// Example Shadertoy-style fragment shader for gpupaper.
// Demonstrates use of 'time' and 'resolution' uniforms.
//
// Usage: gpupaper HDMI-A-1 shaders/example.frag

uniform vec2 resolution;
uniform float time;

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = fragCoord / resolution;

    // Animated gradient
    float r = 0.5 + 0.5 * sin(time * 0.7 + uv.x * 3.0);
    float g = 0.5 + 0.5 * sin(time * 0.5 + uv.y * 3.0 + 2.094);
    float b = 0.5 + 0.5 * sin(time * 0.3 + (uv.x + uv.y) * 3.0 + 4.189);

    // Vignette
    vec2 centered = uv - 0.5;
    float vignette = 1.0 - dot(centered, centered) * 2.0;
    vignette = clamp(vignette, 0.0, 1.0);

    fragColor = vec4(vec3(r, g, b) * vignette, 1.0);
}