experimental map shaders

modules/game_shaders/shaders/sepia.frag

@@ -0,0 +1,16 @@
+uniform float u_Time;
+uniform sampler2D u_Tex0;
+varying vec2 v_TexCoord;
+
+vec4 sepia(vec4 color)
+{
+    return vec4(dot(color, vec4(.393, .769, .189, .0)),
+                dot(color, vec4(.349, .686, .168, .0)),
+                dot(color, vec4(.272, .534, .131, .0)),
+                1);
+}
+
+void main()
+{
+    gl_FragColor = sepia(texture2D(u_Tex0, v_TexCoord));
+}