Question

我正在尝试使用Open Scene Graph 3.4.0在http://ogldev.atspace.co.uk/www/tutorial35/tutorial35.html上的35-37教程中实现Deferred Shading

现在，我正在努力让模板正确传递，所以我尽可能地简化了我的代码。结果，现在我正在使用三个摄像头：

一个RTT相机，用于位置，法线和颜色纹理以及写入深度缓冲区。
使用深度测试结果将一个模板相机（设置为片段着色器中没有颜色输出的RTT相机）写入模板缓冲区
单点照相机（设置为HUD照相机），使用延迟着色并设置为仅在模板缓冲区不为0的位置写入。

当我尝试使用点光源相机显示深度缓冲区时，它可以工作。当我将pointLightCamera的clear mask设置为STENCIL_BUFFER_BIT并将模板清除设置为1时，它会显示所有内容。将其设置为0时，它不显示任何内容。当我在pointLightCamera中禁用清除设置（因为它们应该是这样）并为模板相机中的模板缓冲区启用任何清除设置时，它都没有任何效果。 stencilFunc和stencilOperation按照教程中的设置进行设置。

当我启动程序时，它不会显示任何内容（因此所有模板值都为0）。这导致我得出结论，我的模板摄像机实际上没有写入模板缓冲区，但我不知道为什么，我无法找到帮助osg示例或互联网论坛，我已经尝试了我能想到的一切

以下是我对相机和观察者的设置（rttCamera将我的场景groupnode作为一个孩子，其中包含一个模型，stencilCamera有一个球体模型作为光量的孩子，我的pointLightCamera有一个screenQuad作为子）。

texDepth->setTextureSize(1024, 1024);
texDepth->setInternalFormat(GL_DEPTH24_STENCIL8_EXT);
texDepth->setSourceFormat(GL_DEPTH_STENCIL_EXT);
texDepth->setSourceType(GL_UNSIGNED_INT_24_8_EXT);

osg::ref_ptr<osg::Texture2D> texColor = createTexture();
osg::ref_ptr<osg::Texture2D> texPosition = createTexture();
osg::ref_ptr<osg::Texture2D> texNormal = createTexture();

//1. pass camera and set up
osg::ref_ptr<osg::Camera> rttCamera = createRTTCamera(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER, texDepth, false);

rttCamera->setRenderOrder(osg::Camera::PRE_RENDER, 0);
rttCamera->attach(osg::Camera::COLOR_BUFFER0, texColor);
rttCamera->attach(osg::Camera::COLOR_BUFFER1, texPosition);
rttCamera->attach(osg::Camera::COLOR_BUFFER2, texNormal);
rttCamera->setClearColor(osg::Vec4(0.0, 0.0, 0.0, 0.0));

osg::ref_ptr<osg::Stencil> rttStencil = new osg::Stencil;
rttStencil->setWriteMask(0);
rttCamera->getOrCreateStateSet()->setAttribute(rttStencil, osg::StateAttribute::ON);

rttCamera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

osg::ref_ptr<osg::StateSet> ss = rttCamera->getOrCreateStateSet();
osg::ref_ptr<osg::Program> rttProg = new osg::Program;
osg::Shader* vertShader = osgDB::readShaderFile("pass1.vert");
osg::Shader* fragShader = osgDB::readShaderFile("pass1.frag");
rttProg->addShader(vertShader);
rttProg->addShader(fragShader);
ss->setAttributeAndModes(rttProg.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

osg::ref_ptr<osg::BlendFunc> bf = new osg::BlendFunc;
bf->setFunction(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
ss->setAttributeAndModes(bf, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

rttCamera->addChild(scene.get());

//2. pass: stencil pass camera and set up
osg::ref_ptr<osg::Camera> stencilCamera = createRTTCamera(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER, texDepth, false);//createHUDCamera(0.0, 1.0, 0.0, 1.0);//
stencilCamera->setRenderOrder(osg::Camera::PRE_RENDER, 2);

stencilCamera->attach(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER, texDepth);//depth buffer was filled by rttCamera
stencilCamera->getOrCreateStateSet()->setMode(GL_STENCIL_TEST, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
stencilCamera->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);  //depth test result will fill stencil buffer
osg::ref_ptr<osg::Depth> depth = new osg::Depth;
depth->setWriteMask(false);         //depth test is needed to compare scene to light volume, but light volume must not write into depth buffer
stencilCamera->getOrCreateStateSet()->setAttribute(depth, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

stencilCamera->getOrCreateStateSet()->setMode(GL_CULL_FACE, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);
stencilCamera->setClearMask(GL_STENCIL_BUFFER_BIT);

osg::ref_ptr<osg::StencilTwoSided> stencilWrite = new osg::StencilTwoSided;
stencilWrite->setFunction(osg::StencilTwoSided::FRONT, osg::StencilTwoSided::ALWAYS, 0, 0);
stencilWrite->setFunction(osg::StencilTwoSided::BACK, osg::StencilTwoSided::ALWAYS, 0, 0);
stencilWrite->setOperation(osg::StencilTwoSided::FRONT, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::DECR_WRAP, osg::StencilTwoSided::KEEP);
stencilWrite->setOperation(osg::StencilTwoSided::BACK, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::INCR_WRAP, osg::StencilTwoSided::KEEP);

stencilWrite->setWriteMask(osg::StencilTwoSided::FRONT, 0xFF);  //may not be needed
stencilWrite->setWriteMask(osg::StencilTwoSided::BACK, 0xFF);
stencilCamera->getOrCreateStateSet()->setAttribute(stencilWrite, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

stencilCamera->addChild(mtSphere);//lights.get());

osg::ref_ptr<osg::Program> stencilProg = new osg::Program;
stencilProg->addShader(osgDB::readShaderFile("nullTechnique.vert"));
stencilProg->addShader(osgDB::readShaderFile("nullTechnique.frag"));

stencilCamera->getOrCreateStateSet()->setAttributeAndModes(stencilProg.get(), osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

