Cleanup: code comment for view3d_viewmatrix_set

source/blender/editors/space_view3d/view3d_view.c

@@ -1191,6 +1191,11 @@ void view3d_viewmatrix_set(
 			vec[2] = 0.0f;
 
 			if (rect_scale) {
+				/* Since 'RegionView3D.winmat' has been calculated and this function doesn't take the 'ARegion'
+				 * we don't know about the region size.
+				 * Use 'rect_scale' when drawing a sub-region to apply 2D offset,
+				 * scaled by the difference between the sub-region and the region size.
+				 */
 				vec[0] /= rect_scale[0];
 				vec[1] /= rect_scale[1];
 			}