Move light around the scene

shaders/vert.glsl

@@ -1,11 +1,18 @@
 #version 330 core
 
 layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
 
+out vec3 vert_normal;
+out vec3 frag_position;
+
+uniform mat3 normal_mat;
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 projection;
 
 void main() {
-  gl_Position = projection * view * model * vec4(position, 1.0);
+  vert_normal   = normal_mat * normal;
+  frag_position = vec3(model * vec4(position, 1.0));
+  gl_Position   = projection * view * model * vec4(position, 1.0);
 };