Make blur work with ARGB windows

svn path=/trunk/KDE/kdebase/workspace/; revision=713247

effects/data/blur-render.frag

@@ -17,22 +17,26 @@ vec2 pix2tex(vec2 pix)
 //  account opacity, brightness and saturation
 vec4 windowColor(vec2 texcoord)
 {
-    vec3 color = texture2D(windowTex, texcoord).rgb;
+    vec4 color = texture2D(windowTex, texcoord);
     // Apply saturation
     float grayscale = dot(vec3(0.30, 0.59, 0.11), color.rgb);
-    color = mix(vec3(grayscale), color, saturation);
+    color.rgb = mix(vec3(grayscale), color.rgb, saturation);
     // Apply brightness
-    color = color * brightness;
-    // Apply opacity and return
-    return vec4(color, opacity);
+    color.rgb = color.rgb * brightness;
+    // Apply opacity
+    color.a = color.a * opacity;
+    // and return
+    return color;
 }
 
 void main()
 {
     vec2 texcoord = (gl_TexCoord[0] * gl_TextureMatrix[0]).xy;
     vec2 blurtexcoord = pix2tex(gl_FragCoord.xy); //(gl_FragCoord * gl_TextureMatrix[4]).xy;
+
+    vec4 winColor = windowColor(texcoord);
     vec3 tex = mix(texture2D(backgroundTex, blurtexcoord).rgb,
-                   windowColor(texcoord).rgb, opacity);
+                   winColor.rgb, winColor.a * opacity);
 
     gl_FragColor = vec4(tex, 1.0);
 }