test/Assets/PerfectWorld/Scripts/Managers/HalfSpace.cs

using CSNetwork.GPDataType;
using System;
using UnityEngine;
using UnityEngine.UIElements;

namespace BrewMonster.Scripts
{
    public class CHalfSpace
    {
        public static float DistThresh;        //空间一顶点到halfspace平面的距离阈值，作为判断是在半空间内部、外部，or 边界上
                                               //该阈值属于整个类而不是某一个对象，因此定义为静态成员
                                               //根据三个顶点构造平面及半空间区域
                                               //Attributes
        public const float HS_DEFAULT_DISTTHRESH = 0.000001f;				//距离差的阈值，作为判断是在半空间内部or边界上

        protected A3DVECTOR3 m_vNormal;
        protected float m_d;

        public void Set(A3DVECTOR3 v1, A3DVECTOR3 v2)
        {
            m_vNormal = A3DVECTOR3.CrossProduct(v2 - v1, new A3DVECTOR3(0.0f, 0.0f, 1.0f));
            m_vNormal.Normalize();
            m_d = A3DVECTOR3.DotProduct(v1, m_vNormal);
        }
        public void Set(A3DVECTOR3 v1, A3DVECTOR3 v2, A3DVECTOR3 v3)
        {
            m_vNormal = A3DVECTOR3.CrossProduct(v2 - v1, v3 - v1);
            m_vNormal.Normalize();
            m_d = A3DVECTOR3.DotProduct(v1, m_vNormal);
        }

        //直接设置法向
        public void SetNormal(A3DVECTOR3 n) { m_vNormal = n; m_vNormal.Normalize(); }

        public float GetDist() { return m_d; }

        //直接设置距离d
        public void SetD(float d) { m_d = d; }

        public CHalfSpace(A3DVECTOR3 v1, A3DVECTOR3 v2, A3DVECTOR3 v3)
        {
            Set(v1, v2, v3);

        }
        //根据两个顶点构造平行于Z轴的平面及半空间区域
        public CHalfSpace(A3DVECTOR3 v1, A3DVECTOR3 v2)
        {
            Set(v1, v2);
        }
        public CHalfSpace()
        {

        }

        public CHalfSpace(CHalfSpace hs)
        {
            m_vNormal = hs.m_vNormal;
            m_d = hs.m_d;
        }

        // 对决定Halfspace的平面进行变换！变换矩阵为mtxTrans
        public virtual void Transform(A3DMATRIX4 mtxTrans)
        {
            //从mtxTrans分解出Scale,Rotate,Translate分量
            A3DVECTOR3 vTranslate = mtxTrans.GetRow(3);
            float fScale = mtxTrans.GetCol(0).Magnitude();

            // 与mtxTrans一样，仍定义为右乘矩阵
            A3DMATRIX3 mtx3Rotate = new A3DMATRIX3();
            mtx3Rotate.m = new float[3 * 3];
            for (int i = 0; i < 3; i++)
                for (int j = 0; j < 3; j++)
                    mtx3Rotate.m[(i * 3) + j] = mtxTrans.m[(i * 4) + j] / fScale;

            //对于平面方程N.X=D的变换(s,R,t)如下：

            // N'=NR
            SetNormal(m_vNormal * mtx3Rotate);

            //D'=s*D+N'.t
            SetD(fScale * m_d + A3DVECTOR3.DotProduct(m_vNormal, vTranslate));
        }

        public void Translate(float Delta) { m_d += Delta; }               //沿法线方向作一个平移
        public void Inverse() { m_d = -m_d; m_vNormal = -m_vNormal; }      //翻转半空间的正反方向

        //点v到半空间定义平面的距离，此距离带符号！
        public float DistV2Plane(A3DVECTOR3 v)
        {
            float d = A3DVECTOR3.DotProduct(v, m_vNormal);
            return (d - m_d);
        }

        //与线段求交
        public int IntersectLineSeg(A3DVECTOR3 v1, A3DVECTOR3 v2, A3DVECTOR3 vIntersection)
        {
            vIntersection = new A3DVECTOR3(0.0f, 0.0f, 0.0f);
            //先处理在平面上的情况
            bool v1InPlane = OnPlane(v1);
            bool v2InPlane = OnPlane(v2);
            if (v1InPlane && v2InPlane) return 3;
            if (v1InPlane) return 1;
            if (v2InPlane) return 2;

            if (Outside(v1) ^ Outside(v2))
            {
                //两顶点分别在两侧，计算交点
                A3DVECTOR3 vd = v2 - v1;
                float t = m_d - A3DVECTOR3.DotProduct(m_vNormal, v1);
                t /= A3DVECTOR3.DotProduct(m_vNormal, vd);
                //assert(t < 1.0f && t > 0.0f);
                vIntersection = v1 + t * vd;

                return 4;
            }
            else
                return 0;
        }

        ////////////////////////////////////////////////////////////
        // 判断一个三维点是否处于半空间内部，或者说处于平面的一侧
        // 注意halfspace的OutSide,Inside定义方式
        //				   /\
        //		          /||\
        //				   ||
        //				   || normal    (Outside)
        //------------------------------------------Plane
        //								(Inside)
        //
        public bool Inside(A3DVECTOR3 v)
        {
            float d = A3DVECTOR3.DotProduct(v, m_vNormal);
            bool bInside = (m_d - d > DistThresh);
            return (bInside);
        }
        public bool Outside(A3DVECTOR3 v)
        {
            float d = A3DVECTOR3.DotProduct(v, m_vNormal);
            bool bOutside = (d - m_d > DistThresh);
            return (bOutside);
        }
        public bool OnPlane(A3DVECTOR3 v)
        {
            float d = A3DVECTOR3.DotProduct(v, m_vNormal);
            bool bOnPlane = (Math.Abs(m_d - d) <= DistThresh);
            return bOnPlane;
        }

        //set && get operations
        public static void SetDistThresh(float DThresh = HS_DEFAULT_DISTTHRESH)        //并设定一个缺省值
        {
            DistThresh = DThresh;
        }

        public A3DVECTOR3 GetNormal() { return m_vNormal; }

        //点法式
        public void SetNV(A3DVECTOR3 n, A3DVECTOR3 v)
        {
            m_vNormal = n;
            m_vNormal.Normalize();
            m_d = A3DVECTOR3.DotProduct(m_vNormal, v);
        }

    }
}