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//**************************************************
// Copyright©2018 何冠峰
// Licensed under the MIT license
//**************************************************
namespace UnityEngine
{
public struct Matrix3x3
{
public static readonly Matrix3x3 identity = new Matrix3x3(1, 0, 0, 0, 1, 0, 0, 0, 1);
public float[] Data;
public Matrix3x3(float m0, float m1, float m2, float m3, float m4, float m5, float m6, float m7, float m8)
{
Data = new float[9];
Data[0] = m0; Data[3] = m3; Data[6] = m6;
Data[1] = m1; Data[4] = m4; Data[7] = m7;
Data[2] = m2; Data[5] = m5; Data[8] = m8;
}
public void SetZero()
{
Data[0] = 0f; Data[3] = 0f; Data[6] = 0f;
Data[1] = 0f; Data[4] = 0f; Data[7] = 0f;
Data[2] = 0f; Data[5] = 0f; Data[8] = 0f;
//The floats are laid out
// m0 m3 m6
// m1 m4 m7
// m2 m5 m8
//Data[0]=m00; Data[3]=m01; Data[6]=m02;
//Data[1]=m10; Data[4]=m11; Data[7]=m12;
//Data[2]=m20; Data[5]=m21; Data[8]=m22;
//Get(0, 0) Get(0, 1) Get(0, 2)
//Get(1, 0) Get(1, 1) Get(1, 2)
//Get(2, 0) Get(2, 1) Get(2, 2)
}
public float Get(int row, int column)
{
return Data[row + (column * 3)];
}
public void Set(int row, int column, float value)
{
Data[row + (column * 3)] = value;
}
public void SetOrthoNormalBasis(Vector3 inX, Vector3 inY, Vector3 inZ)
{
this.Set(0, 0, inX.x); this.Set(0, 1, inY.x); this.Set(0, 2, inZ.x);
this.Set(1, 0, inX.y); this.Set(1, 1, inY.y); this.Set(1, 2, inZ.y);
this.Set(2, 0, inX.z); this.Set(2, 1, inY.z); this.Set(2, 2, inZ.z);
}
public float GetDeterminant()
{
float fCofactor0 = Get(0, 0) * Get(1, 1) * Get(2, 2);
float fCofactor1 = Get(0, 1) * Get(1, 2) * Get(2, 0);
float fCofactor2 = Get(0, 2) * Get(1, 0) * Get(2, 1);
float fCofactor3 = Get(0, 2) * Get(1, 1) * Get(2, 0);
float fCofactor4 = Get(0, 1) * Get(1, 0) * Get(2, 2);
float fCofactor5 = Get(0, 0) * Get(1, 2) * Get(2, 1);
return fCofactor0 + fCofactor1 + fCofactor2 - fCofactor3 - fCofactor4 - fCofactor5;
}
// Right handed
public static bool LookRotationToMatrix(Vector3 viewVec, Vector3 upVec, out Matrix3x3 m)
{
m = Matrix3x3.identity;
Vector3 z = viewVec;
// compute u0
float mag = z.Length();
if (mag < Mathf.Epsilon)
{
return false;
}
z /= mag;
Vector3 x = Vector3.Cross(upVec, z);
mag = x.Length();
if (mag < Mathf.Epsilon)
{
return false;
}
x /= mag;
Vector3 y = Vector3.Cross(z, x);
if (!Mathf.CompareApproximate(y.Length(), 1.0F))
return false;
m.SetOrthoNormalBasis(x, y, z);
return true;
}
}
}