利用osg的双面模板缓冲技术实现剖切面填充问题
用下面这段代码，对多个封闭实体构成的模型 m_vecBufferNode，用一个矩形面m_vecSurFillGeom去切割模型，实现剖面的封闭。现在的问题是，剖面填充时，剖面范围是正确的的，但不能正确显示出每个剖面填充的颜色。图1-4是错误的剖面填充效果。想得到图5这样正确的填充效果（这是硬切出来的效果），请教各位，问题出在哪里？//更新剖面填充面
void s3dDynamicCut::UpdateFillSur(osg::ref_ptr<osg::Vec3Array>& clipSurfPnts, double clipParam)
{
int iTranNodeNum = m_vecBufferNode.size();
osg::ref_ptr<osg::ClipPlane> curClipPlane = new osg::ClipPlane;
curClipPlane->setClipPlane(clipParam, clipParam, clipParam, clipParam);
//清楚模板缓冲
if (m_sceneCamera != NULL)
{
unsigned int clearMask = m_sceneCamera->getClearMask();
m_sceneCamera->setClearMask(clearMask | GL_STENCIL_BUFFER_BIT);
m_sceneCamera->setClearStencil(0);
}
//模型绘制模板
osg::ref_ptr<osg::StencilTwoSided> cutBufferStencil1 = new osg::StencilTwoSided();
cutBufferStencil1->setFunction(StencilTwoSided::BACK, osg::StencilTwoSided::ALWAYS, 0, 0xFF);
cutBufferStencil1->setOperation(StencilTwoSided::BACK, osg::StencilTwoSided::INCR_WRAP, osg::StencilTwoSided::INCR_WRAP, osg::StencilTwoSided::INCR_WRAP);
cutBufferStencil1->setFunction(StencilTwoSided::FRONT, osg::StencilTwoSided::ALWAYS, 0, 0xFF);
cutBufferStencil1->setOperation(StencilTwoSided::FRONT, osg::StencilTwoSided::DECR_WRAP, osg::StencilTwoSided::DECR_WRAP, osg::StencilTwoSided::DECR_WRAP);
//剖面填充计算模板
osg::ref_ptr<osg::StencilTwoSided> cutBufferStencil2 = new osg::StencilTwoSided();
cutBufferStencil2->setFunction(osg::StencilTwoSided::BACK, osg::StencilTwoSided::NOTEQUAL, 0, 0xFF);
cutBufferStencil2->setOperation(StencilTwoSided::BACK, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::REPLACE);
cutBufferStencil2->setFunction(osg::StencilTwoSided::FRONT, osg::StencilTwoSided::NOTEQUAL, 0, 0xFF);
cutBufferStencil2->setOperation(StencilTwoSided::FRONT, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::KEEP, osg::StencilTwoSided::REPLACE);
//循环处理各个实体模型进行切割和剖面绘制
for (int i = 0; i < iTranNodeNum; i++)
{
//1.设置模型节点的裁剪面，切割模型，保留一边
m_vecBufferNode-->getOrCreateStateSet()->setAttributeAndModes(curClipPlane, osg::StateAttribute::ON);
m_vecBufferNode->getOrCreateStateSet()->setRenderBinDetails(-10, "RenderBin");
m_vecBufferNode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::OFF);
m_vecBufferNode->getOrCreateStateSet()->setAttribute(colorMaskTmp, osg::StateAttribute::ON);
//2. 先求出模型节点的模板缓冲(切面或盖子的地方为非0)
m_vecBufferNode->getOrCreateStateSet()->setAttributeAndModes(cutBufferStencil1, osg::StateAttribute::ON);
//3. 按照模型节点的颜色对剖面进行填充
m_vecSurFillGeom->setVertexArray(clipSurfPnts); //设置剖面几何边界
osgUtil::SmoothingVisitor::smooth(*m_vecSurFillGeom);//计算剖面法向
m_vecSurFillGeom->getOrCreateStateSet()->setAttributeAndModes(cutBufferStencil2, osg::StateAttribute::ON); //进行剖面填充
}
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