Torque3D/Engine/lib/opcode/OPC_BoxBoxOverlap.h

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
 *	OBB-OBB overlap test using the separating axis theorem.
 *	- original code by Gomez / Gamasutra (similar to Gottschalk's one in RAPID)
 *	- optimized for AABB trees by computing the rotation matrix once (SOLID-fashion)
 *	- the fabs matrix is precomputed as well and epsilon-tweaked (RAPID-style, we found this almost mandatory)
 *	- Class III axes can be disabled... (SOLID & Intel fashion)
 *	- ...or enabled to perform some profiling
 *	- CPU comparisons used when appropriate
 *	- lazy evaluation sometimes saves some work in case of early exits (unlike SOLID)
 *
 *	\param		ea	[in] extents from box A
 *	\param		ca	[in] center from box A
 *	\param		eb	[in] extents from box B
 *	\param		cb	[in] center from box B
 *	\return		true if boxes overlap
 */
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
inline_ BOOL AABBTreeCollider::BoxBoxOverlap(const Point& ea, const Point& ca, const Point& eb, const Point& cb)
{
	// Stats
	mNbBVBVTests++;

	float t,t2;

	// Class I : A's basis vectors
	float Tx = (mR1to0.m[0][0]*cb.x + mR1to0.m[1][0]*cb.y + mR1to0.m[2][0]*cb.z) + mT1to0.x - ca.x;
	t = ea.x + eb.x*mAR.m[0][0] + eb.y*mAR.m[1][0] + eb.z*mAR.m[2][0];
	if(GREATER(Tx, t))	return FALSE;

	float Ty = (mR1to0.m[0][1]*cb.x + mR1to0.m[1][1]*cb.y + mR1to0.m[2][1]*cb.z) + mT1to0.y - ca.y;
	t = ea.y + eb.x*mAR.m[0][1] + eb.y*mAR.m[1][1] + eb.z*mAR.m[2][1];
	if(GREATER(Ty, t))	return FALSE;

	float Tz = (mR1to0.m[0][2]*cb.x + mR1to0.m[1][2]*cb.y + mR1to0.m[2][2]*cb.z) + mT1to0.z - ca.z;
	t = ea.z + eb.x*mAR.m[0][2] + eb.y*mAR.m[1][2] + eb.z*mAR.m[2][2];
	if(GREATER(Tz, t))	return FALSE;

	// Class II : B's basis vectors
	t = Tx*mR1to0.m[0][0] + Ty*mR1to0.m[0][1] + Tz*mR1to0.m[0][2];	t2 = ea.x*mAR.m[0][0] + ea.y*mAR.m[0][1] + ea.z*mAR.m[0][2] + eb.x;
	if(GREATER(t, t2))	return FALSE;

	t = Tx*mR1to0.m[1][0] + Ty*mR1to0.m[1][1] + Tz*mR1to0.m[1][2];	t2 = ea.x*mAR.m[1][0] + ea.y*mAR.m[1][1] + ea.z*mAR.m[1][2] + eb.y;
	if(GREATER(t, t2))	return FALSE;

	t = Tx*mR1to0.m[2][0] + Ty*mR1to0.m[2][1] + Tz*mR1to0.m[2][2];	t2 = ea.x*mAR.m[2][0] + ea.y*mAR.m[2][1] + ea.z*mAR.m[2][2] + eb.z;
	if(GREATER(t, t2))	return FALSE;

