Hi,
I'd suggest attaching a texture with a GL_RGBA32F_ARB internal format to
the camera as well (in addition to the image). I'm not sure you are
getting a float FBO. See the osgprerender example with the --hdr switch.
jp
On 29/11/2011 16:12, wang shuiying wrote:
Hallo,
I want to simulate laser scanner using osg camera. In Fragment shader
the color information is converted into position information. And then
the position information is accessed from this Fragment to be used to
draw points in a view. But the points are not so accurate, as it is
shown in the attached picture, which is composed of 11 cameras. The
important codes are:
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(xRes, yRes, 1, GL_RGBA, GL_FLOAT);
osg::ref_ptr<osg::CameraNode> camera(new osg::CameraNode());
camera->setComputeNearFarMode(osg::Camera::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->setProjectionMatrixAsFrustum(-tan( viewYaw), tan(viewYaw),
-tan(viewPitch), tan(viewPitch), zNear,zFar);
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);
camera->getOrCreateStateSet()->setAttribute(program,
osg::StateAttribute::ON);
In vertex Shader, I write:
void main()
{
x=(gl_ModelViewMatrix * (gl_Vertex - vec4(0.0,0.0,0.0,0.0))).x;
y=(gl_ModelViewMatrix * (gl_Vertex - vec4(0.0,0.0,0.0,0.0))).y;
z=(gl_ModelViewMatrix * (gl_Vertex - vec4(0.0,0.0,0.0,0.0))).z;
gl_Position = ftransform();
}
in Fragment shader, I write:
gl_FragColor = vec4(abs(z/100),abs(x/17),abs(y/4),0.2);
And I when get the position information, I will multiply them with the
corresponding factors.
However, the points are not that accurate. I seems that the Fragment
shader does not calculate the point one by one, but assign a certain
value to a certain amount of points.
Can anybody give some advice?
Thanks in advance!
Shuiying
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