UV coordinates to sample.
+varying vec2 v_uv;
+varying vec2 v_local_pos;
+
+// Normalized bounds of the source image in the texture, adjusted to avoid
+// sampling artifacts.
+flat varying vec4 v_uv_sample_bounds;
+
+// Layer index to sample.
+// Flag to allow perspective interpolation of UV.
+flat varying float v_perspective;
+
+flat varying float v_opacity;
+
+#ifdef WR_VERTEX_SHADER
+void brush_vs(
+    VertexInfo vi,
+    int prim_address,
+    RectWithSize local_rect,
+    RectWithSize segment_rect,
+    ivec4 prim_user_data,
+    int specific_resource_address,
+    mat4 transform,
+    PictureTask pic_task,
+    int brush_flags,
+    vec4 unused
+) {
+    ImageResource res = fetch_image_resource(prim_user_data.x);
+    vec2 uv0 = res.uv_rect.p0;
+    vec2 uv1 = res.uv_rect.p1;
+
+    vec2 texture_size = vec2(textureSize(sColor0, 0).xy);
+    vec2 f = (vi.local_pos - local_rect.p0) / local_rect.size;
+    f = get_image_quad_uv(prim_user_data.x, f);
+    vec2 uv = mix(uv0, uv1, f);
+    float perspective_interpolate = (brush_flags & BRUSH_FLAG_PERSPECTIVE_INTERPOLATION) != 0 ? 1.0 : 0.0;
+
+    v_uv = uv / texture_size * mix(vi.world_pos.w, 1.0, perspective_interpolate);
+    v_perspective = perspective_interpolate;
+
+    v_uv_sample_bounds = vec4(uv0 + vec2(0.5), uv1 - vec2(0.5)) / texture_size.xyxy;
+
+    #ifdef WR_FEATURE_ANTIALIASING
+        v_local_pos = vi.local_pos;
+    #endif
+
+    v_opacity = float(prim_user_data.y) / 65536.0;
+}
+#endif
+
+#ifdef WR_FRAGMENT_SHADER
+Fragment brush_fs() {
+    float perspective_divisor = mix(gl_FragCoord.w, 1.0, v_perspective);
+    vec2 uv = v_uv * perspective_divisor;
+    // Clamp the uvs to avoid sampling artifacts.
+    uv = clamp(uv, v_uv_sample_bounds.xy, v_uv_sample_bounds.zw);
+
+    // No need to un-premultiply since we'll only apply a factor to the alpha.
+    vec4 color = texture(sColor0, uv);
+
+    float alpha = v_opacity;
+
+    #ifdef WR_FEATURE_ANTIALIASING
+        alpha *= init_transform_fs(v_local_pos);
+    #endif
+
+    // Pre-multiply the contribution of the opacity factor.
+    return Fragment(alpha * color);
+}
+
+#if defined(SWGL) && !defined(WR_FEATURE_DUAL_SOURCE_BLENDING)
+void swgl_drawSpanRGBA8() {
+    if (!swgl_isTextureRGBA8(sColor0)) {
+        return;
+    }
+
+    float perspective_divisor = mix(swgl_forceScalar(gl_FragCoord.w), 1.0, v_perspective);
+    vec2 uv = v_uv * perspective_divisor;
+
+    #ifndef WR_FEATURE_ANTIALIASING
+    if (swgl_allowTextureNearest(sColor0, uv)) {
+        swgl_commitTextureNearestColorRGBA8(sColor0, uv, v_uv_sample_bounds, v_opacity, 0);
+        return;
+    }
+    #endif
+
+    uv = swgl_linearQuantize(sColor0, uv);
+    vec2 min_uv = swgl_linearQuantize(sColor0, v_uv_sample_bounds.xy);
+    vec2 max_uv = swgl_linearQuantize(sColor0, v_uv_sample_bounds.zw);
+    vec2 step_uv = swgl_linearQuantizeStep(sColor0, swgl_interpStep(v_uv)) * perspective_divisor;
+
+    while (swgl_SpanLength > 0) {
+        float alpha = v_opacity;
+        #ifdef WR_FEATURE_ANTIALIASING
+            alpha *= init_transform_fs(v_local_pos);
+            v_local_pos += swgl_interpStep(v_local_pos);
+        #endif
+        swgl_commitTextureLinearColorRGBA8(sColor0, clamp(uv, min_uv, max_uv), alpha, 0);
+        uv += step_uv;
+    }
+}
+#endif
+
+#endif