void main()
{
    vec2 uv = (gl_FragCoord.xy / u_resolution) * 2.0 - 1.0;
    float aspect = u_resolution.x / u_resolution.y;
    uv.x *= aspect;

    mat3 view3 = mat3(u_view);
    vec3 forward = -vec3(u_view[0][2], u_view[1][2], u_view[2][2]);
    vec3 right   =  vec3(u_view[0][0], u_view[1][0], u_view[2][0]);
    vec3 up      =  vec3(u_view[0][1], u_view[1][1], u_view[2][1]);

    float fovy   = 2.0 * atan(1.0 / u_proj[1][1]);
    float fovScale = tan(fovy * 0.5);

    vec3 n = normalize(forward + right * uv.x * fovScale + up * uv.y * fovScale);

    vec3 sky = textureLod(t_sky, n, u_roughness * 8.0).rgb * u_strength; 
    out_color0 = vec4(sky, 1.0);
}