Replace MenuPaletteEffect with a post-processing shader.

glsl/postprocess_menufade.frag

@@ -0,0 +1,47 @@
+#version {VERSION}
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform float From;
+uniform float To;
+uniform float Blend;
+uniform sampler2D WorldTexture;
+
+#if __VERSION__ == 120
+uniform vec2 WorldTextureSize;
+#else
+out vec4 fragColor;
+#endif
+
+vec4 ColorForEffect(float effect, vec4 c)
+{
+	if (effect > 1.5)
+	{
+		float lum = 0.5 * (min(c.r, min(c.g, c.b)) + max(c.r, max(c.g, c.b)));
+		return vec4(lum, lum, lum, c.a);
+	}
+
+	if (effect > 0.5)
+	{
+		return vec4(0, 0, 0, c.a);
+	}
+
+	return c;
+}
+
+void main()
+{
+#if __VERSION__ == 120
+	vec4 c = texture2D(WorldTexture, gl_FragCoord.xy / WorldTextureSize);
+#else
+	vec4 c = texture(WorldTexture, gl_FragCoord.xy / textureSize(WorldTexture, 0));
+#endif
+	c = ColorForEffect(From, c) * Blend + ColorForEffect(To, c) * (1.0 - Blend);
+
+	#if __VERSION__ == 120
+	gl_FragColor = c;
+	#else
+	fragColor = c;
+	#endif
+}