#version 430 layout(location = 0) uniform sampler2D RT; layout(location = 0) in vec2 oUv0; layout(location = 0) out vec4 fragColor; void main() { vec3 greyscale = vec3(dot(texture(RT, oUv0).rgb, vec3(0.3, 0.59, 0.11))); fragColor = vec4(greyscale, 1.0); }