Question

TransformationMatrices[mesh_count-1][0] = n->mTransformation.a1; 
TransformationMatrices[mesh_count-1][1] = n->mTransformation.a2;
TransformationMatrices[mesh_count-1][2] = n->mTransformation.a3;
TransformationMatrices[mesh_count-1][3] = n->mTransformation.a4;
TransformationMatrices[mesh_count-1][4] = n->mTransformation.b1;
TransformationMatrices[mesh_count-1][5] = n->mTransformation.b2;
TransformationMatrices[mesh_count-1][6] = n->mTransformation.b3;
TransformationMatrices[mesh_count-1][7] = n->mTransformation.b4;
TransformationMatrices[mesh_count-1][8] = n->mTransformation.c1;
TransformationMatrices[mesh_count-1][9] = n->mTransformation.c2;
TransformationMatrices[mesh_count-1][10] = n->mTransformation.c3;
TransformationMatrices[mesh_count-1][11] = n->mTransformation.c4;
TransformationMatrices[mesh_count-1][12] = n->mTransformation.d1;
TransformationMatrices[mesh_count-1][13] = n->mTransformation.d2;
TransformationMatrices[mesh_count-1][14] = n->mTransformation.d3;
TransformationMatrices[mesh_count-1][15] = n->mTransformation.d4;

编辑：替换为替换为较短的格式。

Answer 1

嗯，你有你的选择，

一种依赖的简单方法实现 - 定义布局规则。或
一种非常复杂的跨平台方式，但代码更多比你已经有了。

方法1）会是这样的：

 double *dest = &TransformationMatrices[mesh_count-1][0];
 double *src = &n->mTransformation.a1;    

 memcpy(dest, src, sizeof(double) * 16);

这取决于各种未定义的行为，应该工作.....

Answer 2

我不完全确定我会关注这个问题，但您可以使用预处理器来缩短这一点。例如，

int WriteIndex = 0;
#define WRITE_MATRIX(prefix) \
    do { \
        TransformationMatrices[mesh_count-1][WriteIndex++] = n->mTransformation.prefix ## 1; \
        TransformationMatrices[mesh_count-1][WriteIndex++] = n->mTransformation.prefix ## 2; \
        TransformationMatrices[mesh_count-1][WriteIndex++] = n->mTransformation.prefix ## 3; \
        TransformationMatrices[mesh_count-1][WriteIndex++] = n->mTransformation.prefix ## 4; \
    } while(0)
WRITE_MATRIX(a);
WRITE_MATRIX(b);
WRITE_MATRIX(c);
WRITE_MATRIX(d);

我不会用这种方式编写代码，但它演示了这种技术......

有没有一种简单的方法可以在C中替换它，而无需使用大型外部库？

2 个答案: