Constraining camera to terrain / interiors

This code stops the camera in observer mode from entering interiors and the terrain by maintaining a fixed distance from the terrain and walls. As the camera collides with the terrain / walls, it 'skims' along the surface, continuing to move in the directions that it can move - just not in the direction where the collision occurs.

Note: if the camera moves too quickly this code does not catch the collisions. I'm hoping someone can help me figure out why. Also - I have only tested this on windows, and only with the 1.1.2 revision.

In camera.h, add this function:

Point3F updatePos(const Point3F& oldPos,const Point3F& newPos, F32 testLen);

In camera.cc, add the implementation:

Point3F Camera::updatePos(const Point3F& oldPos,const Point3F& newPos, F32 testLen)
{
	if (oldPos==newPos || gEditingMission)
		return newPos;
	
	Point3F test=newPos-oldPos;
	F32 len = test.len();
	test.normalize();
	Point3F testPos = oldPos+(test*(len+testLen));
	
	RayInfo rinfo;

	if (getContainer()!=NULL) {
		if (getContainer()->castRay(oldPos, testPos, (InteriorObjectType | TerrainObjectType), &rinfo)) {
			float dot = mDot(test,rinfo.normal);
			if (dot < 0) {
				// Get a vector for the direction and distance the test point overshot
				Point3F oops = testPos - rinfo.point;
				// Get the length we shot past
				F32 newLen = mDot(oops,rinfo.normal);
				if (newLen > testLen)
					newLen=testLen;
				
				// Subtract the vector that took us past the collision point
				return (newPos - newLen*rinfo.normal);
			} else
				return newPos;
		}
		else {
			return newPos;
		}
	} else {
		return newPos;
	}   
}

In processTick(), right before the setPosition when not in orbit mode,
add a call to updatePos.

...

if(mode == OrbitObjectMode || mode == OrbitPointMode)
      {
         if(mode == OrbitObjectMode && bool(mOrbitObject))
            mOrbitObject->getWorldBox().getCenter(&mPosition);
         setPosition(mPosition, mRot);
         validateEyePoint(1.0f, &mObjToWorld);
         pos = mPosition;
      }
      else
      {
         // Update pos
         bool faster = move->trigger[0] || move->trigger[1];
         F32 scale = mMovementSpeed * (faster + 1);

         mObjToWorld.getColumn(3,&pos);
         mObjToWorld.getColumn(0,&vec);
         pos += vec * move->x * TickSec * scale;
         mObjToWorld.getColumn(1,&vec);
         pos += vec * move->y * TickSec * scale;
         mObjToWorld.getColumn(2,&vec);
         pos += vec * move->z * TickSec * scale;
		 
	 pos = updatePos(getTransform().getPosition(),pos,5.0); // <- added call

         setPosition(pos,mRot);
      }

Also added the same call in interpolateTick:

void Camera::interpolateTick(F32 dt)          
{
   Parent::interpolateTick(dt);
   Point3F rot = delta.rot + delta.rotVec * dt;

   if(mode == OrbitObjectMode || mode == OrbitPointMode)
   {
      if(mode == OrbitObjectMode && bool(mOrbitObject))
         mOrbitObject->getRenderWorldBox().getCenter(&mPosition);
      setPosition(mPosition, rot);
      validateEyePoint(1.0f, &mObjToWorld);
   }
   else {
      Point3F pos = delta.pos + delta.posVec * dt;
      pos = updatePos(getTransform().getPosition(),pos,5.0); // <-- added call
      setPosition(pos,rot);
   }
}