/*
* Vulkan Example - Displacement mapping with tessellation shaders
*
* Copyright (C) 2016 by Sascha Willems - www.saschawillems.de
*
* This code is licensed under the MIT license (MIT) (http://opensource.org/licenses/MIT)
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <vector>

#define GLM_FORCE_RADIANS
#define GLM_FORCE_DEPTH_ZERO_TO_ONE
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <gli/gli.hpp>

#include <vulkan/vulkan.h>
#include "vulkanexamplebase.h"
#include "vulkanMeshLoader.hpp"

#define VERTEX_BUFFER_BIND_ID 0
#define ENABLE_VALIDATION false
// Vertex layout for this example
std::vector<vkMeshLoader::VertexLayout> vertexLayout =
{
	vkMeshLoader::VERTEX_LAYOUT_POSITION,
	vkMeshLoader::VERTEX_LAYOUT_NORMAL,
	vkMeshLoader::VERTEX_LAYOUT_UV
};

class VulkanExample : public VulkanExampleBase
{
private:
	struct {
		vkTools::VulkanTexture colorHeightMap;
	} textures;
public:
	bool splitScreen = true;
	bool displacement = true;

	struct {
		VkPipelineVertexInputStateCreateInfo inputState;
		std::vector<VkVertexInputBindingDescription> bindingDescriptions;
		std::vector<VkVertexInputAttributeDescription> attributeDescriptions;
	} vertices;

	struct {
		vkMeshLoader::MeshBuffer object;
	} meshes;

	struct {
		vk::Buffer tessControl, tessEval;
	} uniformBuffers;

	struct UBOTessControl {
		float tessLevel = 64.0f;
	} uboTessControl;

	struct UBOTessEval {
		glm::mat4 projection;
		glm::mat4 model;
		glm::vec4 lightPos = glm::vec4(0.0f, -1.0f, 0.0f, 0.0f);
		float tessAlpha = 1.0f;
		float tessStrength = 0.1f;
	} uboTessEval;

	struct {
		VkPipeline solid;
		VkPipeline wireframe;
	} pipelines;

	VkPipelineLayout pipelineLayout;
	VkDescriptorSet descriptorSet;
	VkDescriptorSetLayout descriptorSetLayout;

	VulkanExample() : VulkanExampleBase(ENABLE_VALIDATION)
	{
		zoom = -1.25f;
		rotation = glm::vec3(-20.0f, 45.0f, 0.0f);
		enableTextOverlay = true;
		title = "Vulkan Example - Tessellation shader displacement mapping";
		// Enable physical device features required for this example				
		// Tell the driver that we are going to use geometry shaders
		enabledFeatures.tessellationShader = VK_TRUE;
		// Example also uses a wireframe pipeline, enable non-solid fill modes
		enabledFeatures.fillModeNonSolid = VK_TRUE;
	}

	~VulkanExample()
	{
		// Clean up used Vulkan resources 
		// Note : Inherited destructor cleans up resources stored in base class
		vkDestroyPipeline(device, pipelines.solid, nullptr);
		vkDestroyPipeline(device, pipelines.wireframe, nullptr);

		vkDestroyPipelineLayout(device, pipelineLayout, nullptr);
		vkDestroyDescriptorSetLayout(device, descriptorSetLayout, nullptr);

		uniformBuffers.tessControl.destroy();
		uniformBuffers.tessEval.destroy();

		vkMeshLoader::freeMeshBufferResources(device, &meshes.object);
		textureLoader->destroyTexture(textures.colorHeightMap);
	}

	void loadTextures()
	{
		textureLoader->loadTexture(
			getAssetPath() + "textures/pattern_36_bc3.ktx", 
			VK_FORMAT_BC3_UNORM_BLOCK, 
			&textures.colorHeightMap);
	}

	void reBuildCommandBuffers()
	{
		if (!checkCommandBuffers())
		{
			destroyCommandBuffers();
			createCommandBuffers();
		}
		buildCommandBuffers();
	}

	void buildCommandBuffers()
	{
		VkCommandBufferBeginInfo cmdBufInfo = vkTools::initializers::commandBufferBeginInfo();

		VkClearValue clearValues[2];
		clearValues[0].color = defaultClearColor;
		clearValues[1].depthStencil = { 1.0f, 0 };

