1 files changed, 83 insertions, 0 deletions
diff --git a/gfx/wr/webrender/res/cs_clip_image.glsl b/gfx/wr/webrender/res/cs_clip_image.glsl
new file mode 100644
index 0000000000..248af6dbdd
--- /dev/null
+++ b/gfx/wr/webrender/res/cs_clip_image.glsl
@@ -0,0 +1,83 @@
+/* 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/. */
+
+#include shared,clip_shared
+
+varying vec4 vLocalPos;
+varying vec2 vClipMaskImageUv;
+
+flat varying vec4 vClipMaskUvRect;
+flat varying vec4 vClipMaskUvInnerRect;
+
+#ifdef WR_VERTEX_SHADER
+
+PER_INSTANCE in vec4 aClipTileRect;
+PER_INSTANCE in ivec2 aClipDataResourceAddress;
+PER_INSTANCE in vec4 aClipLocalRect;
+
+struct ClipMaskInstanceImage {
+    ClipMaskInstanceCommon shared;
+    RectWithSize tile_rect;
+    ivec2 resource_address;
+    RectWithSize local_rect;
+};
+
+ClipMaskInstanceImage fetch_clip_item() {
+    ClipMaskInstanceImage cmi;
+
+    cmi.shared = fetch_clip_item_common();
+
+    cmi.tile_rect = RectWithSize(aClipTileRect.xy, aClipTileRect.zw);
+    cmi.resource_address = aClipDataResourceAddress;
+    cmi.local_rect = RectWithSize(aClipLocalRect.xy, aClipLocalRect.zw);
+
+    return cmi;
+}
+
+void main(void) {
+    ClipMaskInstanceImage cmi = fetch_clip_item();
+    Transform clip_transform = fetch_transform(cmi.shared.clip_transform_id);
+    Transform prim_transform = fetch_transform(cmi.shared.prim_transform_id);
+    ImageResource res = fetch_image_resource_direct(cmi.resource_address);
+
+    ClipVertexInfo vi = write_clip_tile_vertex(
+        cmi.local_rect,
+        prim_transform,
+        clip_transform,
+        cmi.shared.sub_rect,
+        cmi.shared.task_origin,
+        cmi.shared.screen_origin,
+        cmi.shared.device_pixel_scale
+    );
+    vLocalPos = vi.local_pos;
+    vClipMaskImageUv = (vi.local_pos.xy - cmi.tile_rect.p0 * vi.local_pos.w) / cmi.tile_rect.size;
+
+    vec2 texture_size = vec2(textureSize(sColor0, 0));
+    vClipMaskUvRect = vec4(res.uv_rect.p0, res.uv_rect.p1 - res.uv_rect.p0) / texture_size.xyxy;
+    // applying a half-texel offset to the UV boundaries to prevent linear samples from the outside
+    vec4 inner_rect = vec4(res.uv_rect.p0, res.uv_rect.p1);
+    vClipMaskUvInnerRect = (inner_rect + vec4(0.5, 0.5, -0.5, -0.5)) / texture_size.xyxy;
+}
+#endif
+
+#ifdef WR_FRAGMENT_SHADER
+void main(void) {
+    vec2 local_pos = vLocalPos.xy / vLocalPos.w;
+    float alpha = vLocalPos.w > 0.0 ? init_transform_fs(local_pos) : 0.0;
+
+    // TODO: Handle repeating masks?
+    vec2 clamped_mask_uv = clamp(vClipMaskImageUv, vec2(0.0, 0.0), vLocalPos.ww);
+
+    // Ensure we don't draw outside of our tile.
+    // FIXME(emilio): Can we do this earlier?
+    if (clamped_mask_uv != vClipMaskImageUv)
+        discard;
+
+    vec2 source_uv = clamp(
+        clamped_mask_uv / vLocalPos.w * vClipMaskUvRect.zw + vClipMaskUvRect.xy,
+        vClipMaskUvInnerRect.xy, vClipMaskUvInnerRect.zw);
+    float clip_alpha = texture(sColor0, source_uv).r; //careful: texture has type A8
+    oFragColor = vec4(alpha * clip_alpha, 1.0, 1.0, 1.0);
+}
+#endif