Jump to content
  • Advertisement
Sign in to follow this  
xujiezhige

Differences bwteen depth-pass and depth-fail stencil shadow in shadow volume

This topic is 2310 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I find depth-pass tech gives wrong stencil buffer if the camera is in the shadow volume when i learn the sample of ShadowVolume in DXSDK.
But the depth-fail tech works at all circumstances whether the camera is in the shadow or not.

Can you represent your opinion about it ?

Share this post


Link to post
Share on other sites
Advertisement
Well, yes that‘s true. smile.png

The classical z-pass technique decrements the stencil value when a front face is rendered. If that’s not visible, well, then shadowed and lit areas are reversed… Everything that should not be in shadow suddenly is (and vice versa).

Carmack’s z-fail shadows can handle this case, but unfortunately they are a slower, since the GPU can’t do hierarchical z-culling anymore (c.f. Persson, "Depth In-depth", page 6). If your shadow casting geometries are not too complex, don’t worry.

Cheers!

Share this post


Link to post
Share on other sites
Another reason z-fail is more expensive is because you have to render a lot more triangles for the endcaps. You should you z-pass as much as possible, and use z-fail only when necessary. You can determine when z-fail is necessary as described here:

http://www.gamasutra.com/view/feature/2942/the_mechanics_of_robust_stencil_.php?page=4

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

Participate in the game development conversation and more when you create an account on GameDev.net!

Sign me up!