Added screen shaders

example/screenShader.frag

@@ -0,0 +1,16 @@
+//
+// Example blue light filter shader.
+// 
+
+precision mediump float;
+varying vec2 v_texcoord;
+uniform sampler2D tex;
+
+void main() {
+
+    vec4 pixColor = texture2D(tex, v_texcoord);
+
+    pixColor[2] *= 0.8;
+
+    gl_FragColor = pixColor;
+}