osgMulitiplerendertargets sample 中fbo使用【HTC VIVE开发中应用】
osgmultiplerendertargets.cpp
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// now create the camera to do the multiple render to texture
{
osg::Camera* camera = new osg::Camera;
// set up the background color and clear mask.
camera->setClearColor(osg::Vec4(0.1f,0.1f,0.3f,1.0f));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// the camera is going to look at our input quad
camera->setProjectionMatrix(osg::Matrix::ortho2D(0,1,0,1));
camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
camera->setViewMatrix(osg::Matrix::identity());
// set viewport
camera->setViewport(0, 0, tex_width, tex_height);
// set the camera to render before the main camera.
camera->setRenderOrder(osg::Camera::PRE_RENDER);
// tell the camera to use OpenGL frame buffer objects
camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
// attach the textures to use
for (int i=0; i<NUM_TEXTURES; i++) {
if (useMultiSample)// 使用多重渲染方式消除锯齿现象
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0+i), textureRect[i], 0, 0, false, 4, 4);
else
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0+i), textureRect[i]);
}
// we can also read back any of the targets as an image, modify this image and push it back
// 绑定一张image获取fbo渲染结果
if (useImage) {
// which texture to get the image from
const int tex_to_get = 0;
osg::Image* image = new osg::Image;
if (useHDR) {
image->allocateImage(tex_width, tex_height, 1, GL_RGBA, GL_FLOAT);
} else {
image->allocateImage(tex_width, tex_height, 1, GL_RGBA, GL_UNSIGNED_BYTE);
}
// attach the image so its copied on each frame.
camera->attach(osg::Camera::BufferComponent(osg::Camera::COLOR_BUFFER0 + tex_to_get), image);
camera->setPostDrawCallback(new MyCameraPostDrawCallback(image));
// push back the image to the texture
textureRect[tex_to_get]->setImage(0, image);
}
// add the subgraph to render
camera->addChild(cam_subgraph);
parent->addChild(camera);
}