GLSL_light_sample.frag

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // Time varying pixel color
    vec3 lightColor = vec3(
        clamp(mod(float(iFrame + 50), 100.0) / 100.0, 0.0, 1.0),
        clamp(mod(float(iFrame + 100), 100.0) / 100.0, 0.0, 1.0),
        clamp(mod(float(iFrame), 100.0) / 100.0, 0.0, 1.0)
    );
    vec3 pixelColor = vec3(0.0, 1.0, 1.0);
    vec2 toLight = vec2(iMouse.x - fragCoord.x, iMouse.y - fragCoord.y);
    
    float lightradius = 150.0;
    float brightness = 1.0;
    
    // Apply distance to brightness
    brightness *= clamp(1.0 - (length(toLight) / lightradius), 0.0, 1.0);

    vec3 finalcolor = pixelColor.rgb * lightColor * brightness;

    // Output to screen
    fragColor = vec4(finalcolor, 1.0);
}