<Vulkan> 使用渲染的 vkImage 作为纹理

Question

我想使用在之前的渲染通道中渲染的vkImage作为纹理在片段着色器中做复合操作。从这里我学会了vkCmdPipelineBarrier是用来等待GPU完成渲染操作，我写这个代码。它在骁龙设备上运行良好。但马利- g52上没有。部分发生写后写错误。这个代码还不够吗?有什么建议吗?

vkCmdEndRenderPass(cb);
vkCmdBeginRenderPass(cb, &renderPassBeginInfo, VK_SUBPASS_CONTENTS_INLINE);
VkViewport viewport = vks::initializers::viewport((float)offscreenPass.width, (float)offscreenPass.height, 0.0f, 1.0f);
vkCmdSetViewport(cb, 0, 1, &viewport);
VkRect2D scissor = vks::initializers::rect2D(offscreenPass.width, offscreenPass.height, 0, 0);
vkCmdSetScissor(cb, 0, 1, &scissor);
// https://github.com/KhronosGroup/Vulkan-Samples/blob/master/samples/performance/pipeline_barriers/pipeline_barriers.cpp
VkImageMemoryBarrier imageMemoryBarrier = vks::initializers::imageMemoryBarrier();
imageMemoryBarrier.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
imageMemoryBarrier.newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
imageMemoryBarrier.srcAccessMask = 0;
imageMemoryBarrier.dstAccessMask = 0;
imageMemoryBarrier.image = offscreenPass.color[drawframe].image;
imageMemoryBarrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
imageMemoryBarrier.subresourceRange.baseMipLevel = 0;
imageMemoryBarrier.subresourceRange.levelCount = 1;
imageMemoryBarrier.subresourceRange.baseArrayLayer = 0;
imageMemoryBarrier.subresourceRange.layerCount = 1;
vkCmdPipelineBarrier(
cb,
VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT,
VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT,
0, 0, nullptr, 0, nullptr, 1, &imageMemoryBarrier);
imageMemoryBarrier.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED;
imageMemoryBarrier.newLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL;
imageMemoryBarrier.image = offscreenPass.depth.image;
imageMemoryBarrier.srcAccessMask = 0;
imageMemoryBarrier.dstAccessMask = 0;
vkCmdPipelineBarrier(
cb,
VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT,
VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT,
0, 0, nullptr, 0, nullptr, 1, &imageMemoryBarrier);

我已经试过了这里写的每一种模式。

Answer 1

如果你想同步渲染通道，那么你的管道屏障必须在命令流中的渲染通道之外。也就是说，它必须在第一次通过的vkCmdEndRenderPass()之后，在第二次通过的vkCmdBeginRenderPass()之前。在渲染通道内发出的管道屏障，如您当前所做的，仅用于当前子通道内的同步。

同时，尽量避免:

srcStage=VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
dstStage=VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT

…对于管道屏障，当你只消耗第一个通道的输出作为第二个通道的片段着色器输入时。这是过于保守的，并且不必要地序列化几何处理的执行。在这种情况下，您应该使用:

srcStage=VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT
dstStage=VK_PIPELINE_STAGE_FRAGMENT_BIT

…这允许第二个通道的非依赖顶点着色和分组与第一个通道并行运行。

Answer 2

自解

Adreno和Mali在sampler2D精度上的差异导致了这个问题。我可以使用"精度高采样器"读取正确的数据。