#version 330 core

#define AIR_IOR 1.0
#define GLASS_IOR 1.52

in vec3 vert_normal;
in vec3 frag_position;

uniform vec3 camera_position;
uniform samplerCube cubemap;

out vec4 color;

void main() {
  vec3 view_direction    = normalize(frag_position - camera_position);
  vec3 refract_direction = refract(view_direction, normalize(vert_normal), AIR_IOR / GLASS_IOR);

  color = vec4(texture(cubemap, refract_direction).rgb, 1.0);
}