5 out float element_sum_idx;
7 uniform vec2 image_size;
11 // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is:
13 // 2.000 0.000 0.000 -1.000
14 // 0.000 2.000 0.000 -1.000
15 // 0.000 0.000 -2.000 -1.000
16 // 0.000 0.000 0.000 1.000
17 gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0);
20 vec2 element_idx = position * image_size - 0.5;
21 element_sum_idx = element_idx.x + element_idx.y;