inverting-game/fragment.fs

#version 430

uniform mat4 projMatrix;
uniform mat4 viewMatrix;

in vec4 outColor;
in vec2 outTex;
out vec4 color;

void main(void)
{
    //color = outColor * (length(outTex - vec2(0.5, 0.5)) + 0.5);
    color = outColor * (max(abs(outTex.y - 0.5), abs(outTex.x - 0.5)) + 0.2);
}