hello_vulkan.cpp

/*
 * Copyright (c) 2014-2021, NVIDIA CORPORATION.  All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-FileCopyrightText: Copyright (c) 2014-2021 NVIDIA CORPORATION
 * SPDX-License-Identifier: Apache-2.0
 */


#include <sstream>


#define STB_IMAGE_IMPLEMENTATION
#include "obj_loader.h"
#include "stb_image.h"

#include "hello_vulkan.h"
#include "nvh/alignment.hpp"
#include "nvh/cameramanipulator.hpp"
#include "nvh/fileoperations.hpp"
#include "nvvk/commands_vk.hpp"
#include "nvvk/descriptorsets_vk.hpp"
#include "nvvk/images_vk.hpp"
#include "nvvk/pipeline_vk.hpp"
#include "nvvk/renderpasses_vk.hpp"
#include "nvvk/shaders_vk.hpp"
#include "nvvk/buffers_vk.hpp"

extern std::vector<std::string> defaultSearchPaths;


//--------------------------------------------------------------------------------------------------
// Keep the handle on the device
// Initialize the tool to do all our allocations: buffers, images
//
void HelloVulkan::setup(const VkInstance& instance, const VkDevice& device, const VkPhysicalDevice& physicalDevice, uint32_t queueFamily)
{
  AppBaseVk::setup(instance, device, physicalDevice, queueFamily);
  m_alloc.init(instance, device, physicalDevice);
  m_debug.setup(m_device);
  m_offscreenDepthFormat = nvvk::findDepthFormat(physicalDevice);
}

//--------------------------------------------------------------------------------------------------
// Called at each frame to update the camera matrix
//
void HelloVulkan::updateUniformBuffer(const VkCommandBuffer& cmdBuf)
{
  // Prepare new UBO contents on host.
  const float    aspectRatio = m_size.width / static_cast<float>(m_size.height);
  GlobalUniforms hostUBO     = {};
  const auto&    view        = CameraManip.getMatrix();
  const auto&    proj        = nvmath::perspectiveVK(CameraManip.getFov(), aspectRatio, 0.1f, 1000.0f);
  // proj[1][1] *= -1;  // Inverting Y for Vulkan (not needed with perspectiveVK).

  hostUBO.viewProj    = proj * view;
  hostUBO.viewInverse = nvmath::invert(view);
  hostUBO.projInverse = nvmath::invert(proj);

  // UBO on the device, and what stages access it.
  VkBuffer deviceUBO      = m_bGlobals.buffer;
  auto     uboUsageStages = VK_PIPELINE_STAGE_VERTEX_SHADER_BIT | VK_PIPELINE_STAGE_RAY_TRACING_SHADER_BIT_KHR;

  // Ensure that the modified UBO is not visible to previous frames.
  VkBufferMemoryBarrier beforeBarrier{VK_STRUCTURE_TYPE_BUFFER_MEMORY_BARRIER};
  beforeBarrier.srcAccessMask = VK_ACCESS_SHADER_READ_BIT;
  beforeBarrier.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
  beforeBarrier.buffer        = deviceUBO;
  beforeBarrier.offset        = 0;
  beforeBarrier.size          = sizeof(hostUBO);
  vkCmdPipelineBarrier(cmdBuf, uboUsageStages, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_DEPENDENCY_DEVICE_GROUP_BIT, 0,
                       nullptr, 1, &beforeBarrier, 0, nullptr);


  // Schedule the host-to-device upload. (hostUBO is copied into the cmd
  // buffer so it is okay to deallocate when the function returns).
  vkCmdUpdateBuffer(cmdBuf, m_bGlobals.buffer, 0, sizeof(GlobalUniforms), &hostUBO);

