在 Vulkan 中加载非二次幂纹理

Loading non-power-of-two textures in Vulkan

本文关键字：二次幂 纹理 加载 Vulkan      更新时间：2023-10-16

如果我的纹理尺寸是 2 的幂，我的 2D 纹理加载器工作正常，但当它们不是时，纹理数据显示为倾斜。我该如何解决这个问题？我认为这个问题与内存对齐和行间距有关。以下是我的加载程序代码的相关部分：

VkMemoryRequirements memReqs;
vkGetImageMemoryRequirements( GfxDeviceGlobal::device, mappableImage, &memReqs );
VkMemoryAllocateInfo memAllocInfo = {};
memAllocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
memAllocInfo.pNext = nullptr;
memAllocInfo.memoryTypeIndex = 0;
memAllocInfo.allocationSize = memReqs.size;
GetMemoryType( memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT, &memAllocInfo.memoryTypeIndex );
VkDeviceMemory mappableMemory;
err = vkAllocateMemory( GfxDeviceGlobal::device, &memAllocInfo, nullptr, &mappableMemory );
CheckVulkanResult( err, "vkAllocateMemory in Texture2D" );
err = vkBindImageMemory( GfxDeviceGlobal::device, mappableImage, mappableMemory, 0 );
CheckVulkanResult( err, "vkBindImageMemory in Texture2D" );
VkImageSubresource subRes = {};
subRes.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
subRes.mipLevel = 0;
subRes.arrayLayer = 0;
VkSubresourceLayout subResLayout;
vkGetImageSubresourceLayout( GfxDeviceGlobal::device, mappableImage, &subRes, &subResLayout );
void* mapped;
err = vkMapMemory( GfxDeviceGlobal::device, mappableMemory, 0, memReqs.size, 0, &mapped );
CheckVulkanResult( err, "vkMapMemory in Texture2D" );
const int bytesPerPixel = 4;
std::size_t dataSize = bytesPerPixel * width * height;
std::memcpy( mapped, data, dataSize );
vkUnmapMemory( GfxDeviceGlobal::device, mappableMemory );

从vkGetImageSubresourceLayout获得的VkSubresourceLayout将包含rowPitch成员中纹理的音高。它很可能不等于 width ，因此，当您对整个数据块进行memcpy时，您将相关数据复制到纹理的填充部分。

相反，您需要逐行memcpy，跳过映射纹理中的填充内存：

const int bytesPerPixel = 4;
std::size_t dataRowSize = bytesPerPixel * width;
char* mappedBytes = (char*)mapped;
for(int i = 0; i < height; ++i)
{
    std::memcpy(mapped, data, dataSize);
    mappedBytes += rowPitch;
    data += dataRowSize;
}

（此代码假设数据也是char * - 未给出其声明）

for(int i = 0; i < height; ++i)
{
    std::memcpy(mappedBytes, data, dataRowSize);
    mappedBytes += layout.rowPitch;
    data += dataRowSize;
}
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