Hi, J.P.
the camera isn't rendering to a texture. In my programme, camera is set
to be prerender, render target is FRAME_BUFFER_OBJECT, I attach the
camera to an image, in order to get the bufferdata via image. the image
data type is allocated as GL_FLOAT.
Related setup details are listed below.
// renderTarget
osg::Camera::RenderTargetImplementation renderTargetImplementation;
renderTargetImplementation = osg::CameraNode::FRAME_BUFFER_OBJECT;
// shader program
osg::Program * program = new osg::Program();
program->addShader(osg::Shader::readShaderFile(osg::Shader::FRAGMENT,
fragmentShaderPath));
program->addShader(osg::Shader::readShaderFile(osg::Shader::VERTEX,
vertexShaderPath));
// image
osg::Image * image = new osg::Image();
image->allocateImage((int)XRes, (int)YRes, 1, GL_RGBA, GL_FLOAT);
//camera
osg::ref_ptr<osg::CameraNode> camera(new osg::CameraNode());
camera->setProjectionMatrixAsFrustum(-tan(YawView * math::D2R * 0.5),
tan(YawView * math::D2R * 0.5), -tan(PitchView * math::D2R * 0.5),
tan(PitchView * math::D2R * 0.5),zNear, zFar);
camera->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
camera->setViewport(0, 0, XRes, YRes);
camera->setClearColor(osg::Vec4(1000.0f, 1000.0f, 1000.0f, 1000.0f));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
camera->setViewMatrix(osg::Matrix::lookAt(osg::Vec3d(0, 0, 1.0f),
osg::Vec3d(-10.0f, 0.0f, 0), osg::Vec3d(0, 0, 1)));
camera->setRenderOrder(osg::CameraNode::PRE_RENDER);
camera->setRenderTargetImplementation(renderTargetImplementation);
camera->attach(osg::CameraNode::COLOR_BUFFER, image);
//read out data
osg::Vec4f * rgbaData = (osg::Vec4f *) (image->data());
for (int h = 0; h < yRes; h++) {
for (int w = 0; w < xRes; w++) {
osg::Vec4f cur =
rgbaData[xRes * h + w];
cout<<"cur[0]="<<cur[0]<<",cur[1]="<<cur[1]<<",cur[2]="<<cur[2]<<",cur[3]="<<cur[3]<<endl;
}
}
Thank you for any advice!
Shuiying
Message: 3
Date: Wed, 18 Jan 2012 09:11:15 +0200
From: "J.P. Delport"<[email protected]>
To: OpenSceneGraph Users<[email protected]>
Subject: Re: [osg-users] Help: wrong ouput from frag shader.
Message-ID:<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi,
what format is the texture you are rendering to? If it is UNSIGNED CHAR
then your data would be discretised.
e.g. 45/255 = 0.176471
jp
On 17/01/2012 21:11, wang shuiying wrote:
Hello,
when I write gl_FragColor = vec4(0.174977,0,0,1) in Frag shader,
then I get through a related image: float Vec4: (0.176471,0,0,1)
so why 0.174977 changed into 0.176471?
I think there should be no process there after per fragment operations
that can change this element in the rendering pipeline. Blend, alphatest
and so on are all disenabled.
Thank you in advance!
Shuiying
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