Hi,
I need to implement some post processing shader effect, based on multipass
shading/rendering processes. In thiss multipass process each shader could have
one or more RTT targets as input and output of the pass.
To realize this i've implemented a render to texture class based on the
osgprerender and osgtexturerectangle examples. This class creates for each
instance a texture rectangle and a FBO POST-Process camera by this way:
void createCamera(osg::ref_ptr<osg::Node> subGraph, unsigned int passPos)
{
m_camera = new osg::Camera;
m_camera->setName("rttCamera");
m_camera->setClearColor(m_clearColor);
m_camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
m_camera->setViewMatrix(osg::Matrix::identity());
m_camera->setViewport(0,0,windowWidth,windowHeight);
// define orthogonal projection
m_camera->setProjectionMatrix(osg::Matrix::ortho2D(0,windowWidth,0,windowHeight));
// bind camera as POST-Process Camera with the position value of the pass
m_camera->setRenderOrder(osg::Camera::POST_RENDER, passPos);
// add subcene to camera to render
m_camera->addChild(subGraph.get());
}
The initialized camera is a member of type osg::ref_ptr<osg::Camera> and the
passPos Parameter defines the pass of the shader.
Each pass is handled as single osg::ref_ptr<osg::StateSet> in a specialised
pass class. For each pass i define the referenced shader and textures which
depends on. So that i have the following object tree structure:
osg::Geometry
osg::Texture2D "Decal"
osg::Texture2D "Normal"
RTT next (my RTTclass)
RectangleTexture
Camera (PRE)
RTT prev(my RTTclass)
RectangleTexture
osg::CameraNode (PRE)
Pass1 "Dot3" (Main)
StateSet
Program
ShaderV
Attributes
Uniform
Uniform
ShaderF
Uniform
Uniform
<-- Decal (in)
<-- Normal (in)
--> Next (out)
Pass2
StateSet
Program
ShaderV
Attributes
Uniform
Uniform
ShaderF
Uniform
Uniform
<-- Next (in)
--> Prev (out to screen (texturized quad))
This works fine, if i use only a single pass shader. In this case the RTT
Texture is rendered to a texturized quad in front of the view. If i use this
RTT as input for the second path, and try to render the output of the second
rtt on the textured quad nothing is shown where the textured quad should be...
I have no idea what could be wrong or what i've overseen... Perhaps i made
somthing conceptionally wrong. Has anyone implemented a multipass shadering
with osg and could me push to the correct sollution?
If you required more code, i will append if i am back from work...
Thanks in advance,
best regards
Chris
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