#version 300 es precision mediump float; uniform vec2 resolution; uniform float time; out vec4 fragmentColor; void main() { vec2 uv = (gl_FragCoord.xy * 2. - resolution) / resolution.y; float red = uv.x + 0.5; float green = -max(uv.x, -0.25) - min(uv.y, 0.25); float blue = uv.y + 0.5; fragmentColor = vec4(red, green, blue, 1); }