Add code to allow for depth buffer query (Fixes #18)

openVulkanoCpp/Vulkan/DepthBufferQuery.cpp

@@ -0,0 +1,96 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include "DepthBufferQuery.hpp"
+#include "Renderer.hpp"
+#include <vulkan/vulkan.hpp>
+
+//TODO resize
+
+namespace OpenVulkano::Vulkan
+{
+	void DepthBufferQuery::Init()
+	{
+		auto device = renderer.GetContext().device->device;
+
+		vk::BufferCreateInfo bufferInfo = { {}, 25 * sizeof(float), vk::BufferUsageFlagBits::eTransferDst };
+		bufferDepth = device.createBuffer(bufferInfo);
+		const vk::MemoryRequirements memRequirements = device.getBufferMemoryRequirements(bufferDepth);
+		size_t size = memRequirements.size;
+		const vk::MemoryAllocateInfo memAllocInfo = { size, renderer.GetContext().device->GetMemoryType(memRequirements.memoryTypeBits, vk::MemoryPropertyFlagBits::eHostCoherent | vk::MemoryPropertyFlagBits::eHostVisible) };
+
+		memory = device.allocateMemory(memAllocInfo);
+		cpuDepthBuffer = static_cast<float*>(device.mapMemory(memory, 0, VK_WHOLE_SIZE, {}));
+
+		device.bindBufferMemory(bufferDepth, memory, 0);
+	}
+
+	void DepthBufferQuery::Close()
+	{
+		auto device = renderer.GetContext().device->device;
+		device.destroy(bufferDepth);
+		device.unmapMemory(memory);
+		device.free(memory);
+		cpuDepthBuffer = nullptr;
+	}
+	
+	void DepthBufferQuery::Resize(uint32_t width, uint32_t height)
+	{
+		//TODO
+	}
+	
+	float DepthBufferQuery::GetQueriedValue() const
+	{
+		if (cpuDepthBuffer[0] == -2) return -2;
+		if (cpuDepthBuffer[12] > 0 && cpuDepthBuffer[12] < 1) return cpuDepthBuffer[12];
+		double val = 0;
+		int validCount = 0;
+		for (int i = 0; i < 25; i++)
+		{
+			float f = cpuDepthBuffer[i];
+			if (f > 0 && f < 1)
+			{
+				val += f;
+				validCount++;
+			}
+		}
+		if (validCount == 0) return 1; // Prevent divide by 0
+		return val / validCount;
+	}
+	
+	vk::Offset3D DepthBufferQuery::GetCopyOffset() const
+	{
+		vk::Extent3D depthExtent = renderer.GetContext().swapChain.GetCurrentDepthBuffer().extent;
+		
+		int32_t x = static_cast<int32_t>(depthQueryCoordinates.x * depthExtent.width);
+		x = std::min<int32_t>(depthExtent.width - 5, std::max(0, x));
+		
+		int32_t y = static_cast<int32_t>(depthQueryCoordinates.y * depthExtent.height);
+		y = std::min<int32_t>(depthExtent.height - 5, std::max(0, y));
+		
+		return { x, y, 0 };
+	}
+
+	void DepthBufferQuery::Encode(vk::CommandBuffer& commandBuffer)
+	{
+		if (!copyDepthBuffer) return;
+		copyDepthBuffer = false;
+		std::fill(cpuDepthBuffer, cpuDepthBuffer + 25, -2.0f); // Invalidate data in buffer to allow detecting if copy is done
+		const vk::ImageAspectFlags aspectMask = vk::ImageAspectFlagBits::eDepth | vk::ImageAspectFlagBits::eStencil;
+		const Image& depthBufferImage = renderer.GetContext().swapChain.GetCurrentDepthBuffer();
+
+		constexpr vk::Extent3D copySize = { 5, 5, 1 };
+		const vk::ImageSubresourceLayers layout = { vk::ImageAspectFlagBits::eDepth, 0, 0, 1 };
+		vk::BufferImageCopy imgCopy = { 0, 5, 5, layout, GetCopyOffset(), copySize };
+
+		const vk::ImageMemoryBarrier imgMemBarrier({}, vk::AccessFlagBits::eTransferRead, vk::ImageLayout::eDepthStencilAttachmentOptimal, vk::ImageLayout::eTransferSrcOptimal, 0, 0, depthBufferImage.image, vk::ImageSubresourceRange(aspectMask, 0, 1, 0, 1));
+		commandBuffer.pipelineBarrier(vk::PipelineStageFlagBits::eTopOfPipe, vk::PipelineStageFlagBits::eTransfer, {}, nullptr, nullptr, imgMemBarrier);
+
+		commandBuffer.copyImageToBuffer(depthBufferImage.image, vk::ImageLayout::eTransferSrcOptimal, bufferDepth, 1, &imgCopy);
+
+		depthBufferImage.SetLayout(commandBuffer, aspectMask, vk::ImageLayout::eDepthStencilAttachmentOptimal, vk::ImageLayout::eTransferSrcOptimal);
+	}
+}