Re: Rendering a 3-d texture

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Angus Dorbie (dorbie++at++multipass.engr.sgi.com)
Wed, 27 Aug 1997 23:24:11 -0700

On Aug 27, 1:28pm, Volz, Bill (wrvo) wrote:
> Subject: Rendering a 3-d texture
> I have a 3-d texture I want to render this cube in a given number of
> planes where each plane is perpendicular to the eye direction (parallel
> to the screen). I can't seem to figure out what transforms I need to do
> this. I've tried Texture matrix and generating the coordinates in
> EYE_LINEAR with a constant box in x,y (0,0->1,0->1,1->0,1->0,0) and the
> z coordinate changing but this rendering stuff that is outside of the
> cube. The current code generates and renders the cube parallel to the
> cube's z's axis not parallel to the screen. I know it can be done, but
> how? I looked at the tex3d program but it renders using the
> texture matrix and just uses that to modify the orientation of the cube,
> not the view direction.
>

I have written a performer based example which shows a simple
volume rendering method using 3D texture coordinates produced
using texgen with appropriate matrix operations for orientation.
I won't post the code here but if anyone wants a copy
they are welcome to it if they ask.

The program is suboptimal w.r.t. clipping the orthogonal
quad polys to the reoriented volume cube and fragment pixel
fragment operation, it zbuffers for example, but this may
be desirable for some applications.

Cheers,Angus.
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