gl renderer: Compute final color in vertex shader

This is a very often used shader. No need to to do this for every
fragment.

diff --git a/gsk/resources/glsl/color.glsl b/gsk/resources/glsl/color.glsl
index dcd65100a3b28aa3909865dcb47913db25fb02f4..c80f501ac02078df67e38822e8ceeeceb7331d03 100644 (file)
--- a/gsk/resources/glsl/color.glsl
+++ b/gsk/resources/glsl/color.glsl
@@ -1,16 +1,21 @@
 // VERTEX_SHADER:
+uniform vec4 u_color;
+
+_OUT_ vec4 final_color;
+
 void main() {
   gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
+
+  final_color = u_color;
+  // Pre-multiply alpha
+  final_color.rgb *= final_color.a;
+  final_color *= u_alpha;
 }
 
 // FRAGMENT_SHADER:
-uniform vec4 u_color;
+_IN_ vec4 final_color;
 
 void main() {
-  vec4 color = u_color;
-
-  // Pre-multiply alpha
-  color.rgb *= color.a;
-  setOutputColor(color * u_alpha);
+  setOutputColor(final_color);
 }
 

diff --git a/gsk/resources/glsl/preamble.vs.glsl b/gsk/resources/glsl/preamble.vs.glsl
index 6b18bb7ce2c02979c31e2a769c771ea901c7ffb5..887482fee79a416d1bcd49465a425cc8ef5f3215 100644 (file)
--- a/gsk/resources/glsl/preamble.vs.glsl
+++ b/gsk/resources/glsl/preamble.vs.glsl
@@ -1,5 +1,6 @@
 uniform mat4 u_projection;
 uniform mat4 u_modelview;
+uniform float u_alpha;
 
 #if GSK_GLES
 #define _OUT_ varying