With glRotate(90, 0.0, 0.1, 0.0) a cube (for example) is rotated with 90 degrees around oy. But this coordinate system is linked to the cube; it rotates itself together with the cube. I want to use another coordinate system: as I sit down on the chair in front of my computer and I look to the screen, OX is a horizontal line on the screen and OY is a vertical line on the screen. The cross point between them is at the left-down corner of the monitor. If the cube is in a random position (ox, oy and oz have a random orientation), how do I rotate it around OX? What about OY? Another question: how do I modify the speed of rotation? And my last question so far: how do I catch with GLUT that event when all 3 mouse buttons are pressed simultaneously? Thanks!