Uflenu

05-14-2001, 06:03 AM

Hi everybody,

I'm using glReadPixels and gluUnProject to get the 3D coordinates of all the pixels of a picture (my purpose is to calculate a simulated sonar profile of the scene).

gluUnProject is time consuming, and returns absolute coordinates which I need to convert into new coords relative to the viewpoint.

I guess that this transformation is made twice (once, reversed, inside of the unproject subroutine and once by myself). I think that I would save time if I could directly unproject the winZ, winY, winZ into the viewpoint coordinates system.

The 2 ideas I have are:

- do the unproj myself with a simplified algorithm

- pass modified proj and/or model matrices to the gluUnProject routine

Could somebody help in any of these directions ?

Thanks,

Eric

I'm using glReadPixels and gluUnProject to get the 3D coordinates of all the pixels of a picture (my purpose is to calculate a simulated sonar profile of the scene).

gluUnProject is time consuming, and returns absolute coordinates which I need to convert into new coords relative to the viewpoint.

I guess that this transformation is made twice (once, reversed, inside of the unproject subroutine and once by myself). I think that I would save time if I could directly unproject the winZ, winY, winZ into the viewpoint coordinates system.

The 2 ideas I have are:

- do the unproj myself with a simplified algorithm

- pass modified proj and/or model matrices to the gluUnProject routine

Could somebody help in any of these directions ?

Thanks,

Eric