   Unit Cube Clipping for LisPSM
  Hi.I'm reading about LisPSM and got some codefrom nvidia.comWhen apply unit cube clipping for LisPSMthe shadow quality is much better then before.But I don't know what the code means.I mean what the unit cube clipping means for LisPSMand how to apply it for LisPSM.There are other tech such as PSM,TSM.But this time I want to focus on LisPSM first.Thanks.
  I believe their unit cube clipping applies to PSM specifically.At least this is the case if you are talking about the algorithmin GPU Gems 1.;  imagine the light's povnow instead of rendering from the light's pov (looking down z)you use a lookat vector which is perpendicular to the light z vectorbut with direction as close as possible to the view z vectorthen after you calculate:Pproj = mul(Pview, MworldViewProj)you just swizzle it aroundPproj = Pproj.xzy; // for exampleso you end up with linear z and non-linear x axis;Hi.I'm reading about LisPSM and got some codefrom nvidia.comWhen apply unit cube clipping for LisPSMthe shadow quality is much better then before.But I don't know what the code means.I mean what the unit cube clipping means for LisPSMand how to apply it for LisPSM.There are other tech such as PSM,TSM.But this time I want to focus on LisPSM first.Thanks.I think you will find that the y divide for this technique seriously damages the z precision of the shadowmap, and you will still be left dealing with the dueling frusta cases unless you have a locked POV (say an isometric camera for an RTS style game).   