Quick commit of a broken setup that doesn't work.

27-instancing/shaders/26-frag.glsl

@@ -0,0 +1,17 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec3 Normal;
+in vec3 FragPos;
+in vec2 TexCoords;
+
+uniform vec3 cameraPos;
+uniform samplerCube skybox;
+
+void main()
+{
+  float ratio = 1.0/1.52;
+  vec3 I = normalize(FragPos - cameraPos);
+  vec3 R = refract(I, normalize(Normal), ratio);
+  FragColor = vec4(texture(skybox, R).rgb, 1.0);
+}