TexturesAndFbos: Changes and Notes

[simongeilfus]

https://github.com/simongeilfus/Cinder/tree/TexturesAndFbos

Changes / Additions

gl/Texture

• [x] gl::TextureBase::Format::setSamples
• [x] gl::TextureBase::Format::getSamples
• [x] gl::Texture2d::Format::samples
• [x] gl::Texture3d::Format::samples

  gl/Fbo

• [x] gl::Fbo::createEmpty (see https://github.com/cinder/Cinder/issues/1191)
• [ ] gl::Fbo multisampling support for texture2dArray (see https://github.com/cinder/Cinder/issues/1191)
• [x] gl::Fbo::Format::depthTexture doesn't support GL_DEPTH_STENCIL format (see https://github.com/cinder/Cinder/issues/1501)
• [ ] gl::Fbo better support for textureCubemap (see https://github.com/cinder/Cinder/issues/1320 and https://forum.libcinder.org/#Topic/23286000002501045)
• [x] gl::Fbo better support for texture3d and texture2dArray (see https://github.com/cinder/Cinder/issues/1191)
• [x] gl::Fbo::attach
• [ ] gl::Fbo::attach multisampling support
• [ ] gl::Fbo::Format option to switch to texture based multisampling
• [x] static gl::Fbo::checkStatus
• [x] Fix for "gl::Fbo default depth-stencil renderbuffer is created twice on desktop" (see https://github.com/cinder/Cinder/issues/1503)

  gl/wrapper

• [x] gl::framebufferRenderbuffer
• [x] gl::framebufferTexture
• [x] gl::frameBufferTextureLayer
• [x] gl::drawBuffers( const std::vector<GLenum> &bufs );
• [x] gl::getMaxSamples
• [x] gl::getMaxColorTextureSamples
• [x] gl::getMaxDepthTextureSamples

  gl/scoped

• [x] gl::ScopedDrawBuffers (see https://github.com/cinder/Cinder/issues/736)

  gl/Environment

• [x] gl::Environment::supportsTextureMultisample
• [x] gl::Environment::supportsTextureStorageMultisample

  gl/platform

• [x] CINDER_GL_HAS_TEXTURE_MULTISAMPLE
• [x] CINDER_GL_HAS_TEXTURE_2D_STORAGE_MULTISAMPLE
• [x] CINDER_GL_HAS_TEXTURE_3D_STORAGE_MULTISAMPLE

  tests/_opengl

• [ ] Tests on Linux, MacOS, iOS and GL ES 3 !!!
• [x] EmptyFbo
• [ ] Separate texture multisample tests from EmptyFbo
• [ ] Layered Rendering

  Related pull requests

• Added mipmap support for 2d texture arrays : https://github.com/cinder/Cinder/pull/1432
• Texture*::getFormat() const : https://github.com/cinder/Cinder/pull/1217

  Notes

• Could deprecate gl::Fbo::getMaxSamples() to gl::getMaxSamples() as it's not onle related to Fbos (found only two breaking changes in Fbo.cpp#L81, nothing in samples)
• maximum number of samples of a texture is not GL_MAX_SAMPLES but GL_MAX_COLOR_TEXTURE_SAMPLES and GL_MAX_DEPTH_TEXTURE_SAMPLES ... No idea if those might return different values on other gpus.
• made gl::Fbo::checkStatus() static
• should we have both ScopedDrawBuffers and ScopedDrawBuffer or one class is enough for both glDrawBuffer and glDrawBuffers?

  Textures Multisample support :

Function	Target	Desktop	ES	Cinder Proposed Feature Name
glTexImage2DMultisample	GL_TEXTURE_2D_MULTISAMPLE	GL3.2		CINDER_GL_HAS_TEXTURE_MULTISAMPLE
glTexImage3DMultisample	GL_TEXTURE_2D_MULTISAMPLE_ARRAY	GL3.2		CINDER_GL_HAS_TEXTURE_MULTISAMPLE
glTexStorage2DMultisample	GL_TEXTURE_2D_MULTISAMPLE	GL4.3	ES3.1	CINDER_GL_HAS_TEXTURE_2D_STORAGE_MULTISAMPLE
glTexStorage3DMultisample	GL_TEXTURE_2D_MULTISAMPLE_ARRAY	GL4.3		CINDER_GL_HAS_TEXTURE_2D_STORAGE_MULTISAMPLE

[thyrrestrup]

It would be a very welcome update to get at least some of these changes merged into Cinder. Nice work!

[totalgee]

Thanks, it's great Fbo is getting some love. (-;

Not sure this is useful "generally", but for my purposes it would have been useful to have:

• ability to bind the resolved part of a multisampled Fbo, using the Cinder Fbo API. Normally, when you bindFramebuffer() (it seems to assume you're binding in order to draw to it, even if you pass the READ target), it binds the multisampled framebuffer (which is what getId() returns if the Fbo has multisampling). Luckily, the method getResolveId() existed, so I could do what I needed directly with raw OGL calls (as long as I was careful to restore Cinder's framebuffer binding state after changing it under the covers).

• related to the above: When you call bindFramebuffer() with the GL_READ_FRAMEBUFFER target, it perhaps shouldn't call markAsDirty() (ref), since you're only going to be using it as a source.

BTW, above, when I say "what I needed," I mean: the ability to blit the resolved part of a multisampled Fbo to a different (non-multisampled) Fbo. In my case, I was doing that using an OpenGL extension blit function (glMulticastBlitFramebufferNV()) to transfer it between GPUs.

In my case, I'm not using any extra (color) attachments, so I didn't need to change read/draw buffers for the Fbo blit stuff I was doing (using glDrawBuffers() or glReadBuffer()). However, it might be necessary in some cases, if you had multiple attachments. Is it possible to get/enumerate the attachments (mAttachments* entries) once you've created an Fbo? Doesn't seem to be. (NOTE: This is not important for me in this case, mainly just a curiosity...don't worry about it!)

I'm not sure any of this warrants complicating Fbo -- e.g. for different bind cases for READ vs DRAW -- but just thought I'd add my comments here in case they are useful or spark any thoughts. Thanks!