Hi Delport,
Reasons for rendering the scene to two textrues
With key press event i may want to show the texture using the HUD that have not
gone through any operation. If i do any post processing on the texture the
initial texture value is lost. I want to preserve it. This is why i render the
same scene to two texture.
One Texture that contains the main scene and other texture also contains the
main scene but will go through further operation.
All the rendering are in PRE_ORDER except the HUD camera. HUD camera is using
the NESTED_RENDER.
When the HUD camera is viewing any texture it is accessing the texture as
follows:
***************************************************************************'
................................
..............................
//the scene is passed to the followng class
bp = new BlurPass(subgraph,clearColour);
distortionNode->addChild(bp->getRoot().get());
...............................
//the following function is accessing the texture by checking first the active
switch node
stateset->setTextureAttributeAndModes(0,
bp->getOutputTexture().get(),osg::StateAttribute::ON);
...................................
osg::ref_ptr<osg::Texture2D> BlurPass::getOutputTexture() const
{
int out_tex = _ActiveBranch;
return _ProcessPass[out_tex]->getOutputTexture();
}
//inside the BlurPass class i call the following function that make one switch
enables while making the other disabled - in other words flip fllop
void BlurPass::activateBranch()
{
//GET THE current activate branch
int onb = _ActiveBranch;
osg::notify(osg::NOTICE) << "on bit " << onb << std::endl;
//get teh current inactive branch
int offb = (onb == 1) ? 0 : 1;
osg::notify(osg::NOTICE) << "off bit " << offb << std::endl;
//make the active switch on
_BranchSwitch[onb]->setAllChildrenOn();
//make the inactive switch off
_BranchSwitch[offb]->setAllChildrenOff();
}
void BlurPass::flip()
{
_ActiveBranch = (_ActiveBranch == 1) ? 0 : 1;
osg::notify(osg::NOTICE)<<"active branch "<< _ActiveBranch << std::endl;
activateBranch();
}
BlurPass::BlurPass(osg::Node *scene, const osg::Vec4 &clearColor)
:_SubGraph(scene),
_ClearColor(clearColor)
{
//pre-define the texture
//width and height, the very same size
//we preserve all over the scene
_TextureWidth = 1280;
_TextureHeight = 1280;
//initially the shader is inactive
shaderFlag = false;
_RootGroup = new osg::Group;
//initialize the texture where we
//shall render the initial scene
createInputTexture();
//initialize the 2 output textures
//which will be flipped with keypress
//for multipass blurring
createOutputTextures();
//camera renders the scene to the 0-indexed texture
//that will be goiing through the blur phase in the process pass
setupCamera();
//create two switch to do the flip-flop
_BranchSwitch[0] = new osg::Switch;
_BranchSwitch[1] = new osg::Switch;
//add the camera and the two switches
//camera that renders the scene to the texture
_RootGroup->addChild(_Camera.get());
_RootGroup->addChild(_BranchSwitch[0].get());
_RootGroup->addChild(_BranchSwitch[1].get());
//initialize the active switch
_ActiveBranch = 0;
//activate the switch based on the
//current active branch flag
activateBranch();
//we have both input and output textures initialized and
//the _InOutTextureBlur[0] get the scene rendering that will
//going through the blur operation
_ProcessPass[0] = new
ProcessPass(_OutTextureBlur[0].get(),_OutTextureBlur[1].get(),
_TextureWidth,_TextureHeight);
_ProcessPass[1] = new
ProcessPass(_OutTextureBlur[1].get(),_OutTextureBlur[0].get(),
_TextureWidth,_TextureHeight);
_BranchSwitch[0]->addChild(_ProcessPass[0]->getRoot().get());
_BranchSwitch[1]->addChild(_ProcessPass[1]->getRoot().get());
}
//setup the render to texture camera
//the following function renders the initial scene to 2 textures
void BlurPass::setupCamera()
{
_Camera = new osg::Camera;
_Camera->setClearColor(_ClearColor);
_Camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//just inherit the main cameras view
_Camera->setReferenceFrame(osg::Transform::RELATIVE_RF);
_Camera->setProjectionMatrix(osg::Matrixd::identity());
_Camera->setViewMatrix(osg::Matrixd::identity());
//set the viewport according to the value texture width and texture height
_Camera->setViewport(0,0,_TextureWidth,_TextureHeight);
//RENDER to texture before the main camera
_Camera->setRenderOrder(osg::Camera::PRE_RENDER);
//USE THE frame buffer object where supported
_Camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
//the camera with the relative frame renders to the input texture - index 0
//this texture will be input for the process pass
_Camera->attach(osg::Camera::COLOR_BUFFER0,_InputTexture.get());
_Camera->attach(osg::Camera::COLOR_BUFFER1,_OutTextureBlur[0].get());
//the sent subgraph will be rendered to the texture
if(_SubGraph.valid())
_Camera->addChild(_SubGraph.get());
else
osg::notify(osg::FATAL)<< "Scene was not even created, camera has
nothing to work on"<<std::endl;
}
Inside the constructor i initialize the _ActiveBranch to 0 so the first Switch
is enabled initially, i get the first pass operational. With key press event i
am enabling the second switch enabled while making the first one disabled. And
then the screen freezes. Then again if i press the key the switch 0 is enabled
, i can see the single blur pass again.
****************************************************************************
If there is any flaw in design logic, please provide some hint .
Thank you!
Regards
Sajjadul
------------------
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http://forum.openscenegraph.org/viewtopic.php?p=34762#34762
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