# Thread: BackFace Culling on Vincent

1. ## BackFace Culling on Vincent

Hi there,

Anyone know what algorithm of backface culling the Vincent implements?
Im developing my own backface culling and i wanna know what algorithm is behind the Vincent.

thanks

Wendel B Silva

2. ## Re: BackFace Culling on Vincent

Originally Posted by cobrahc
Anyone know what algorithm of backface culling the Vincent implements?
Im developing my own backface culling and i wanna know what algorithm is behind the Vincent.
It's using the algorithm described in the OpenGL ES API specification.

- HM

3. Hi again.

Sorry, reading the specification of the OpenGL ES 1.1.10 Common/Common-Lite i havent find how its coded. Maybe i looked in the wrong document or something like that.
In this document, in the session about cullface, only say how you determine the polygon signed area to see if its CW or CCW.

The backface culling use this signed area to cull the face? How this work? Can you point me any text or something about?

Sorry to bother you and thanks for your time

Best regards,

Wendel B Silva

4. Originally Posted by cobrahc
only say how you determine the polygon signed area to see if its CW or CCW.
The backface culling use this signed area to cull the face
This is correct.

What is your question?

- HM

5. The test would be simple, testing the signal, only if the camera isnt changed. But since i change the position of the camera, the signal have to be recalculated.. is that right?

But i think the formula i saw in the specification take in consideration that the observer its in the 0,0,0 (XYZ)

6. Originally Posted by cobrahc
The test would be simple, testing the signal, only if the camera isnt changed. But since i change the position of the camera, the signal have to be recalculated.. is that right?

But i think the formula i saw in the specification take in consideration that the observer its in the 0,0,0 (XYZ)
Don't know if it's correct, but you should apply backface culling in camera-space (eye-space), where the camera is in the origin of the coordinate system. It ease the calculations

7. Yes, that help.
Thanks

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•