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Resolve WRITE_AFTER_WRITE hazard in extensions sample debug_utils #1539

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Resolve WRITE_AFTER_WRITE hazard in extensions sample debug_utils #1539

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28 changes: 20 additions & 8 deletions samples/extensions/debug_utils/debug_utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -470,7 +470,11 @@ void DebugUtils::build_command_buffers()
vkCmdEndRenderPass(draw_cmd_buffers[i]);

cmd_end_label(draw_cmd_buffers[i]);
cmd_end_label(draw_cmd_buffers[i]);

if (bloom)
{
cmd_end_label(draw_cmd_buffers[i]);
}
}

VK_CHECK(vkEndCommandBuffer(draw_cmd_buffers[i]));
Expand Down Expand Up @@ -595,27 +599,35 @@ void DebugUtils::prepare_offscreen_buffer()
// Use subpass dependencies for attachment layout transitions
std::array<VkSubpassDependency, 2> dependencies{};

// vkCmdBeginRenderPass clears the color aspect of attachment 0 (offscreen.color[0]) and 1 (offscreen.color[1]) in subpass 0 of VkRenderPass offscreen.render_pass
// (loadOp VK_ATTACHMENT_LOAD_OP_CLEAR), which was previously written during an image layout transition initiated by the same command.
// For correct synchronization, the dependency from external to subpass 0 must allow VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT access at VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT.
dependencies[0].srcSubpass = VK_SUBPASS_EXTERNAL;
dependencies[0].dstSubpass = 0;
dependencies[0].srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
dependencies[0].dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
dependencies[0].srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT;
dependencies[0].dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
dependencies[0].dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

dependencies[1].srcSubpass = 0;
dependencies[1].dstSubpass = VK_SUBPASS_EXTERNAL;
// vkCmdBeginRenderPass clears the depth aspect of attachment 2 (offscreen.depth) in subpass 0 of VkRenderPass offscreen.render_pass (loadOp VK_ATTACHMENT_LOAD_OP_CLEAR),
// which was previously written during an image layout transition initiated by the same command.
// For correct synchronization, the dependency from external to subpass 0 must also allow VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT access at VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT.
dependencies[1].srcSubpass = VK_SUBPASS_EXTERNAL;
dependencies[1].dstSubpass = 0;
dependencies[1].srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
dependencies[1].dstStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
dependencies[1].srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
dependencies[1].dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
dependencies[1].dstStageMask = VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT;
dependencies[1].srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_READ_BIT;
dependencies[1].dstAccessMask = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT;

// No need for a dependency from subpass 0 to external

VkRenderPassCreateInfo render_pass_create_info = {};
render_pass_create_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
render_pass_create_info.pAttachments = attachment_descriptions.data();
render_pass_create_info.attachmentCount = static_cast<uint32_t>(attachment_descriptions.size());
render_pass_create_info.subpassCount = 1;
render_pass_create_info.pSubpasses = &subpass;
render_pass_create_info.dependencyCount = 2;
render_pass_create_info.dependencyCount = static_cast<uint32_t>(dependencies.size());
render_pass_create_info.pDependencies = dependencies.data();

VK_CHECK(vkCreateRenderPass(get_device().get_handle(), &render_pass_create_info, nullptr, &offscreen.render_pass));
Expand Down
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