Question

我现在已经陷入了几个小时的问题。我需要将我的4x4矩阵（模型，视图，投影）转换为带有平移向量的3x3矩阵。我需要这样做，因为我使用的API没有4x4矩阵类和完全封闭的源。

奇怪的是，他们的LookAt函数声明它根本不会影响矩阵的平移部分。我用于渲染的4x4矩阵的位置（Everything渲染100％正确）。

有人可以看看我的转换功能，看看我做错了什么？感谢

CIwFMat ConvertToMarmaladeFormat(Matrix4& Mat)
{
    CIwFMat M;

    M.m[0][0] = Mat[0][0];
    M.m[0][1] = Mat[0][1];
    M.m[0][2] = Mat[0][2];

    M.m[1][0] = Mat[1][0];
    M.m[1][1] = Mat[1][1];
    M.m[1][2] = Mat[1][2];

    M.m[2][0] = Mat[2][0];
    M.m[2][1] = Mat[2][1];
    M.m[2][2] = Mat[2][2];

    M.t = CIwFVec3(Mat[3][0], Mat[3][1], Mat[3][2]);

    return M;
}

Matrix4 ConvertFromMarmaladeFormat(CIwFMat& M)
{
    Matrix4 Mat;
    Mat.identity();

    Mat[0][0] = M.m[0][0];
    Mat[0][1] = M.m[0][1];
    Mat[0][2] = M.m[0][2];

    Mat[1][0] = M.m[1][0];
    Mat[1][1] = M.m[1][1];
    Mat[1][2] = M.m[1][2];

    Mat[2][0] = M.m[2][0];
    Mat[2][1] = M.m[2][1];
    Mat[2][2] = M.m[2][2];

    Mat[3][0] = M.t.x;
    Mat[3][1] = M.t.y;
    Mat[3][2] = M.t.z;

    return Mat;
}

class Matrix4
{
    friend Vector4 operator*(const Vector4 &lhs, const Matrix4 &rhs);
    friend Vector3 operator*(const Vector3 &lhs, const Matrix4 &rhs);
    friend Matrix4 operator*(float scalar, const Matrix4 &rhs);

public:
    static const Matrix4 IDENTITY;
    static Matrix4 createFromAxes(const Vector3 &x, const Vector3 &y, const Vector3 &z);
    static Matrix4 createFromAxesTransposed(const Vector3 &x, const Vector3 &y, const Vector3 &z);
    static Matrix4 createFromHeadPitchRoll(float headDegrees, float pitchDegrees, float rollDegrees);
    static Matrix4 createMirror(const Vector3 &planeNormal, const Vector3 &pointOnPlane);
    static Matrix4 createOrient(const Vector3 &from, const Vector3 &to);
    static Matrix4 createRotate(const Vector3 &axis, float degrees);
    static Matrix4 createScale(float sx, float sy, float sz);
    static Matrix4 createTranslate(float tx, float ty, float tz);

    Matrix4() {}
    Matrix4(float m11, float m12, float m13, float m14,
            float m21, float m22, float m23, float m24,
            float m31, float m32, float m33, float m34,
            float m41, float m42, float m43, float m44);
    ~Matrix4() {}

    float *operator[](int row);
    const float *operator[](int row) const;

    bool operator==(const Matrix4 &rhs) const;
    bool operator!=(const Matrix4 &rhs) const;

    Matrix4 &operator+=(const Matrix4 &rhs);
    Matrix4 &operator-=(const Matrix4 &rhs);
    Matrix4 &operator*=(const Matrix4 &rhs);
    Matrix4 &operator*=(float scalar);
    Matrix4 &operator/=(float scalar);

    Matrix4 operator+(const Matrix4 &rhs) const;
    Matrix4 operator-(const Matrix4 &rhs) const;
    Matrix4 operator*(const Matrix4 &rhs) const;
    Matrix4 operator*(float scalar) const;
    Matrix4 operator/(float scalar) const;

    float determinant() const;
    void fromAxes(const Vector3 &x, const Vector3 &y, const Vector3 &z);
    void fromAxesTransposed(const Vector3 &x, const Vector3 &y, const Vector3 &z);
    void fromHeadPitchRoll(float headDegrees, float pitchDegrees, float rollDegrees);
    void identity();
    Matrix4 inverse() const;
    void orient(const Vector3 &from, const Vector3 &to);
    void rotate(const Vector3 &axis, float degrees);
    void scale(float sx, float sy, float sz);
    void toAxes(Vector3 &x, Vector3 &y, Vector3 &z) const;
    void toAxesTransposed(Vector3 &x, Vector3 &y, Vector3 &z) const;
    void toHeadPitchRoll(float &headDegrees, float &pitchDegrees, float &rollDegrees) const;
    void translate(float tx, float ty, float tz);
    Matrix4 transpose() const;

private:
    float mtx[4][4];
};

class CIwFMat
{
public:
/**
 * 3x3 rotation matrix.
 */
    float   m[3][3];
/**
 * Trans vector.
 */
    CIwFVec3    t;

...

};

Answer 1

您的转换看起来不错，但请检查：

Marmalade使用行列矩阵表示法和右手轴系统（记住你的转换）

橘子酱“视图”矩阵实际上不是视图矩阵，它是摄像机的位置和方向矩阵。要获得实际的视图矩阵，应该像这样做：

CIwFMat MarmaladeView = IwGxGetViewMatrix();
CIwFMat view = (CIwFMat(CIwFMat::g_Identity, -MarmaladeView.GetTrans()) * MarmaladeView.GetTranspose()); // actually it's simple matrix inversion, but CIwFMat doesn't have Inverse() method
// in some cases your should add axis-flip transform

marmalade IwGxGetPerspectiveMatrix（）在Ortographic投影的情况下返回无效的投影矩阵（文档没有说明这个有趣的事实）
LookAt（）函数只是设置矩阵的旋转部分以匹配2点之间的方向，所以手动翻译
检查远/近飞机

所有MVP矩阵都应由

明确设置

IwGxSetViewMatrix(); // sets view matrix view - camera position
IwGxSetModelMatrix(); // sets model matrix
IwGxSetPerspMul(); // sets perspective projection in terms of distance to view plane
IwGxSetFarZNearZ(); // sets clipping planes

3x3使用橘子酱查看矩阵

1 个答案: