Add reflective and refractive models

shaders/frag.glsl

@@ -53,7 +53,7 @@ vec3 calc_spot_light(SpotLight light, vec3 normal, vec3 frag_position, vec3 view
 
 void main() {
   vec3  normal         = normalize(vert_normal);
-  vec3  view_direction = normalize(camera_position - frag_position);
+  vec3  view_direction = normalize(frag_position - camera_position);
 
   vec3 result = calc_dir_light(directional_light, normal, view_direction);
 

shaders/reflective_frag.glsl

@@ -0,0 +1,16 @@
+#version 330 core
+
+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 reflect_direction = reflect(view_direction, normalize(vert_normal));
+
+  color = vec4(texture(cubemap, reflect_direction).rgb, 1.0);
+}

shaders/refractive_frag.glsl

@@ -0,0 +1,19 @@
+#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);
+}