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public/mathlib/vplane.h

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $Workfile:     $
+// $Date:         $
+// $NoKeywords: $
+//=============================================================================//
+
+#ifndef VPLANE_H
+#define VPLANE_H
+
+#ifdef _WIN32
+#pragma once
+#endif
+
+#include "mathlib/vector.h"
+
+typedef int SideType;
+
+// Used to represent sides of things like planes.
+#define	SIDE_FRONT	0
+#define	SIDE_BACK	1
+#define	SIDE_ON		2
+
+#define VP_EPSILON	0.01f
+
+
+class VPlane
+{
+public:
+				VPlane();
+				VPlane(const Vector &vNormal, vec_t dist);
+
+	void		Init(const Vector &vNormal, vec_t dist);
+
+	// Return the distance from the point to the plane.
+	vec_t		DistTo(const Vector &vVec) const;
+
+	// Copy.
+	VPlane&		operator=(const VPlane &thePlane);
+
+	// Returns SIDE_ON, SIDE_FRONT, or SIDE_BACK.
+	// The epsilon for SIDE_ON can be passed in.
+	SideType	GetPointSide(const Vector &vPoint, vec_t sideEpsilon=VP_EPSILON) const;
+
+	// Returns SIDE_FRONT or SIDE_BACK.
+	SideType	GetPointSideExact(const Vector &vPoint) const;
+
+	// Classify the box with respect to the plane.
+	// Returns SIDE_ON, SIDE_FRONT, or SIDE_BACK
+	SideType	BoxOnPlaneSide(const Vector &vMin, const Vector &vMax) const;
+
+#ifndef VECTOR_NO_SLOW_OPERATIONS
+	// Flip the plane.
+	VPlane		Flip();
+
+	// Get a point on the plane (normal*dist).
+	Vector		GetPointOnPlane() const;
+
+	// Snap the specified point to the plane (along the plane's normal).
+	Vector		SnapPointToPlane(const Vector &vPoint) const;
+#endif
+
+public:
+	Vector		m_Normal;
+	vec_t		m_Dist;
+
+#ifdef VECTOR_NO_SLOW_OPERATIONS
+private:
+	// No copy constructors allowed if we're in optimal mode
+	VPlane(const VPlane& vOther);
+#endif
+};
+
+
+//-----------------------------------------------------------------------------
+// Inlines.
+//-----------------------------------------------------------------------------
+inline VPlane::VPlane()
+{
+}
+
+inline VPlane::VPlane(const Vector &vNormal, vec_t dist)
+{
+	m_Normal = vNormal;
+	m_Dist = dist;
+}
+
+inline void	VPlane::Init(const Vector &vNormal, vec_t dist)
+{
+	m_Normal = vNormal;
+	m_Dist = dist;
+}
+
+inline vec_t VPlane::DistTo(const Vector &vVec) const
+{
+	return vVec.Dot(m_Normal) - m_Dist;
+}
+
+inline VPlane& VPlane::operator=(const VPlane &thePlane)
+{
+	m_Normal = thePlane.m_Normal;
+	m_Dist = thePlane.m_Dist;
+	return *this;
+}
+
+#ifndef VECTOR_NO_SLOW_OPERATIONS
+
+inline VPlane VPlane::Flip()
+{
+	return VPlane(-m_Normal, -m_Dist);
+}
+
+inline Vector VPlane::GetPointOnPlane() const
+{
+	return m_Normal * m_Dist;
+}
+
+inline Vector VPlane::SnapPointToPlane(const Vector &vPoint) const
+{
+	return vPoint - m_Normal * DistTo(vPoint);
+}
+
+#endif
+
+inline SideType VPlane::GetPointSide(const Vector &vPoint, vec_t sideEpsilon) const
+{
+	vec_t fDist;
+
+	fDist = DistTo(vPoint);
+	if(fDist >= sideEpsilon)
+		return SIDE_FRONT;
+	else if(fDist <= -sideEpsilon)
+		return SIDE_BACK;
+	else
+		return SIDE_ON;
+}
+
+inline SideType VPlane::GetPointSideExact(const Vector &vPoint) const
+{
+	return DistTo(vPoint) > 0.0f ? SIDE_FRONT : SIDE_BACK;
+}
+
+
+// BUGBUG: This should either simply use the implementation in mathlib or cease to exist.
+// mathlib implementation is much more efficient.  Check to see that VPlane isn't used in
+// performance critical code.
+inline SideType VPlane::BoxOnPlaneSide(const Vector &vMin, const Vector &vMax) const
+{
+	int i, firstSide, side;
+	TableVector vPoints[8] = 
+	{
+		{ vMin.x, vMin.y, vMin.z },
+		{ vMin.x, vMin.y, vMax.z },
+		{ vMin.x, vMax.y, vMax.z },
+		{ vMin.x, vMax.y, vMin.z },
+
+		{ vMax.x, vMin.y, vMin.z },
+		{ vMax.x, vMin.y, vMax.z },
+		{ vMax.x, vMax.y, vMax.z },
+		{ vMax.x, vMax.y, vMin.z },
+	};
+
+	firstSide = GetPointSideExact(vPoints[0]);
+	for(i=1; i < 8; i++)
+	{
+		side = GetPointSideExact(vPoints[i]);
+
+		// Does the box cross the plane?
+		if(side != firstSide)
+			return SIDE_ON;
+	}
+
+	// Ok, they're all on the same side, return that.
+	return firstSide;
+}
+
+
+
+
+#endif // VPLANE_H