		VkRenderPassBeginInfo renderPassBeginInfo = vkTools::initializers::renderPassBeginInfo();
		renderPassBeginInfo.renderPass = renderPass;
		renderPassBeginInfo.renderArea.offset.x = 0;
		renderPassBeginInfo.renderArea.offset.y = 0;
		renderPassBeginInfo.renderArea.extent.width = width;
		renderPassBeginInfo.renderArea.extent.height = height;
		renderPassBeginInfo.clearValueCount = 2;
		renderPassBeginInfo.pClearValues = clearValues;

		for (int32_t i = 0; i < drawCmdBuffers.size(); ++i)
		{
			// Set target frame buffer
			renderPassBeginInfo.framebuffer = frameBuffers[i];

			VK_CHECK_RESULT(vkBeginCommandBuffer(drawCmdBuffers[i], &cmdBufInfo));

			vkCmdBeginRenderPass(drawCmdBuffers[i], &renderPassBeginInfo, VK_SUBPASS_CONTENTS_INLINE);

			VkViewport viewport = vkTools::initializers::viewport((float)width, (float)height, 0.0f, 1.0f);
			vkCmdSetViewport(drawCmdBuffers[i], 0, 1, &viewport);

			VkRect2D scissor = vkTools::initializers::rect2D(splitScreen ? width / 2 : width, height, 0, 0);
			vkCmdSetScissor(drawCmdBuffers[i], 0, 1, &scissor);

			vkCmdSetLineWidth(drawCmdBuffers[i], 1.0f);

			vkCmdBindDescriptorSets(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &descriptorSet, 0, NULL);

			VkDeviceSize offsets[1] = { 0 };
			vkCmdBindVertexBuffers(drawCmdBuffers[i], VERTEX_BUFFER_BIND_ID, 1, &meshes.object.vertices.buf, offsets);
			vkCmdBindIndexBuffer(drawCmdBuffers[i], meshes.object.indices.buf, 0, VK_INDEX_TYPE_UINT32);

			if (splitScreen)
			{
				vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelines.wireframe);
				vkCmdDrawIndexed(drawCmdBuffers[i], meshes.object.indexCount, 1, 0, 0, 0);
				scissor.offset.x = width / 2;
				vkCmdSetScissor(drawCmdBuffers[i], 0, 1, &scissor);
			}

			vkCmdBindPipeline(drawCmdBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelines.solid);
			vkCmdDrawIndexed(drawCmdBuffers[i], meshes.object.indexCount, 1, 0, 0, 0);

			vkCmdEndRenderPass(drawCmdBuffers[i]);

			VK_CHECK_RESULT(vkEndCommandBuffer(drawCmdBuffers[i]));
		}
	}

	void loadMeshes()
	{
		loadMesh(getAssetPath() + "models/plane.obj", &meshes.object, vertexLayout, 0.25f);
	}

	void setupVertexDescriptions()
	{
		// Binding description
		vertices.bindingDescriptions.resize(1);
		vertices.bindingDescriptions[0] =
			vkTools::initializers::vertexInputBindingDescription(
				VERTEX_BUFFER_BIND_ID,
				vkMeshLoader::vertexSize(vertexLayout),
				VK_VERTEX_INPUT_RATE_VERTEX);

		// Attribute descriptions
		// Describes memory layout and shader positions
		vertices.attributeDescriptions.resize(3);

		// Location 0 : Position
		vertices.attributeDescriptions[0] =
			vkTools::initializers::vertexInputAttributeDescription(
				VERTEX_BUFFER_BIND_ID,
				0,
				VK_FORMAT_R32G32B32_SFLOAT,
				0);

		// Location 1 : Normals
		vertices.attributeDescriptions[1] =
			vkTools::initializers::vertexInputAttributeDescription(
				VERTEX_BUFFER_BIND_ID,
				1,
				VK_FORMAT_R32G32B32_SFLOAT,
				sizeof(float) * 3);

		// Location 2 : Texture coordinates
		vertices.attributeDescriptions[2] =
			vkTools::initializers::vertexInputAttributeDescription(
				VERTEX_BUFFER_BIND_ID,
				2,
				VK_FORMAT_R32G32_SFLOAT,
				sizeof(float) * 6);

		vertices.inputState = vkTools::initializers::pipelineVertexInputStateCreateInfo();
		vertices.inputState.vertexBindingDescriptionCount = vertices.bindingDescriptions.size();
		vertices.inputState.pVertexBindingDescriptions = vertices.bindingDescriptions.data();
		vertices.inputState.vertexAttributeDescriptionCount = vertices.attributeDescriptions.size();
		vertices.inputState.pVertexAttributeDescriptions = vertices.attributeDescriptions.data();
	}

	void setupDescriptorPool()
	{
		// Example uses two ubos and two image samplers
		std::vector<VkDescriptorPoolSize> poolSizes =
		{
			vkTools::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 2),
			vkTools::initializers::descriptorPoolSize(VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1)
		};

		VkDescriptorPoolCreateInfo descriptorPoolInfo =
			vkTools::initializers::descriptorPoolCreateInfo(
				poolSizes.size(),
				poolSizes.data(),
				2);

		VK_CHECK_RESULT(vkCreateDescriptorPool(device, &descriptorPoolInfo, nullptr, &descriptorPool));
	}

	void setupDescriptorSetLayout()
	{
		std::vector<VkDescriptorSetLayoutBinding> setLayoutBindings =
		{
			// Binding 0 : Tessellation control shader ubo
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 
				VK_SHADER_STAGE_TESSELLATION_CONTROL_BIT, 
				0),
			// Binding 1 : Tessellation evaluation shader ubo
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
				VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT, 
				1),
			// Binding 2 : Combined color (rgb) and height (alpha) map
			vkTools::initializers::descriptorSetLayoutBinding(
				VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
				VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT | VK_SHADER_STAGE_FRAGMENT_BIT,
				2),
		};

		VkDescriptorSetLayoutCreateInfo descriptorLayout =
			vkTools::initializers::descriptorSetLayoutCreateInfo(
				setLayoutBindings.data(),
				setLayoutBindings.size());

		VK_CHECK_RESULT(vkCreateDescriptorSetLayout(device, &descriptorLayout, nullptr, &descriptorSetLayout));

		VkPipelineLayoutCreateInfo pPipelineLayoutCreateInfo =
			vkTools::initializers::pipelineLayoutCreateInfo(
				&descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkCreatePipelineLayout(device, &pPipelineLayoutCreateInfo, nullptr, &pipelineLayout));
	}

	void setupDescriptorSet()
	{
		VkDescriptorSetAllocateInfo allocInfo = 
			vkTools::initializers::descriptorSetAllocateInfo(
				descriptorPool,
				&descriptorSetLayout,
				1);

		VK_CHECK_RESULT(vkAllocateDescriptorSets(device, &allocInfo, &descriptorSet));

		// Color and height map image descriptor
		VkDescriptorImageInfo texDescriptor =
			vkTools::initializers::descriptorImageInfo(
				textures.colorHeightMap.sampler,
				textures.colorHeightMap.view,
				VK_IMAGE_LAYOUT_GENERAL);

		std::vector<VkWriteDescriptorSet> writeDescriptorSets =
		{
			// Binding 0 : Tessellation control shader ubo
			vkTools::initializers::writeDescriptorSet(
				descriptorSet, 
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 
				0, 
				&uniformBuffers.tessControl.descriptor),
			// Binding 1 : Tessellation evaluation shader ubo
			vkTools::initializers::writeDescriptorSet(
				descriptorSet, 
				VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER,
				1, 
				&uniformBuffers.tessEval.descriptor),
			// Binding 2 : Color and displacement map (alpha channel)
			vkTools::initializers::writeDescriptorSet(
				descriptorSet,
				VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER,
				2,
				&texDescriptor),
		};

		vkUpdateDescriptorSets(device, writeDescriptorSets.size(), writeDescriptorSets.data(), 0, NULL);
	}

	void preparePipelines()
	{
		VkPipelineInputAssemblyStateCreateInfo inputAssemblyState =
			vkTools::initializers::pipelineInputAssemblyStateCreateInfo(
				VK_PRIMITIVE_TOPOLOGY_PATCH_LIST,
				0,
				VK_FALSE);

		VkPipelineRasterizationStateCreateInfo rasterizationState =
			vkTools::initializers::pipelineRasterizationStateCreateInfo(
				VK_POLYGON_MODE_FILL,
				VK_CULL_MODE_NONE,
				VK_FRONT_FACE_COUNTER_CLOCKWISE,
				0);

		VkPipelineColorBlendAttachmentState blendAttachmentState =
			vkTools::initializers::pipelineColorBlendAttachmentState(
				0xf,
				VK_FALSE);

		VkPipelineColorBlendStateCreateInfo colorBlendState =
			vkTools::initializers::pipelineColorBlendStateCreateInfo(
				1,
				&blendAttachmentState);

		VkPipelineDepthStencilStateCreateInfo depthStencilState =
			vkTools::initializers::pipelineDepthStencilStateCreateInfo(
				VK_TRUE,
				VK_TRUE,
				VK_COMPARE_OP_LESS_OR_EQUAL);

		VkPipelineViewportStateCreateInfo viewportState =
			vkTools::initializers::pipelineViewportStateCreateInfo(1, 1, 0);

		VkPipelineMultisampleStateCreateInfo multisampleState =
			vkTools::initializers::pipelineMultisampleStateCreateInfo(
				VK_SAMPLE_COUNT_1_BIT,
				0);

		std::vector<VkDynamicState> dynamicStateEnables = {
			VK_DYNAMIC_STATE_VIEWPORT,
			VK_DYNAMIC_STATE_SCISSOR,
			VK_DYNAMIC_STATE_LINE_WIDTH
		};
		VkPipelineDynamicStateCreateInfo dynamicState =
			vkTools::initializers::pipelineDynamicStateCreateInfo(
				dynamicStateEnables.data(),
				dynamicStateEnables.size(),
				0);

		VkPipelineTessellationStateCreateInfo tessellationState =
			vkTools::initializers::pipelineTessellationStateCreateInfo(3);

		// Tessellation pipeline
		// Load shaders
		std::array<VkPipelineShaderStageCreateInfo, 4> shaderStages;
		shaderStages[0] = loadShader(getAssetPath() + "shaders/displacement/base.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
		shaderStages[1] = loadShader(getAssetPath() + "shaders/displacement/base.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);
		shaderStages[2] = loadShader(getAssetPath() + "shaders/displacement/displacement.tesc.spv", VK_SHADER_STAGE_TESSELLATION_CONTROL_BIT);
		shaderStages[3] = loadShader(getAssetPath() + "shaders/displacement/displacement.tese.spv", VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT);

		VkGraphicsPipelineCreateInfo pipelineCreateInfo =
			vkTools::initializers::pipelineCreateInfo(
				pipelineLayout,
				renderPass,
				0);

		pipelineCreateInfo.pVertexInputState = &vertices.inputState;
		pipelineCreateInfo.pInputAssemblyState = &inputAssemblyState;
		pipelineCreateInfo.pRasterizationState = &rasterizationState;
		pipelineCreateInfo.pColorBlendState = &colorBlendState;
		pipelineCreateInfo.pMultisampleState = &multisampleState;
		pipelineCreateInfo.pViewportState = &viewportState;
		pipelineCreateInfo.pDepthStencilState = &depthStencilState;
		pipelineCreateInfo.pDynamicState = &dynamicState;
		pipelineCreateInfo.pTessellationState = &tessellationState;
		pipelineCreateInfo.stageCount = shaderStages.size();
		pipelineCreateInfo.pStages = shaderStages.data();
		pipelineCreateInfo.renderPass = renderPass;

		// Solid pipeline
		rasterizationState.cullMode = VK_CULL_MODE_BACK_BIT;
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipelines.solid));
		// Wireframe pipeline
		rasterizationState.polygonMode = VK_POLYGON_MODE_LINE;
		rasterizationState.cullMode = VK_CULL_MODE_NONE;
		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipelines.wireframe));
	}

	// Prepare and initialize uniform buffer containing shader uniforms
	void prepareUniformBuffers()
	{
		// Tessellation evaluation shader uniform buffer
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&uniformBuffers.tessEval,
			sizeof(uboTessEval)));

		// Tessellation control shader uniform buffer
		VK_CHECK_RESULT(vulkanDevice->createBuffer(
			VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
			VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
			&uniformBuffers.tessControl,
			sizeof(uboTessControl)));

		// Map persistent
		VK_CHECK_RESULT(uniformBuffers.tessControl.map());
		VK_CHECK_RESULT(uniformBuffers.tessEval.map());

		updateUniformBuffers();
	}

	void updateUniformBuffers()
	{
		// Tessellation eval
		glm::mat4 viewMatrix = glm::mat4();
		uboTessEval.projection = glm::perspective(glm::radians(45.0f), (float)(width) / (float)height, 0.1f, 256.0f);
		viewMatrix = glm::translate(viewMatrix, glm::vec3(0.0f, 0.0f, zoom));

		float offset = 0.5f;
		int uboIndex = 1;
		uboTessEval.model = glm::mat4();
		uboTessEval.model = viewMatrix * glm::translate(uboTessEval.model, glm::vec3(0, 0, 0));
		uboTessEval.model = glm::rotate(uboTessEval.model, glm::radians(rotation.x), glm::vec3(1.0f, 0.0f, 0.0f));
		uboTessEval.model = glm::rotate(uboTessEval.model, glm::radians(rotation.y), glm::vec3(0.0f, 1.0f, 0.0f));
		uboTessEval.model = glm::rotate(uboTessEval.model, glm::radians(rotation.z), glm::vec3(0.0f, 0.0f, 1.0f));

		uboTessEval.lightPos.y = -0.5f - uboTessEval.tessStrength;

		memcpy(uniformBuffers.tessEval.mapped, &uboTessEval, sizeof(uboTessEval));

		// Tessellation control
		float savedLevel = uboTessControl.tessLevel;
		if (!displacement)
		{
			uboTessControl.tessLevel = 1.0f;
		}

		memcpy(uniformBuffers.tessControl.mapped, &uboTessControl, sizeof(uboTessControl));

		if (!displacement)
		{
			uboTessControl.tessLevel = savedLevel;
		}
	}

	void draw()
	{
		VulkanExampleBase::prepareFrame();

		// Command buffer to be sumitted to the queue
		submitInfo.commandBufferCount = 1;
		submitInfo.pCommandBuffers = &drawCmdBuffers[currentBuffer];

		// Submit to queue
		VK_CHECK_RESULT(vkQueueSubmit(queue, 1, &submitInfo, VK_NULL_HANDLE));

		VulkanExampleBase::submitFrame();
	}

	void prepare()
	{
		// Check if device supports tessellation shaders
		if (!deviceFeatures.tessellationShader)
		{
			vkTools::exitFatal("Selected GPU does not support tessellation shaders!", "Feature not supported");
		}

		VulkanExampleBase::prepare();
		loadMeshes();
		loadTextures();
		setupVertexDescriptions();
		prepareUniformBuffers();
		setupDescriptorSetLayout();
		preparePipelines();
		setupDescriptorPool();
		setupDescriptorSet();
		buildCommandBuffers();
		prepared = true;
	}

	virtual void render()
	{
		if (!prepared)
			return;
		draw();
	}

	virtual void viewChanged()
	{
		updateUniformBuffers();
	}

	void changeTessellationLevel(float delta)
	{
		uboTessControl.tessLevel += delta;
		uboTessControl.tessLevel = fmax(1.0, fmin(uboTessControl.tessLevel, 32.0));
		updateUniformBuffers();
		updateTextOverlay();
	}

	void changeTessellationStrength(float delta)
	{
		uboTessEval.tessStrength += delta;
		uboTessEval.tessStrength = fmax(0.0f, fmin(uboTessEval.tessStrength, 1.0f));
		updateUniformBuffers();
		updateTextOverlay();
	}

	void toggleSplitScreen()
	{
		splitScreen = !splitScreen;
		reBuildCommandBuffers();
		updateUniformBuffers();
	}

	void toggleDisplacement()
	{
		displacement = !displacement;
		updateUniformBuffers();
	}

	virtual void keyPressed(uint32_t keyCode)
	{
		switch (keyCode)
		{
		case KEY_KPADD:
		case GAMEPAD_BUTTON_R1:
			changeTessellationStrength(0.025);
			break;
		case KEY_KPSUB:
		case GAMEPAD_BUTTON_L1:
			changeTessellationStrength(-0.025);
			break;
		case KEY_D:
		case GAMEPAD_BUTTON_A:
			toggleDisplacement();
			break;
		case KEY_S:
		case GAMEPAD_BUTTON_X:
			toggleSplitScreen();
			break;
		}
	}

	virtual void getOverlayText(VulkanTextOverlay *textOverlay)
	{
		std::stringstream ss;
		ss << std::setprecision(2) << std::fixed << uboTessEval.tessStrength;
#if defined(__ANDROID__)
		textOverlay->addText("Tessellation height: " + ss.str() + " (Buttons L1/R1)", 5.0f, 85.0f, VulkanTextOverlay::alignLeft);
		textOverlay->addText("\"Button A\" to toggle displacement", 5.0f, 100.0f, VulkanTextOverlay::alignLeft);
		textOverlay->addText("\"Button X\" to toggle splitscreen", 5.0f, 115.0f, VulkanTextOverlay::alignLeft);
#else
		textOverlay->addText("Tessellation height: " + ss.str() + " (numpad +/-)", 5.0f, 85.0f, VulkanTextOverlay::alignLeft);
		textOverlay->addText("\"d\" to toggle displacement", 5.0f, 100.0f, VulkanTextOverlay::alignLeft);
		textOverlay->addText("\"s\" to toggle splitscreen", 5.0f, 115.0f, VulkanTextOverlay::alignLeft);
#endif
	}
};

VULKAN_EXAMPLE_MAIN()