[osg-users] Render multiple PRE_RENDER cameras to FBO

[Voerman, L.]

Hi Ivar,
Your call to Camera::attach is wrong, requesting anything other than 0 for
multisampleSamples will cause the setup to fail.

backgroundCamera->attach(osg::Camera::COLOR_BUFFER, tex.get(), 0, 0, false,
0, 0);
sceneCamera->attach(osg::Camera::COLOR_BUFFER, tex.get(), 0, 0, false, 0,
0);

Laurens.


On Tue, Nov 13, 2018 at 4:41 PM ivar out <ivarout at gmail.com> wrote:

> Hi,
>
> I'm having trouble properly rendering a couple of cameras to an FBO. I
> have two PRE_RENDER cameras that use a FBO and render to a texture. The
> color buffer seems to be reset before rendering the second camera though.
> This is my code:
>
> Code:
>
> osg::Group* root = new osg::Group;
>
> osg::Camera* backgroundCamera = new osg::Camera;
> osg::Camera* sceneCamera = new osg::Camera;
> osg::Camera* finalCamera = new osg::Camera;
>
> root->addChild(backgroundCamera);
> root->addChild(sceneCamera);
> root->addChild(finalCamera);
>
> //-----------------------------------------
> // create texture to render to
> //-----------------------------------------
> osg::ref_ptr<osg::Texture2D> tex = new osg:
> tex->setSourceType(GL_FLOAT);
> tex->setSourceFormat(GL_RGBA);
> tex->setInternalFormat(GL_RGBA);
> tex->setTextureSize(512, 512);
>
> //-------------------------------------------------------------------
> // add geometry to background camera
> //-------------------------------------------------------------------
> osg::Geometry* background = osg::createTexturedQuadGeometry(osg::Vec3(),
> osg::Vec3(0, 1.0f, 0), osg::Vec3(1.0f, 0, 0));
> osg::ref_ptr<osg::Vec4Array> colors = new osg::Vec4Array;
> colors->push_back(osg::Vec4(1.0, 1.0, 1.0, 1.0));
> colors->push_back(osg::Vec4(1.0, 1.0, 1.0, 1.0));
> colors->push_back(osg::Vec4(0, 0, 0, 1.0f));
> colors->push_back(osg::Vec4(0, 0, 0, 1.0));
> background->setColorArray(colors.get());
> background->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
> osg::Geode* geode = new osg::Geode;
> geode->addChild(background);
> backgroundCamera->addChild(geode);
>
>
> backgroundCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
> backgroundCamera->setViewport(0, 0, tex->getTextureWidth(),
> tex->getTextureHeight());
> backgroundCamera->attach(osg::Camera::COLOR_BUFFER, tex.get(), 0, 0, true,
> 512, 512);
> backgroundCamera->setRenderOrder(osg::Camera::PRE_RENDER, 0);
> backgroundCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
> backgroundCamera->setProjectionMatrixAsOrtho2D(0.0f, 1.0f, 0.0f, 1.0f);
> backgroundCamera->getOrCreateStateSet()->setMode(GL_LIGHTING, FALSE);
> backgroundCamera->setClearMask(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
> backgroundCamera->setClearColor(osg::Vec4(0, 0, 0, 1));
>
> //-------------------------------------------------------------------
> // CREATE Camera to display scene
> //-------------------------------------------------------------------
> sceneCamera->setRenderOrder(osg::Camera::PRE_RENDER, 1);
> osg::Node* node =
> osgDB::readNodeFile("C:\\Software\\OpenSceneGraph-3.6.0\\Models\\cessna.osg");
> sceneCamera->addChild(node);
> sceneCamera->setViewMatrixAsLookAt(osg::Vec3(100, 0, 0), osg::Vec3(),
> osg::Vec3(0, 0, 1));
> sceneCamera->setClearMask(GL_DEPTH_BUFFER_BIT); //don't clear color buffer
> please
>
> sceneCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
> sceneCamera->attach(osg::Camera::COLOR_BUFFER, tex.get(), 0, 0, true, 512,
> 512);
> sceneCamera->setViewport(0, 0, tex->getTextureWidth(),
> tex->getTextureHeight());
>
> //-------------------------------------------------------------------
> // CREATE Camera to display texture
> //-------------------------------------------------------------------
> finalCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
> finalCamera->setProjectionMatrix(osg::Matrix::ortho2D(0, 1.0f, 0, 1.0f));
> osg::Geometry* geom = osg::createTexturedQuadGeometry(osg::Vec3(),
> osg::Vec3(1.0f, 0.0f, 0.0f), osg::Vec3(0.0f, 1.0f, 0.0f));
> osg::ref_ptr<osg::Geode> quad = new osg::Geode;
> quad->addDrawable(geom);
> finalCamera->addChild(quad.get());
>
> // add shaders that draw the texture on the quad
> osg::ref_ptr<osg::Program> program = new osg::Program;
> program->addShader(osgDB::readShaderFile("shader.frag"));
> program->addShader(osgDB::readShaderFile("shader.vert"));
> osg::StateSet* stateset = finalCamera->getOrCreateStateSet();
> stateset->setTextureAttributeAndModes(0, tex.get());
> stateset->setAttributeAndModes(program.get());
> stateset->addUniform(new osg::Uniform("myTexture", 0));
>
> osgViewer::Viewer viewer;
> viewer.setSceneData(root);
> return viewer.run();
>
>
>
>
> Either the background or scene camera can correctly be rendered to the FBO
> (by commenting the other out) but not both at the same time. Does anyone
> understand why this doesn't work? When I render to FRAME_BUFFER it works
> perfectly fine, but I figured since I don't want the texture rendered on
> screen an FBO would be a more efficient option perhaps?
>
> Thanks!
>
> Cheers,
> ivar
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=75191#75191
>
>
>
>
>
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