  // Making sure the updated UBO will be visible.
  VkBufferMemoryBarrier afterBarrier{VK_STRUCTURE_TYPE_BUFFER_MEMORY_BARRIER};
  afterBarrier.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
  afterBarrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
  afterBarrier.buffer        = deviceUBO;
  afterBarrier.offset        = 0;
  afterBarrier.size          = sizeof(hostUBO);
  vkCmdPipelineBarrier(cmdBuf, VK_PIPELINE_STAGE_TRANSFER_BIT, uboUsageStages, VK_DEPENDENCY_DEVICE_GROUP_BIT, 0,
                       nullptr, 1, &afterBarrier, 0, nullptr);
}

//--------------------------------------------------------------------------------------------------
// Describing the layout pushed when rendering
//
void HelloVulkan::createDescriptorSetLayout()
{
  auto nbTxt = static_cast<uint32_t>(m_textures.size());

  // Camera matrices
  m_descSetLayoutBind.addBinding(SceneBindings::eGlobals, VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 1,
                                 VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_RAYGEN_BIT_KHR);
  // Obj descriptions
  m_descSetLayoutBind.addBinding(SceneBindings::eObjDescs, VK_DESCRIPTOR_TYPE_STORAGE_BUFFER, 1,
                                 VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_FRAGMENT_BIT | VK_SHADER_STAGE_CLOSEST_HIT_BIT_KHR);
  // Textures
  m_descSetLayoutBind.addBinding(SceneBindings::eTextures, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, nbTxt,
                                 VK_SHADER_STAGE_FRAGMENT_BIT | VK_SHADER_STAGE_CLOSEST_HIT_BIT_KHR);

  // The top level acceleration structure
  m_descSetLayoutBind.addBinding(eTlas, VK_DESCRIPTOR_TYPE_ACCELERATION_STRUCTURE_KHR, 1, VK_SHADER_STAGE_FRAGMENT_BIT);

  m_descSetLayout = m_descSetLayoutBind.createLayout(m_device);
  m_descPool      = m_descSetLayoutBind.createPool(m_device, 1);
  m_descSet       = nvvk::allocateDescriptorSet(m_device, m_descPool, m_descSetLayout);
}

//--------------------------------------------------------------------------------------------------
// Setting up the buffers in the descriptor set
//
void HelloVulkan::updateDescriptorSet()
{
  std::vector<VkWriteDescriptorSet> writes;

  // Camera matrices and scene description
  VkDescriptorBufferInfo dbiUnif{m_bGlobals.buffer, 0, VK_WHOLE_SIZE};
  writes.emplace_back(m_descSetLayoutBind.makeWrite(m_descSet, SceneBindings::eGlobals, &dbiUnif));

  VkDescriptorBufferInfo dbiSceneDesc{m_bObjDesc.buffer, 0, VK_WHOLE_SIZE};
  writes.emplace_back(m_descSetLayoutBind.makeWrite(m_descSet, SceneBindings::eObjDescs, &dbiSceneDesc));

  // All texture samplers
  std::vector<VkDescriptorImageInfo> diit;
  for(auto& texture : m_textures)
  {
    diit.emplace_back(texture.descriptor);
  }
  writes.emplace_back(m_descSetLayoutBind.makeWriteArray(m_descSet, SceneBindings::eTextures, diit.data()));

  VkAccelerationStructureKHR                   tlas = m_rtBuilder.getAccelerationStructure();
  VkWriteDescriptorSetAccelerationStructureKHR descASInfo{VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET_ACCELERATION_STRUCTURE_KHR};
  descASInfo.accelerationStructureCount = 1;
  descASInfo.pAccelerationStructures    = &tlas;
  writes.emplace_back(m_descSetLayoutBind.makeWrite(m_descSet, eTlas, &descASInfo));


  // Writing the information
  vkUpdateDescriptorSets(m_device, static_cast<uint32_t>(writes.size()), writes.data(), 0, nullptr);
}


//--------------------------------------------------------------------------------------------------
// Creating the pipeline layout
//
void HelloVulkan::createGraphicsPipeline()
{
  VkPushConstantRange pushConstantRanges = {VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_FRAGMENT_BIT, 0, sizeof(PushConstantRaster)};

  // Creating the Pipeline Layout
  VkPipelineLayoutCreateInfo createInfo{VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO};
  createInfo.setLayoutCount         = 1;
  createInfo.pSetLayouts            = &m_descSetLayout;
  createInfo.pushConstantRangeCount = 1;
  createInfo.pPushConstantRanges    = &pushConstantRanges;
  vkCreatePipelineLayout(m_device, &createInfo, nullptr, &m_pipelineLayout);


  // Creating the Pipeline
  std::vector<std::string>                paths = defaultSearchPaths;
  nvvk::GraphicsPipelineGeneratorCombined gpb(m_device, m_pipelineLayout, m_offscreenRenderPass);
  gpb.depthStencilState.depthTestEnable = true;
  gpb.addShader(nvh::loadFile("spv/vert_shader.vert.spv", true, paths, true), VK_SHADER_STAGE_VERTEX_BIT);
  gpb.addShader(nvh::loadFile("spv/frag_shader.frag.spv", true, paths, true), VK_SHADER_STAGE_FRAGMENT_BIT);
  gpb.addBindingDescription({0, sizeof(VertexObj)});
  gpb.addAttributeDescriptions({
      {0, 0, VK_FORMAT_R32G32B32_SFLOAT, static_cast<uint32_t>(offsetof(VertexObj, pos))},
      {1, 0, VK_FORMAT_R32G32B32_SFLOAT, static_cast<uint32_t>(offsetof(VertexObj, nrm))},
      {2, 0, VK_FORMAT_R32G32B32_SFLOAT, static_cast<uint32_t>(offsetof(VertexObj, color))},
      {3, 0, VK_FORMAT_R32G32_SFLOAT, static_cast<uint32_t>(offsetof(VertexObj, texCoord))},
  });

  m_graphicsPipeline = gpb.createPipeline();
  m_debug.setObjectName(m_graphicsPipeline, "Graphics");
}

//--------------------------------------------------------------------------------------------------
// Loading the OBJ file and setting up all buffers
//
void HelloVulkan::loadModel(const std::string& filename, nvmath::mat4f transform)
{
  LOGI("Loading File:  %s \n", filename.c_str());
  ObjLoader loader;
  loader.loadModel(filename);

  // Converting from Srgb to linear
  for(auto& m : loader.m_materials)
  {
    m.ambient  = nvmath::pow(m.ambient, 2.2f);
    m.diffuse  = nvmath::pow(m.diffuse, 2.2f);
    m.specular = nvmath::pow(m.specular, 2.2f);
  }

  ObjModel model;
  model.nbIndices  = static_cast<uint32_t>(loader.m_indices.size());
  model.nbVertices = static_cast<uint32_t>(loader.m_vertices.size());

  // Create the buffers on Device and copy vertices, indices and materials
  nvvk::CommandPool  cmdBufGet(m_device, m_graphicsQueueIndex);
  VkCommandBuffer    cmdBuf          = cmdBufGet.createCommandBuffer();
  VkBufferUsageFlags flag            = VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT;
  VkBufferUsageFlags rayTracingFlags =  // used also for building acceleration structures
      flag | VK_BUFFER_USAGE_ACCELERATION_STRUCTURE_BUILD_INPUT_READ_ONLY_BIT_KHR | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT;
  model.vertexBuffer = m_alloc.createBuffer(cmdBuf, loader.m_vertices, VK_BUFFER_USAGE_VERTEX_BUFFER_BIT | rayTracingFlags);
  model.indexBuffer = m_alloc.createBuffer(cmdBuf, loader.m_indices, VK_BUFFER_USAGE_INDEX_BUFFER_BIT | rayTracingFlags);
  model.matColorBuffer = m_alloc.createBuffer(cmdBuf, loader.m_materials, VK_BUFFER_USAGE_STORAGE_BUFFER_BIT | flag);
  model.matIndexBuffer = m_alloc.createBuffer(cmdBuf, loader.m_matIndx, VK_BUFFER_USAGE_STORAGE_BUFFER_BIT | flag);
  // Creates all textures found and find the offset for this model
  auto txtOffset = static_cast<uint32_t>(m_textures.size());
  createTextureImages(cmdBuf, loader.m_textures);
  cmdBufGet.submitAndWait(cmdBuf);
  m_alloc.finalizeAndReleaseStaging();

