From e636b8eae5bba7391b67fdd3ae36f49c8d6f26a4 Mon Sep 17 00:00:00 2001
From: GeorgH93 <git@georgh93.eu>
Date: Sun, 23 May 2021 20:47:23 +0200
Subject: [PATCH] Add option to enable alpha blending

---
 openVulkanoCpp/Scene/Shader.hpp              |  1 +
 openVulkanoCpp/Vulkan/Pipeline.hpp           |  4 ++--
 openVulkanoCpp/Vulkan/Renderer.cpp           |  3 ++-
 openVulkanoCpp/Vulkan/Scene/VulkanShader.cpp | 10 ++++++++++
 4 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/openVulkanoCpp/Scene/Shader.hpp b/openVulkanoCpp/Scene/Shader.hpp
index d6e4056..66cdd1d 100644
--- a/openVulkanoCpp/Scene/Shader.hpp
+++ b/openVulkanoCpp/Scene/Shader.hpp
@@ -132,6 +132,7 @@ namespace openVulkanoCpp::Scene
 		Topology topology = Topology::TRIANGLE_LIST;
 		CullMode cullMode = CullMode::BACK;
 		ICloseable* renderShader = nullptr;
+		bool alphaBlend = false; // TODO allow fine control over blending
 
 		Shader() = default;
 		~Shader() override { if (renderShader) Shader::Close(); }
diff --git a/openVulkanoCpp/Vulkan/Pipeline.hpp b/openVulkanoCpp/Vulkan/Pipeline.hpp
index 365ee7c..ea64a03 100644
--- a/openVulkanoCpp/Vulkan/Pipeline.hpp
+++ b/openVulkanoCpp/Vulkan/Pipeline.hpp
@@ -34,8 +34,8 @@ namespace openVulkanoCpp::Vulkan
 	private:
 		void CreatePipelineLayout()
 		{
-			vk::PushConstantRange camPushConstantDesc = { vk::ShaderStageFlagBits::eVertex, 0, 3 * sizeof(Math::Matrix4f) + sizeof(Math::Vector4f) };
-			vk::PushConstantRange camPushConstantDescFrag = { vk::ShaderStageFlagBits::eFragment, 0, 3 * sizeof(Math::Matrix4f) + sizeof(Math::Vector4f) };
+			vk::PushConstantRange camPushConstantDesc = { vk::ShaderStageFlagBits::eVertex, 0, 3 * sizeof(Math::Matrix4f) + sizeof(Math::Vector4f) + 4 * sizeof(float) };
+			vk::PushConstantRange camPushConstantDescFrag = { vk::ShaderStageFlagBits::eFragment, camPushConstantDesc.size, camPushConstantDesc.size };
 			std::array<vk::PushConstantRange, 2> camPushConstantDescs = { camPushConstantDesc, camPushConstantDescFrag };
 			vk::DescriptorSetLayoutBinding nodeLayoutBinding = { 0, vk::DescriptorType::eUniformBufferDynamic, 1, vk::ShaderStageFlagBits::eVertex };
 			std::array<vk::DescriptorSetLayoutBinding, 1> layoutBindings = { nodeLayoutBinding };
diff --git a/openVulkanoCpp/Vulkan/Renderer.cpp b/openVulkanoCpp/Vulkan/Renderer.cpp
index d0ebde8..2ee50ef 100644
--- a/openVulkanoCpp/Vulkan/Renderer.cpp
+++ b/openVulkanoCpp/Vulkan/Renderer.cpp
@@ -146,8 +146,9 @@ namespace openVulkanoCpp::Vulkan
 		cmdHelper->Reset();
 		vk::CommandBufferInheritanceInfo inheritance = { context.swapChainRenderPass.renderPass, 0, context.swapChainRenderPass.GetFrameBuffer()->GetCurrentFrameBuffer() };
 		cmdHelper->cmdBuffer.begin(vk::CommandBufferBeginInfo{ vk::CommandBufferUsageFlagBits::eOneTimeSubmit | vk::CommandBufferUsageFlagBits::eRenderPassContinue, &inheritance });
+		cmdHelper->cmdBuffer.pushConstants(context.pipeline.pipelineLayout, vk::ShaderStageFlagBits::eVertex, 0, 3 * sizeof(Math::Matrix4f) + sizeof(Math::Vector4f) + 4 * sizeof(float), &scene->GetCamera()->GetViewProjectionMatrix());
+
 		shader->Record(cmdHelper->cmdBuffer, currentImageId);
-		cmdHelper->cmdBuffer.pushConstants(context.pipeline.pipelineLayout, vk::ShaderStageFlagBits::eVertex, 0, 3 * sizeof(Math::Matrix4f) + sizeof(Math::Vector4f), &scene->GetCamera()->GetViewProjectionMatrix());
 		Scene::Drawable** drawablePointer;
 		while((drawablePointer = jobQueue->Pop()) != nullptr)
 		{
diff --git a/openVulkanoCpp/Vulkan/Scene/VulkanShader.cpp b/openVulkanoCpp/Vulkan/Scene/VulkanShader.cpp
index cb00abd..fd7e24d 100644
--- a/openVulkanoCpp/Vulkan/Scene/VulkanShader.cpp
+++ b/openVulkanoCpp/Vulkan/Scene/VulkanShader.cpp
@@ -73,6 +73,16 @@ namespace openVulkanoCpp::Vulkan
 		depth.maxDepthBounds = 1;
 		vk::PipelineColorBlendAttachmentState colorBlendAttachment = {};
 		colorBlendAttachment.colorWriteMask = vk::ColorComponentFlagBits::eA | vk::ColorComponentFlagBits::eB | vk::ColorComponentFlagBits::eG | vk::ColorComponentFlagBits::eR;
+		if (shader->alphaBlend)
+		{
+			colorBlendAttachment.blendEnable = true;
+			colorBlendAttachment.srcColorBlendFactor = vk::BlendFactor::eSrcAlpha;
+			colorBlendAttachment.dstColorBlendFactor = vk::BlendFactor::eOneMinusSrcAlpha;
+			colorBlendAttachment.colorBlendOp = vk::BlendOp::eAdd;
+			colorBlendAttachment.srcAlphaBlendFactor = vk::BlendFactor::eOne;
+			colorBlendAttachment.dstAlphaBlendFactor = vk::BlendFactor::eZero;
+			colorBlendAttachment.alphaBlendOp = vk::BlendOp::eAdd;
+		}
 		vk::PipelineColorBlendStateCreateInfo colorInfo = {};
 		colorInfo.attachmentCount = 1;
 		colorInfo.pAttachments = &colorBlendAttachment;