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thirdparty/ode-0.16.5/OPCODE/OPC_RayTriOverlap.h

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+#define LOCAL_EPSILON 0.000001f
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+/**
+ *	Computes a ray-triangle intersection test.
+ *	Original code from Tomas M<>ller's "Fast Minimum Storage Ray-Triangle Intersection".
+ *	It's been optimized a bit with integer code, and modified to return a non-intersection if distance from
+ *	ray origin to triangle is negative.
+ *
+ *	\param		vert0	[in] triangle vertex
+ *	\param		vert1	[in] triangle vertex
+ *	\param		vert2	[in] triangle vertex
+ *	\return		true on overlap. mStabbedFace is filled with relevant info.
+ */
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+inline_ BOOL RayCollider::RayTriOverlap(const Point& vert0, const Point& vert1, const Point& vert2)
+{
+	// Stats
+	mNbRayPrimTests++;
+
+	// Find vectors for two edges sharing vert0
+	Point edge1 = vert1 - vert0;
+	Point edge2 = vert2 - vert0;
+
+	// Begin calculating determinant - also used to calculate U parameter
+	Point pvec = mDir^edge2;
+
+	// If determinant is near zero, ray lies in plane of triangle
+	float det = edge1|pvec;
+
+	if(mCulling)
+	{
+		if(det <= LOCAL_EPSILON * FCMin2(edge1.SquareMagnitude(), edge2.SquareMagnitude())) return FALSE;
+		// From here, det is > 0. So we can use integer cmp.
+
+		// Calculate distance from vert0 to ray origin
+		Point tvec = mOrigin - vert0;
+
+		// Calculate U parameter and test bounds
+		mStabbedFace.mU = tvec|pvec;
+//		if(IR(u)&0x80000000 || u>det)					return FALSE;
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IR(det))		return FALSE;
+
+		// Prepare to test V parameter
+		Point qvec = tvec^edge1;
+
+		// Calculate V parameter and test bounds
+		mStabbedFace.mV = mDir|qvec;
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>det)	return FALSE;
+
+		// Calculate t, scale parameters, ray intersects triangle
+		mStabbedFace.mDistance = edge2|qvec;
+		// Det > 0 so we can early exit here
+		// Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance))								return FALSE;
+		// Else go on
+		float OneOverDet = 1.0f / det;
+		mStabbedFace.mDistance *= OneOverDet;
+		mStabbedFace.mU *= OneOverDet;
+		mStabbedFace.mV *= OneOverDet;
+	}
+	else
+	{
+		// the non-culling branch
+		if(FastFabs(det) <= LOCAL_EPSILON * FCMin2(edge1.SquareMagnitude(), edge2.SquareMagnitude())) return FALSE;
+		float OneOverDet = 1.0f / det;
+
+		// Calculate distance from vert0 to ray origin
+		Point tvec = mOrigin - vert0;
+
+		// Calculate U parameter and test bounds
+		mStabbedFace.mU = (tvec|pvec) * OneOverDet;
+//		if(IR(u)&0x80000000 || u>1.0f)					return FALSE;
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IEEE_1_0)		return FALSE;
+
+		// prepare to test V parameter
+		Point qvec = tvec^edge1;
+
+		// Calculate V parameter and test bounds
+		mStabbedFace.mV = (mDir|qvec) * OneOverDet;
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>1.0f)	return FALSE;
+
+		// Calculate t, ray intersects triangle
+		mStabbedFace.mDistance = (edge2|qvec) * OneOverDet;
+		// Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
+		if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance))								return FALSE;
+	}
+	return TRUE;
+}