dotfiles

 1// Monochrome filter
 2
 3#version 300 es
 4precision mediump float;
 5
 6in vec2 v_texcoord;
 7uniform sampler2D tex;
 8
 9out vec4 fragColor;
10
11void main()
12{
13   vec4 pixColor = texture(tex, v_texcoord);
14
15   // Check https://en.wikipedia.org/wiki/Grayscale#Luma_coding_in_video_systems for which one to choose
16   float lum = dot(pixColor.rgb, vec3(0.299, 0.587, 0.114)); // BT.601
17   // float lum = dot(pixColor.rgb, vec3(0.2126, 0.7152, 0.0722)); // BT.709
18   // float lum = dot(pixColor.rgb, vec3(0.2627, 0.6780, 0.0593)); // BT.2100
19
20   fragColor = vec4(vec3(lum), pixColor.a);
21}