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Rotating a cube

Started by w166um Sep 17, 2006 at 8:43 AM 1 replies 1.2k views

Original Post

Sep 17, 2006 at 8:43 AM

I'm working on a simple OpenGL app. I have a cube drawn at the origin. Now I want to implement rotation using the mouse. However i'm having trouble trying to get a fixed coordinate system. For example if I flip the cube upside down and i try to rotate left it rotates right. Could someone please point me in the right direction? I'm fairly new to all this. Thanks in advance.

supervlad

Sep 18, 2006 at 1:18 AM

I'm new to opengl as well, so I'm experienced. But I know that opengl translates, rotates, and scales things cumulatively. For instance, if you're at the origin and move 5 units on x, and then move 3 more units on x you'll be 8 units away from the origin. So my guess is that it has something to do with that, because similar things happen to rotation.

GamerYZ

Sep 18, 2006 at 1:50 AM

I would try something like this:

- store the cube matrix somewhere
- load identity
- check for mouse input and do the rotation if necessary
- glPushMatrix()
- apply the cube matrix to the stack
- draw cube
- if there was new rotation from input, set the cube matrix to the matrix that is on top of the stack
- glPopMatrix()

since it's not tested, I'm not 100% sure it'll work, but it's something I'd try first myself.

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