/// <summary>
/// 创建视图矩阵
/// 视图矩阵为右手坐标系，我们之前使用的都是左手坐标系
/// 所以需要先转成右手坐标系
/// </summary>
/// <param name="eyePos"></param>
/// <param name="nUp"></param>
/// <param name="lookAtPos"></param>
/// <returns></returns>
public static Matrix4x4 BuildViewMatrix(Vector4 eyePos, Vector4 nUp, Vector4 lookAtPos)
{
Vector4 forward = lookAtPos - eyePos;
forward.Normalize();
Vector4 side = Vector4.Corss(nUp, forward);
side.Normalize();
Vector4 up = Vector4.Corss(forward, side);
up.Normalize();
Matrix4x4 m1 = new Matrix4x4
(
1, 0, 0, -eyePos.x,
0, 1, 0, -eyePos.y,
0, 0, 1, -eyePos.z,
0, 0, 0, 1
);
Matrix4x4 m2 = new Matrix4x4
(
side.x, side.y, side.z, 0,
up.x, up.y, up.z, 0,
forward.x, forward.y, forward.z, 0,
0, 0, 0, 1
);
Matrix4x4 m3 = Matrix4x4.identityMatrix;
m3[2, 2] = -1;
return(m3 * m2 * m1);
}