	// Class III : 9 cross products
	// Cool trick: always perform the full test for first level, regardless of settings.
	// That way pathological cases (such as the pencils scene) are quickly rejected anyway !
	if(mFullBoxBoxTest || mNbBVBVTests==1)
	{
		t = Tz*mR1to0.m[0][1] - Ty*mR1to0.m[0][2];	t2 = ea.y*mAR.m[0][2] + ea.z*mAR.m[0][1] + eb.y*mAR.m[2][0] + eb.z*mAR.m[1][0];	if(GREATER(t, t2))	return FALSE;	// L = A0 x B0
		t = Tz*mR1to0.m[1][1] - Ty*mR1to0.m[1][2];	t2 = ea.y*mAR.m[1][2] + ea.z*mAR.m[1][1] + eb.x*mAR.m[2][0] + eb.z*mAR.m[0][0];	if(GREATER(t, t2))	return FALSE;	// L = A0 x B1
		t = Tz*mR1to0.m[2][1] - Ty*mR1to0.m[2][2];	t2 = ea.y*mAR.m[2][2] + ea.z*mAR.m[2][1] + eb.x*mAR.m[1][0] + eb.y*mAR.m[0][0];	if(GREATER(t, t2))	return FALSE;	// L = A0 x B2
		t = Tx*mR1to0.m[0][2] - Tz*mR1to0.m[0][0];	t2 = ea.x*mAR.m[0][2] + ea.z*mAR.m[0][0] + eb.y*mAR.m[2][1] + eb.z*mAR.m[1][1];	if(GREATER(t, t2))	return FALSE;	// L = A1 x B0
		t = Tx*mR1to0.m[1][2] - Tz*mR1to0.m[1][0];	t2 = ea.x*mAR.m[1][2] + ea.z*mAR.m[1][0] + eb.x*mAR.m[2][1] + eb.z*mAR.m[0][1];	if(GREATER(t, t2))	return FALSE;	// L = A1 x B1
		t = Tx*mR1to0.m[2][2] - Tz*mR1to0.m[2][0];	t2 = ea.x*mAR.m[2][2] + ea.z*mAR.m[2][0] + eb.x*mAR.m[1][1] + eb.y*mAR.m[0][1];	if(GREATER(t, t2))	return FALSE;	// L = A1 x B2
		t = Ty*mR1to0.m[0][0] - Tx*mR1to0.m[0][1];	t2 = ea.x*mAR.m[0][1] + ea.y*mAR.m[0][0] + eb.y*mAR.m[2][2] + eb.z*mAR.m[1][2];	if(GREATER(t, t2))	return FALSE;	// L = A2 x B0
		t = Ty*mR1to0.m[1][0] - Tx*mR1to0.m[1][1];	t2 = ea.x*mAR.m[1][1] + ea.y*mAR.m[1][0] + eb.x*mAR.m[2][2] + eb.z*mAR.m[0][2];	if(GREATER(t, t2))	return FALSE;	// L = A2 x B1
		t = Ty*mR1to0.m[2][0] - Tx*mR1to0.m[2][1];	t2 = ea.x*mAR.m[2][1] + ea.y*mAR.m[2][0] + eb.x*mAR.m[1][2] + eb.y*mAR.m[0][2];	if(GREATER(t, t2))	return FALSE;	// L = A2 x B2
	}
	return TRUE;
}

//! A dedicated version when one box is constant
inline_ BOOL OBBCollider::BoxBoxOverlap(const Point& extents, const Point& center)
{
	// Stats
	mNbVolumeBVTests++;

	float t,t2;

	// Class I : A's basis vectors
	float Tx = mTBoxToModel.x - center.x;	t = extents.x + mBBx1;	if(GREATER(Tx, t))	return FALSE;
	float Ty = mTBoxToModel.y - center.y;	t = extents.y + mBBy1;	if(GREATER(Ty, t))	return FALSE;
	float Tz = mTBoxToModel.z - center.z;	t = extents.z + mBBz1;	if(GREATER(Tz, t))	return FALSE;

	// Class II : B's basis vectors
	t = Tx*mRBoxToModel.m[0][0] + Ty*mRBoxToModel.m[0][1] + Tz*mRBoxToModel.m[0][2];
	t2 = extents.x*mAR.m[0][0] + extents.y*mAR.m[0][1] + extents.z*mAR.m[0][2] + mBoxExtents.x;
	if(GREATER(t, t2))	return FALSE;

	t = Tx*mRBoxToModel.m[1][0] + Ty*mRBoxToModel.m[1][1] + Tz*mRBoxToModel.m[1][2];
	t2 = extents.x*mAR.m[1][0] + extents.y*mAR.m[1][1] + extents.z*mAR.m[1][2] + mBoxExtents.y;
	if(GREATER(t, t2))	return FALSE;

	t = Tx*mRBoxToModel.m[2][0] + Ty*mRBoxToModel.m[2][1] + Tz*mRBoxToModel.m[2][2];
	t2 = extents.x*mAR.m[2][0] + extents.y*mAR.m[2][1] + extents.z*mAR.m[2][2] + mBoxExtents.z;
	if(GREATER(t, t2))	return FALSE;

