View Full Version : Difference between Viewplane & Near plane

10-09-2008, 12:42 AM
I am a little confused about this, with special regard to ray tracing, and perspective projection.

10-09-2008, 07:37 PM
I'm also confused about the projection transformation sequence
M = N S H ..

I get H. But what exactly happens in the S stage, is this when the size of objects is changed due to their distance from the camera?

10-10-2008, 04:07 AM
AFAIK, near/far planes are just clipping plane. Then, the view plane can be placed wherever you want. In the OpenGL case, looking at the glFrustum spec (http://www.opengl.org/sdk/docs/man/xhtml/glFrustum.xml), the view plane is like the near plane.

For the second question, could you elaborate a bit more? What does N, S, H notation mean?

10-10-2008, 03:56 PM
Ah ok. That what I thoguht, I thought the viewplane would just lie on the near plane.

M = N S H . = sequence of matrix multiplications for making perpsective projection. shearing (h) i get, it just ensures the frustrum is on the middle of the z axis.

But i dont really get the scaling stage, is there where the size of objects is adjusted according to their dist from the camera?