Add framebuffer resize callback

src/main.cc

@@ -56,6 +56,14 @@ GLuint g_program_id = 0;
 static GLuint translate_unif;
 static GLuint rotate_unif;
 
+void framebuffer_size_callback(GLFWwindow* window, int width, int height)
+{
+    // make sure the viewport matches the new window dimensions; note that width and 
+    // height will be significantly larger than specified on retina displays.
+    glViewport(0, 0, width, height);
+    // Re-render the scene because the current frame was drawn for the old resolution
+}
+
 static void init_shaders() {
     dbg_log("Initialising shaders");
 
@@ -134,6 +142,7 @@ int main() {
 
     // Set up the key handler
     glfwSetKeyCallback(w, key_callback);
+    glfwSetFramebufferSizeCallback(w, framebuffer_size_callback);
 
     init_opengl();