	// Class III : 9 cross products
	// Cool trick: always perform the full test for first level, regardless of settings.
	// That way pathological cases (such as the pencils scene) are quickly rejected anyway !
	if(mFullBoxBoxTest || mNbVolumeBVTests==1)
	{
		t = Tz*mRBoxToModel.m[0][1] - Ty*mRBoxToModel.m[0][2];	t2 = extents.y*mAR.m[0][2] + extents.z*mAR.m[0][1] + mBB_1;	if(GREATER(t, t2))	return FALSE;	// L = A0 x B0
		t = Tz*mRBoxToModel.m[1][1] - Ty*mRBoxToModel.m[1][2];	t2 = extents.y*mAR.m[1][2] + extents.z*mAR.m[1][1] + mBB_2;	if(GREATER(t, t2))	return FALSE;	// L = A0 x B1
		t = Tz*mRBoxToModel.m[2][1] - Ty*mRBoxToModel.m[2][2];	t2 = extents.y*mAR.m[2][2] + extents.z*mAR.m[2][1] + mBB_3;	if(GREATER(t, t2))	return FALSE;	// L = A0 x B2
		t = Tx*mRBoxToModel.m[0][2] - Tz*mRBoxToModel.m[0][0];	t2 = extents.x*mAR.m[0][2] + extents.z*mAR.m[0][0] + mBB_4;	if(GREATER(t, t2))	return FALSE;	// L = A1 x B0
		t = Tx*mRBoxToModel.m[1][2] - Tz*mRBoxToModel.m[1][0];	t2 = extents.x*mAR.m[1][2] + extents.z*mAR.m[1][0] + mBB_5;	if(GREATER(t, t2))	return FALSE;	// L = A1 x B1
		t = Tx*mRBoxToModel.m[2][2] - Tz*mRBoxToModel.m[2][0];	t2 = extents.x*mAR.m[2][2] + extents.z*mAR.m[2][0] + mBB_6;	if(GREATER(t, t2))	return FALSE;	// L = A1 x B2
		t = Ty*mRBoxToModel.m[0][0] - Tx*mRBoxToModel.m[0][1];	t2 = extents.x*mAR.m[0][1] + extents.y*mAR.m[0][0] + mBB_7;	if(GREATER(t, t2))	return FALSE;	// L = A2 x B0
		t = Ty*mRBoxToModel.m[1][0] - Tx*mRBoxToModel.m[1][1];	t2 = extents.x*mAR.m[1][1] + extents.y*mAR.m[1][0] + mBB_8;	if(GREATER(t, t2))	return FALSE;	// L = A2 x B1
		t = Ty*mRBoxToModel.m[2][0] - Tx*mRBoxToModel.m[2][1];	t2 = extents.x*mAR.m[2][1] + extents.y*mAR.m[2][0] + mBB_9;	if(GREATER(t, t2))	return FALSE;	// L = A2 x B2
	}
	return TRUE;
}

//! A special version for 2 axis-aligned boxes
inline_ BOOL AABBCollider::AABBAABBOverlap(const Point& extents, const Point& center)
{
	// Stats
	mNbVolumeBVTests++;

	float tx = mBox.mCenter.x - center.x;	float ex = extents.x + mBox.mExtents.x;	if(GREATER(tx, ex))	return FALSE;
	float ty = mBox.mCenter.y - center.y;	float ey = extents.y + mBox.mExtents.y;	if(GREATER(ty, ey))	return FALSE;
	float tz = mBox.mCenter.z - center.z;	float ez = extents.z + mBox.mExtents.z;	if(GREATER(tz, ez))	return FALSE;

	return TRUE;
}