  std::string objNb = std::to_string(m_objModel.size());
  m_debug.setObjectName(model.vertexBuffer.buffer, (std::string("vertex_" + objNb)));
  m_debug.setObjectName(model.indexBuffer.buffer, (std::string("index_" + objNb)));
  m_debug.setObjectName(model.matColorBuffer.buffer, (std::string("mat_" + objNb)));
  m_debug.setObjectName(model.matIndexBuffer.buffer, (std::string("matIdx_" + objNb)));

  // Keeping transformation matrix of the instance
  ObjInstance instance;
  instance.transform = transform;
  instance.objIndex  = static_cast<uint32_t>(m_objModel.size());
  m_instances.push_back(instance);

  // Creating information for device access
  ObjDesc desc;
  desc.txtOffset            = txtOffset;
  desc.vertexAddress        = nvvk::getBufferDeviceAddress(m_device, model.vertexBuffer.buffer);
  desc.indexAddress         = nvvk::getBufferDeviceAddress(m_device, model.indexBuffer.buffer);
  desc.materialAddress      = nvvk::getBufferDeviceAddress(m_device, model.matColorBuffer.buffer);
  desc.materialIndexAddress = nvvk::getBufferDeviceAddress(m_device, model.matIndexBuffer.buffer);

  // Keeping the obj host model and device description
  m_objModel.emplace_back(model);
  m_objDesc.emplace_back(desc);
}


//--------------------------------------------------------------------------------------------------
// Creating the uniform buffer holding the camera matrices
// - Buffer is host visible
//
void HelloVulkan::createUniformBuffer()
{
  m_bGlobals = m_alloc.createBuffer(sizeof(GlobalUniforms), VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT | VK_BUFFER_USAGE_TRANSFER_DST_BIT,
                                    VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
  m_debug.setObjectName(m_bGlobals.buffer, "Globals");
}

//--------------------------------------------------------------------------------------------------
// Create a storage buffer containing the description of the scene elements
// - Which geometry is used by which instance
// - Transformation
// - Offset for texture
//
void HelloVulkan::createObjDescriptionBuffer()
{
  nvvk::CommandPool cmdGen(m_device, m_graphicsQueueIndex);

  auto cmdBuf = cmdGen.createCommandBuffer();
  m_bObjDesc  = m_alloc.createBuffer(cmdBuf, m_objDesc, VK_BUFFER_USAGE_STORAGE_BUFFER_BIT);
  cmdGen.submitAndWait(cmdBuf);
  m_alloc.finalizeAndReleaseStaging();
  m_debug.setObjectName(m_bObjDesc.buffer, "ObjDescs");
}

//--------------------------------------------------------------------------------------------------
// Creating all textures and samplers
//
void HelloVulkan::createTextureImages(const VkCommandBuffer& cmdBuf, const std::vector<std::string>& textures)
{
  VkSamplerCreateInfo samplerCreateInfo{VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO};
  samplerCreateInfo.minFilter  = VK_FILTER_LINEAR;
  samplerCreateInfo.magFilter  = VK_FILTER_LINEAR;
  samplerCreateInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;
  samplerCreateInfo.maxLod     = FLT_MAX;

  VkFormat format = VK_FORMAT_R8G8B8A8_SRGB;

  // If no textures are present, create a dummy one to accommodate the pipeline layout
  if(textures.empty() && m_textures.empty())
  {
    nvvk::Texture texture;

    std::array<uint8_t, 4> color{255u, 255u, 255u, 255u};
    VkDeviceSize           bufferSize      = sizeof(color);
    auto                   imgSize         = VkExtent2D{1, 1};
    auto                   imageCreateInfo = nvvk::makeImage2DCreateInfo(imgSize, format);

