OF_GLSL_SHADER_HEADER
precision mediump float;

uniform sampler2DRect tex0;
in vec2 varyingtexcoord;
out vec4 fragColor;



void main() {
    vec4 texColor = texture(tex0, varyingtexcoord);
    float gray = dot(texColor.rgb, vec3(0.299, 0.587, 0.114)); // Standard luminance formula
    fragColor = vec4(vec3(gray), 1.0);
}