#version 460 core
out vec4 FragColor;
in vec3 localPos;

uniform sampler2D equirectangularMap;

const vec2 invAtan = vec2(0.1591, 0.3183);

vec2 SampleSphericalMap(vec3 v)
{
    vec2 uv = vec2(atan(v.z, v.x), asin(v.y));
    uv *= invAtan;
    uv += 0.5;
    return uv;
}

void main(){
    vec2 uv = SampleSphericalMap(localPos);
    vec3 color = texture(equirectangularMap, uv).rgb;

    FragColor = vec4(color,1.0);
}