#include "common_uniforms"
#include "math/common_utils"
#include "render/fullscreen_uv_vs"  // <- VertexOutput + vs_main

@group(0) @binding(0) var sky_tex: texture_2d<f32>;
@group(0) @binding(1) var sky_sampler: sampler;
@group(0) @binding(2) var<uniform> globals: GlobalUniforms;

@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4f {
    // Convert UV to NDC
    let ndc_x = in.uv.x * 2.0 - 1.0;
    let ndc_y = (1.0 - in.uv.y) * 2.0 - 1.0; // Un-flip Y for NDC (Y-up)
    
    // Unproject to find world direction
    // We want the direction from camera to the far plane at this pixel
    let clip_pos = vec4f(ndc_x, ndc_y, 1.0, 1.0);
    let world_pos_h = globals.inv_view_proj * clip_pos;
    let world_pos = world_pos_h.xyz / world_pos_h.w;
    
    let ray_dir = normalize(world_pos - globals.camera_pos_time.xyz);
    let uv = spherical_uv_from_dir(ray_dir);
    return textureSample(sky_tex, sky_sampler, uv);
}