#import bevy_sprite::mesh2d_vertex_output::VertexOutput

@group(2) @binding(0) var<uniform> u_time: f32;
@group(2) @binding(1) var<uniform> u_resolution: vec2<f32>;

@fragment
fn fragment(mesh: VertexOutput) -> @location(0) vec4<f32> {
    // very simple vertical gradient between two colors
    let bottom = vec3<f32>(1.0, 0.8, 0.2); // warm
    let top    = vec3<f32>(0.2, 0.6, 1.0); // cool

    // use time to subtly shift the gradient
    let t = u_time;
    let shift = 0.2 * sin(t);

    let color = mix(bottom, top, mesh.uv.y + shift);
    return vec4<f32>(color, 1.0);
}