FBObject

FrameBuffer Object (FBO)

   package com.jogamp.opengl;

Creating FBO

   final FBObject fbo = new FBObject(); // Create FrameBuffer
   final GL2ES2 gl = GLContext.getCurrentGL().getGL2ES2();
   fbo.reset(gl, width, height); // int width, height - size of FBO, can be resized with the same call
   // With MSAA:
   // fbo.reset(gl, width, height, sampleNum, true); // int width, height, sampleNum - size/sampleNum of FBO, can be resized with the same call
   fbo.attachTexture2D(gl, 0, true); // Create GL_TEXTURE_2D texture which can be used as sampler2D at the shader code
   // Created texture will be bound to FBO's GL_COLOR_ATTACHMENT0 (see the second parameter 0)
   fbo.attachRenderbuffer(gl, Attachment.Type.DEPTH, 32); // Create depth buffer (if required)
   fbo.unbind(gl); // See Note-3 for use with MSAA. Unbind FrameBuffer (You will probably want to make bind() - render - unbind() loop later on)

Render to FBO

   fbo.bind(gl);
   // Render scene as usual
   fbo.unbind(gl); // See Note-3 for use with MSAA
   

Render from FBO to another FBO

Imagine we have 2 FBO, source and target. Source FBO must have TextureAttachment (created with attachTexture2D(), for example)

   FBObject source;
   FBObject target;

Using low-level texture binding:

   final TextureAttachment tex0 = (TextureAttachment) source.getColorbuffer(0);
   target.bind(gl); // Starting rendering to target FBO
   gl.glActiveTexture(GL2.GL_TEXTURE0);
   gl.glEnable(GL2.GL_TEXTURE_2D); // Should not call this for CORE profiles, i.e. ES2, GL3, ..
   gl.glBindTexture(GL2.GL_TEXTURE_2D, tex0.getName()); // See Notes 1, 2. Binding source FBO's TextureAttachment as GL_TEXTURE_2D
   // Here you can render something using source texture as GL_TEXTURE0
   // For example, you can enable shader with some filter, which makes use of sampler2D and render a fullscreen quad. 
   target.unbind(gl); // See Note-3 for use with MSAA. Unbind FBO

Render from FBO to screen

   final TextureAttachment tex0 = (TextureAttachment) source.getColorbuffer(0);
   gl.glActiveTexture(GL2.GL_TEXTURE0);
   gl.glEnable(GL2.GL_TEXTURE_2D);  // Should not call this for CORE profiles, i.e. ES2, GL3, ..
   gl.glBindTexture(GL2.GL_TEXTURE_2D, tex0.getName()); // See Notes 1, 2. Binding source FBO's TextureAttachment as GL_TEXTURE_2D
   // Here you can just render a fullscreen quad to show FBO content, or do something more exciting

Notes

• Note-1: One could also call FBObject.use(gl, ta) w/ TextureAttachment ta instead of FBObject.unbind(gl)/FBObject.syncSamplingSink(gl)
• Note-2: Calls to FBObject.use(..)/FBObject.unuse() will unbind current buffer
• Note-3: When using MSAA, you must use fbo.syncSamplingSink(gl) instead of fbo.unbind(gl). Call to syncSamplingSink ensures MSAA buffers are blitted to the FBO sink, can be called by non MSAA as well (NOP). Will always unbind FBO.

Demos/Tests

• TestFBOMix2DemosES2NEWT.java