Constant DEFAULT_SHADER

pub const DEFAULT_SHADER: &str = r#"// custom effect — edit freely
vec4 effect(vec4 src, vec2 uv) {
    // u1 = amount, u2 = speed
    float wave = sin(uv.y * 40.0 + u_time * max(u2, 0.0) * 6.28318) * u1 * 0.02;
    return texture(tex, vec2(uv.x + wave, uv.y));
}
"#;

Starting point for EffectKind::Shader: tex = the layer, uv = 0..1, u_time = clip-local seconds, u1..u8 = the eight knobs, u_res = layer size in px. Output goes to out_color (straight alpha, same convention as every other effect).