c++ - 指向纹理数据的指针 - 垂直翻转数据

Question

我使用一个库来加载纹理，它返回一个指向数据、图像宽度和高度的指针。我想垂直翻转纹理数据，所以我创建了以下函数:

void FlipYTexture(const unsigned int width, const unsigned int height, uint8_t* data)
{
    const unsigned int rowsSwapCount = height / 2;
    const unsigned int maxRowIndex = height - 1;

    for (int i = 0; i < rowsSwapCount; ++i)
    {
        for (int j = 0; j < width; ++j)
        {
            const unsigned int currentDataIndex = width * i + j;
            const unsigned int swapDataIndex = width * (maxRowIndex - i) + j;

            uint8_t temp = data[currentDataIndex];
            data[currentDataIndex] = data[swapDataIndex];
            data[swapDataIndex] = temp;
        }
    } 
}

有什么方法可以优化该功能和/或更简单地实现它吗？

Answer 1

如果您可以将数据参数从指向数组引用的指针更改，那么这将是一个更简单的选项，尽管我不知道如果不使用典型输入数据对其进行测试它会更快。

#include <algorithm>

template<typename T, size_t N> 
void FlipYTexture(const unsigned int width, const unsigned int height, T(&data)[N]) {
    std::reverse(std::begin(data), std::end(data));
}

如果您必须将数据参数保留为指针，那么您至少可以使用 std::swap:

#include <utility>

void FlipYTexture(const unsigned int width, const unsigned int height, uint8_t* data) {
    const unsigned int rowsSwapCount = height / 2;
    const unsigned int maxRowIndex = height - 1;

    for (unsigned int i = 0; i < rowsSwapCount; ++i) {
        for (unsigned int j = 0; j < width; ++j) {
            const unsigned int currentDataIndex = width * i + j;
            const unsigned int swapDataIndex = width * (maxRowIndex - i) + j;
            std::swap(data[currentDataIndex], data[swapDataIndex]);
        }
    }
}