#version 330

in vec3 localPos;
out vec4 fragColor;

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;
	return uv + 0.5;
}

void main() {
	vec2 uv = sampleSphericalMap(normalize(localPos));
	fragColor = vec4(texture(equirectangularMap, uv).rgb, 1.f);
}