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Clipping volumes

by Brett Fattori · in Torque Game Engine · 02/23/2004 (8:59 am) · 1 replies

Was looking at some code in the engine in SceneState.cc in the "isObjectRendered()" method. It seems to generate a clipping volume that originates at the near plane and extends to the far plane (or fogging distance, can't remember exactly). Then, with a little searching, I found some code in fxFoliageReplicator that does something similar to create a view volume to determine if a quadrant should show or not. It's nicely commmented, but I'm still kinda baffled.

Well, I need something similar, but not exactly like it.. :-)

I need a volume that originates at a light's position (let's call it lightPos) and stretches to the near plane. Thus, I would have a view volume for what the light can see. I need this to determine which objects clip a light for determining if a shadow becomes z-fail. I've been having a hell of a time with this, so any help would be appreciated.

Thanks,

- Brett
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Associate Matt Fairfax
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#1
02/23/2004 (9:41 am)
Maybe do something like this from Player::step()

ClippedPolyList polyList;
polyList.mPlaneList.clear();
polyList.mNormal.set(0,0,0);
polyList.mPlaneList.setSize(6);
polyList.mPlaneList[0].set(box.min,VectorF(-1,0,0));
polyList.mPlaneList[1].set(box.max,VectorF(0,1,0));
polyList.mPlaneList[2].set(box.max,VectorF(1,0,0));
polyList.mPlaneList[3].set(box.min,VectorF(0,-1,0));
polyList.mPlaneList[4].set(box.min,VectorF(0,0,-1));
polyList.mPlaneList[5].set(box.max,VectorF(0,0,1));

CollisionWorkingList& rList = mConvex.getWorkingList();
CollisionWorkingList* pList = rList.wLink.mNext;
while (pList != &rList) {
   Convex* pConvex = pList->mConvex;
   if ((pConvex->getObject()->getType() & StaticObjectType) != 0)
   {
      Box3F convexBox = pConvex->getBoundingBox();
      if (box.isOverlapped(convexBox))
      {
         // The object is partially inside the volume
         pConvex->getPolyList(&polyList);
      }
   }
   pList = pList->wLink.mNext;
}