rotation and camera questions

[pipstapa]

I have recently started coding for the iPhone 3Gs, and I'm having a bit of trouble adjusting to the coding environment. Since you cant access any of the regular glFuncs, like glRotate, glTransform etc, do you need to do all this with the matrices? Say I want to rotate an object. Do i have to make a mvp-matrix that I do all functions on for the object and pass that to the vertexshader?

And also, what about the camera? How do you make a cameraobject that you can move around? glViewPort() seems very limited

I appreciate any help

[maximus]

Hi pipstapa,

You should be able to use glRotate3f and glTranslate3f (notice the 3f). I have used them in my OpenGL ES game.

glViewport is not what you use for a camera object in the sense you're thinking of. glViewport just tells OpenGL what your screen is like, such as the width and height of it.

Camera transformations are done on the ModelView matrix, the same matrix you use for positioning/rotating models.

You want to use something like gluLookAt for your camera to get started. But OpenGL ES doesn't have it, so someone has written it for you here:
iPhone Development: gluLookAt()

Please look up the functions carefully in the OpenGL ES specification on Google, making sure you're passing the right arguments and whatnot.

Good luck!