CODEWITHSUNDEEP
openglgraphicsopengl-3opengl-4stencil-buffer
claudehenry
claudehenry

Reputation: 846

Is the stencil buffer still relevant in modern OpenGL?

Me and a friend have been having an ongoing argument about the stencil buffer. In short I haven't been able to find a situation where the stencil buffer would provide any advantage over the programmable pipeline tools in OpenGL 3.2+. Are there any uses to the stencil buffer in modern OpenGL?

[EDIT]

Thanks everyone for all the inputs on the subject.

Upvotes: 6

Views: 4264

Answers (3)

fieldtensor
fieldtensor

Reputation: 4050

Just to provide one other use case, shadow volumes (aka "stencil shadows") are still very relevant: https://en.wikipedia.org/wiki/Shadow_volume

They're useful for indoor scenes where shadows are supposed to be pixel perfect, and you're less likely to have alpha-tested foliage messing up the extruded shadow volumes.

It's true that shadow maps are more common, but I suspect that stencil shadows will have a comeback once the brain dead Createive/3DLabs patent expires on the zfail method.

Upvotes: -2

karyon
karyon

Reputation: 2557

To add a recent example to Andon's answer, GTA V uses the stencil buffer kinda like an ID buffer to mark the player character, cars, vegetation etc.

It subsequently uses the stencil buffer to e.g. apply subsurface scattering only to the character or exclude him from motion blur.

See the GTA V Graphics Study (highly recommended, it's a great read!)

Edit: sure you can do this in software. But you can do rasterization or tessellation in software just as well... In the end it's about performance I guess. With depth24stencil8 you have a nice hardware-supported format, and the stencil test is most likely faster then doing discards in the fragment shader.

Upvotes: 11

Andon M. Coleman
Andon M. Coleman

Reputation: 43319

It is more useful than ever since you can sample stencil index textures from fragment shaders. It should not even be argued that the stencil buffer is not part of the programmable pipeline.

The depth buffer is used for simple pass/fail fragment rejection, which the stencil buffer can also do as suggested in comments. However, the stencil buffer can also accumulate information about test results over multiple passes. All sorts of logic and counting applications exist such as measuring a scene's depth complexity, constructive solid geometry, etc.

Upvotes: 15

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