OpenGL：三维平面坐标转化为二维

来源：互联网发布：淘宝会员等级在哪里看编辑：程序博客网时间：2024/05/10 06:15

相关联文章：openGL中视口变换矩阵求解

osg中世界坐标系到屏幕坐标系的变换

//返回三维点在二维屏幕上的投影点osg::Vec3d WorldToScreen(osgViewer::View* view,osg::Vec3 worldpoint){double in[4],out[4];in[0] = worldpoint._v[0];in[1] = worldpoint._v[1];in[2] = worldpoint._v[2];in[3] = 1.0;//获得当前的投影矩阵和模型视图矩阵osg::Matrix projectMatrix = view->getCamera()->getProjectionMatrix();osg::Matrix viewMatrix = view->getCamera()->getViewMatrix();//变换模型视图矩阵double modelViewMatrix[16];memcpy(modelViewMatrix,viewprojectMatrix.ptr(),sizeof(GLdouble)*16);Transform_Point(out,modelViewMatrix,in);//变换投影矩阵double myprojectMatrix[16];memcpy(myprojectMatrix,projectMatrix.ptr(),sizeof(GLdouble)*16);Transform_Point(out,myprojectMatrix,in);//变换视口变换矩阵if(in[3] == 0.0)  return osg::Vec3d(0,0,0);  in[0]/=in[3];in[1]/=in[3];in[2]/=in[3];int viewPort[4];osg::Viewport* myviewport = view->getCamera()->getViewport();viewPort[0] = myviewport->x();viewPort[1] = myviewport->y();viewPort[2] = myviewport->width();viewPort[3] = myviewport->height();//计算二维屏幕投影点osg::Vec3d screenPoint;screenPoint._v[0] = (int)(viewPort[0] + (1+in[0])*viewPort[2]/2+0.5);screenPoint._v[0] = (int)(viewPort[1] + (1+in[1])*viewPort[3]/2+0.5);screenPoint._v[2] = 0;return screenPoint;}

上面的程序只有最后计算二维屏幕投影点时，为啥要加上0.5，不懂！！

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