用到了glReadPixels glDrawPixels glCopyPixels来创建和拷贝位图-uses glReadPixels glDrawPixels glCopyPix els to create and copy bitmap

用到了glReadPixels glDrawPixels glCopyPixels来创建和拷贝位图-uses glReadPixels glDrawPixels glCopyPix els to create and copy bitmap

用opengl自带的glReadPixels(以及gluUnProject(）函数和点落在三角形内的矢量判断IntersectTriangle然后转成三维坐标的两种方式获取屏幕点选的场景坐标，通过对比发现其值是一样。-Use opengl own glReadPixels (as well as gluUnProject () function and the points fall within the vector triangle

The only special thing we need to do for the state tracker s glReadPixels is to validate state (to be sure we have up-to-date fr a mebuffer surfaces) and flush the bitmap cache prior to reading.