PostProcessing: Add support for user-supplied anaglyph shaders.

There are lots of different anaglyph glasses out there and there may be even more creative uses for stereoscopic post-processing shaders.

Data/Sys/Shaders/Anaglyph/dubois.glsl

@@ -0,0 +1,18 @@
+// Anaglyph Red-Cyan shader based on Dubois algorithm
+// Constants taken from the paper:
+// "Conversion of a Stereo Pair to Anaglyph with
+// the Least-Squares Projection Method"
+// Eric Dubois, March 2009
+
+void main()
+{
+	float4 c0 = SampleLayer(0);
+	float4 c1 = SampleLayer(1);
+	mat3 l = mat3( 0.437, 0.449, 0.164,
+	              -0.062,-0.062,-0.024,
+	              -0.048,-0.050,-0.017);
+	mat3 r = mat3(-0.011,-0.032,-0.007,
+	               0.377, 0.761, 0.009,
+	              -0.026,-0.093, 1.234);
+	SetOutput(float4(c0.rgb * l + c1.rgb * r, c0.a));
+}