我有点惊讶。我已经调试了几个小时的代码,而GLM似乎放弃了我。我在以下2个实例中挣扎:

....
cout << "multiplying A:" << endl;
displayMatrix(node->wMatrix);

cout << "and B:" << endl;
displayMatrix((node->children)[i]->wMatrix);

//switch order!
mat4 temp = (node->children)[i]->wMatrix * node->wMatrix;

cout << "Get result as:" << endl;
displayMatrix(temp);
...


displayMatrix方法如下:

void displayMatrix(mat4 &m)
{
    cout << m[0][0] << "  " << m[0][1] << "  " << m[0][2] << "  " << m[0][3] << endl;
    cout << m[1][0] << "  " << m[1][1] << "  " << m[1][2] << "  " << m[1][3] << endl;
    cout << m[2][0] << "  " << m[2][1] << "  " << m[2][2] << "  " << m[2][3] << endl;
    cout << m[3][0] << "  " << m[3][1] << "  " << m[3][2] << "  " << m[3][3] << endl;
}


这是我得到的输出:

multiplying A:
1  0  0  0
0  1  0  0.5
0  0  1  0
0  0  0  1
and B:
0.540302  -0.841471  0  0
0.841471  0.540302  0  -0.5
0  0  1  0
0  0  0  1
Get result as:
0.540302  -0.841471  0  0
0.841471  0.540302  0  0
0  0  1  0
0  0  0  1


注意,在上面的代码中,矩阵乘法的顺序与您在纸上写的相反。换句话说,代码显示为B *A。这让我很不满意。

第二个实例:

cout << "temp:" << endl;
cout << temp.x << "  " << temp.y << "  " << temp.z << "  " << temp.w << endl;

cout << "binding matrix inverse: " << endl;
displayMatrix(bindingInvs.at(jIndex));

temp = bindingInvs.at(jIndex) * temp;
cout << "now temp:" << endl;
cout << temp.x << "  " << temp.y << "  " << temp.z << "  " << temp.w << endl;

cout << "joint world matrix: " << endl;
displayMatrix(joints.at(jIndex)->wMatrix);
temp = (joints.at(jIndex)->wMatrix) * temp;
cout << "now temp:" << endl;
cout << temp.x << "  " << temp.y << "  " << temp.z << "  " << temp.w << endl;

cout << "weight: " << jWeight << endl;
temp = jWeight * temp;

cout << "now temp:" << endl;
cout << temp.x << "  " << temp.y << "  " << temp.z << "  " << temp.w << endl;


我现在得到的输出是:

temp:
0.087  0  -0.05  1
binding matrix inverse:
1  -0  0  -0
-0  1  -0  0
0  -0  1  -0
-0  0  -0  1
now temp:
0.087  0  -0.05  1
joint world matrix:
1  0  0  0
0  1  0  0.5
0  0  1  0
0  0  0  1
now temp:
0.087  0  -0.05  1
weight: 1
now temp:
0.087  0  -0.05  1


由于某种原因,温度永远不会改变。我不知道该怎么办,或者为什么会这样。我的程序可以编译并运行(我从上面的输出中粘贴)。当然,这不是整个程序。这只是调试步骤。但是我有信心,这足以说明发生了什么。

最佳答案

您的displayMatrix函数使您感到困惑,因为您打印的矩阵要换成您希望在纸上看到的矩阵。 GLM使用列主要顺序,因此寻址为m[col][row]

现在记住这一点,实际上是您应该期望的操作A*B

对于temp向量,会出现相同的问题:将其乘以的第一个​​矩阵是恒等,因此不变。第二个矩阵是单位,除了最后一行是0 0.5 0 1,因此x,y和z将保持不变,而新的w'将是0.5 * y + w。因为y首先是0,所以这里也没有任何改变。

关于c++ - GLM乘法顺序,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/26454838/

10-15 13:42