//3. pass: point light pass camera and set up
osg::ref_ptr<osg::Camera> pointLightCamera = createHUDCamera(0.0, 1.0, 0.0, 1.0);

pointLightCamera->setClearMask(0);
pointLightCamera->setRenderOrder(osg::Camera::POST_RENDER, 1);//PRE_RENDER, 2);
pointLightCamera->addChild(screenQuad);
ss = pointLightCamera->getOrCreateStateSet();

osg::ref_ptr<osg::Stencil> stencilRead = new osg::Stencil;
stencilRead->setFunction(osg::Stencil::NOTEQUAL, 1, 0xFF);  //render only where stencil buffer is != 0 (this will be 1 as set in stencil pass)
stencilRead->setWriteMask(0);//it should not write into the stencil buffer it reads from
ss->setAttribute(stencilRead, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);

osg::ref_ptr<osg::Depth> depthRead = new osg::Depth;
depth->setWriteMask(false);
ss->setAttribute(depth, osg::StateAttribute::ON);

pointLightCamera->attach(osg::Camera::PACKED_DEPTH_STENCIL_BUFFER, texDepth);
ss->setMode(GL_STENCIL_TEST, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
ss->setMode(GL_DEPTH_TEST, osg::StateAttribute::OFF);

ss->setMode(GL_BLEND, osg::StateAttribute::ON);         //all light passes shall add their renderings to the previous light passes
osg::ref_ptr<osg::BlendFunc> renderAddBlendFunc = new osg::BlendFunc;
renderAddBlendFunc->setFunction(GL_ONE, GL_ONE);
ss->setAttribute(renderAddBlendFunc, osg::StateAttribute::ON);
osg::ref_ptr<osg::BlendEquation> renderAddBlendEq = new osg::BlendEquation;
renderAddBlendEq->setEquation(osg::BlendEquation::FUNC_ADD);

ss->setAttribute(renderAddBlendEq, osg::StateAttribute::ON);
osg::ref_ptr<osg::CullFace> cullFacePointLightPass = new osg::CullFace(osg::CullFace::FRONT);

osg::ref_ptr<osg::Program> pointLightProg = new osg::Program;
vertShader = osgDB::readShaderFile("pass2.vert");
fragShader = osgDB::readShaderFile("pass2.frag");
pointLightProg->addShader(vertShader);
pointLightProg->addShader(fragShader);
ss->setAttributeAndModes(pointLightProg.get(), osg::StateAttribute::ON);
ss->setTextureAttributeAndModes(0, texColor);
ss->setTextureAttributeAndModes(1, texPosition);
ss->setTextureAttributeAndModes(2, texNormal);
ss->setTextureAttributeAndModes(3, texDepth);

ss->addUniform(new osg::Uniform("tDiffuse", 0));
ss->addUniform(new osg::Uniform("tPosition", 1));
ss->addUniform(new osg::Uniform("tNormals", 2));
ss->addUniform(new osg::Uniform("tDepth", 3));

ss->addUniform(new osg::Uniform("lightPosition", osg::Vec3(0.0, 0.0, 0.0)));

osg::Vec3 eye, center, up;
rttCamera->getViewMatrixAsLookAt(eye, center, up);
ss->addUniform(new osg::Uniform("cameraPosition", eye));

pointLightCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER);

osg::ref_ptr<osg::Group> root = new osg::Group;
root->addChild(rttCamera);
root->addChild(stencilCamera);
root->addChild(pointLightCamera);

osgViewer::Viewer viewer;
viewer.setCameraManipulator(new osgGA::TrackballManipulator);
viewer.getCamera()->setComputeNearFarMode(osg::CullSettings::DO_NOT_COMPUTE_NEAR_FAR);
viewer.setSceneData(root.get());

osg::DisplaySettings::instance()->setMinimumNumStencilBits(8);

（createRTTCamera和createHUDCamera正在从OSG Cookbook中获取）。

Answer 1

好的，我终于找到了问题。

我使用FRAME_BUFFER_OBJECT作为RTT摄像机的渲染目标实现，但是我的HUD摄像机使用FRAME_BUFFER。我后来注意到我得到了一个OpenGL“无效值”错误。现在我对所有三个使用FRAME_BUFFER_OBJECT，我可以共享模板值并且它可以工作。我只需要将我以前的HUD相机的结果写入一个新的纹理，然后我用最后一个相机读取，这是一个新的HUD相机，并且有FRAME_BUFFER作为渲染目标。

用于延迟着色的模板缓冲区，具有开放场景图

1 个答案: