#version 300 es
precision highp float;
uniform float iTime;
uniform vec2 iResolution;
out vec4 fragColor;
void main() {
// Screen coordinate (from [-aspect, -1] to [aspect, 1])
vec2 q = (2. * gl_FragCoord.xy - iResolution) / iResolution.y;
// Pixel color
vec3 col = .5 + .5 * sin((vec3(normalize(q), length(q)) + iTime) * 6.283);
// Output
fragColor = vec4(col, 1.);
}