#version 450
layout(location = 0) out vec4 FragColor;
layout(location = 0) in vec4 v0;
void main()
{
FragColor = vec4(1.0);
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
FragColor += vec4(v0[(i + j) & 3]);
}