Optimizations and more documentation of SkShadowShader
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2285133002
Review-Url: https://codereview.chromium.org/2285133002
diff --git a/src/core/SkShadowShader.h b/src/core/SkShadowShader.h
index 3263950..ea05cca 100644
--- a/src/core/SkShadowShader.h
+++ b/src/core/SkShadowShader.h
@@ -19,6 +19,9 @@
/** This shader combines the diffuse color in 'diffuseShader' with the shadows
* determined by the 'povDepthShader' and the shadow maps stored in each of the
* lights in 'lights'
+ *
+ * Please note that the shadow shader is required to be in Stage0, otherwise
+ * the texture coords will be wrong within the shader.
*/
static sk_sp<SkShader> Make(sk_sp<SkShader> povDepthShader,
sk_sp<SkShader> diffuseShader,