-uniform sampler2D input_tex;
-varying vec2 tc;
-
-vec4 read_input(vec2 tc)
-{
- return texture2D(input_tex, tc.st);
-}
+#ifdef GL_EXT_gpu_shader4
+// We sometimes want round().
+#extension GL_EXT_gpu_shader4 : enable
+#endif
-#define INPUT read_input
+varying vec2 tc;