Hi,
On 03/01/2012 23:39, wang shuiying wrote:
Hello,
(1)to J.P.
the related source code is as following:
// camera and image setup
osg::Camera::RenderTargetImplementation renderTargetImplementation;
renderTargetImplementation = osg::CameraNode::FRAME_BUFFER;
^ If you want FBO, you probably want FRAME_BUFFER_OBJECT here.
osg::Program * program = new osg::Program();
program->addShader(osg::Shader::readShaderFile(osg::Shader::FRAGMENT,
fragmentShaderPath));
program->addShader(osg::Shader::readShaderFile(osg::Shader::VERTEX,
vertexShaderPath));
osg::Image * image = new osg::Image();
image->allocateImage((int)XRes, (int)YRes, 1, GL_RGBA, GL_FLOAT);
osg::ref_ptr<osg::CameraNode> camera(new osg::CameraNode());
camera->setClearColor(osg::Vec4(1000.0f, 1000.0f, 1000.0f, 1000.0f));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera->setRenderOrder(osg::CameraNode::PRE_RENDER);
camera->setRenderTargetImplementation(renderTargetImplementation);
camera->attach(osg::CameraNode::COLOR_BUFFER, image);
OpenGL would happily convert from one render target pixel format on the
GPU to another one on the CPU when transferring data. So you must make
sure that the formats are what you expect. The easiest way is to attach
both a texture and an osg::Image to the camera and explicitly set the
internal texture format and data type. See the osgprerender example. You
can also inspect the code in RenderStage::runCameraSetUp to see exactly
how OSG determines the format of the render target.
Also, if you want values outside of [0.0, 1.0] you must attach to
osg::CameraNode::COLOR_BUFFER0 and use gl_FragData in your shaders.
camera->getOrCreateStateSet()->setAttribute(program, osg::StateAttribute::ON);
// access data (only for instance)
osg::Vec4f * fragments = (osg::Vec4f *)(image->data());
osg::Vec4f color= distances[10];
float color_a= distances[3];
As can be seen from the source code, I attach an image to the camera, and
access data from the image,
I am rendering to an FBO.
I don't think you are rendering to an FBO with the above code.
So would you please give me some advice further?
Thank you very much!
*(2) to Paul*
Refer to (1) of this message, does osg::CameraNode::COLOR_BUFFER imply a RGB
or RGBA buffer
? or it doesn't even matter?
It does not imply anything.
rgds
jp
Thank you very much !
Shuiying
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