    // Creating the dummy texture
    nvvk::Image           image  = m_alloc.createImage(cmdBuf, bufferSize, color.data(), imageCreateInfo);
    VkImageViewCreateInfo ivInfo = nvvk::makeImageViewCreateInfo(image.image, imageCreateInfo);
    texture                      = m_alloc.createTexture(image, ivInfo, samplerCreateInfo);

    // The image format must be in VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL
    nvvk::cmdBarrierImageLayout(cmdBuf, texture.image, VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);
    m_textures.push_back(texture);
  }
  else
  {
    // Uploading all images
    for(const auto& texture : textures)
    {
      std::stringstream o;
      int               texWidth, texHeight, texChannels;
      o << "media/textures/" << texture;
      std::string txtFile = nvh::findFile(o.str(), defaultSearchPaths, true);

      stbi_uc* stbi_pixels = stbi_load(txtFile.c_str(), &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);

      std::array<stbi_uc, 4> color{255u, 0u, 255u, 255u};

      stbi_uc* pixels = stbi_pixels;
      // Handle failure
      if(!stbi_pixels)
      {
        texWidth = texHeight = 1;
        texChannels          = 4;
        pixels               = reinterpret_cast<stbi_uc*>(color.data());
      }

      VkDeviceSize bufferSize      = static_cast<uint64_t>(texWidth) * texHeight * sizeof(uint8_t) * 4;
      auto         imgSize         = VkExtent2D{(uint32_t)texWidth, (uint32_t)texHeight};
      auto         imageCreateInfo = nvvk::makeImage2DCreateInfo(imgSize, format, VK_IMAGE_USAGE_SAMPLED_BIT, true);

      {
        nvvk::Image image = m_alloc.createImage(cmdBuf, bufferSize, pixels, imageCreateInfo);
        nvvk::cmdGenerateMipmaps(cmdBuf, image.image, format, imgSize, imageCreateInfo.mipLevels);
        VkImageViewCreateInfo ivInfo  = nvvk::makeImageViewCreateInfo(image.image, imageCreateInfo);
        nvvk::Texture         texture = m_alloc.createTexture(image, ivInfo, samplerCreateInfo);

        m_textures.push_back(texture);
      }

      stbi_image_free(stbi_pixels);
    }
  }
}

//--------------------------------------------------------------------------------------------------
// Destroying all allocations
//
void HelloVulkan::destroyResources()
{
  vkDestroyPipeline(m_device, m_graphicsPipeline, nullptr);
  vkDestroyPipelineLayout(m_device, m_pipelineLayout, nullptr);
  vkDestroyDescriptorPool(m_device, m_descPool, nullptr);
  vkDestroyDescriptorSetLayout(m_device, m_descSetLayout, nullptr);

  m_alloc.destroy(m_bGlobals);
  m_alloc.destroy(m_bObjDesc);

  for(auto& m : m_objModel)
  {
    m_alloc.destroy(m.vertexBuffer);
    m_alloc.destroy(m.indexBuffer);
    m_alloc.destroy(m.matColorBuffer);
    m_alloc.destroy(m.matIndexBuffer);
  }

  for(auto& t : m_textures)
  {
    m_alloc.destroy(t);
  }

  //#Post
  m_alloc.destroy(m_offscreenColor);
  m_alloc.destroy(m_offscreenDepth);
  vkDestroyPipeline(m_device, m_postPipeline, nullptr);
  vkDestroyPipelineLayout(m_device, m_postPipelineLayout, nullptr);
  vkDestroyDescriptorPool(m_device, m_postDescPool, nullptr);
  vkDestroyDescriptorSetLayout(m_device, m_postDescSetLayout, nullptr);
  vkDestroyRenderPass(m_device, m_offscreenRenderPass, nullptr);
  vkDestroyFramebuffer(m_device, m_offscreenFramebuffer, nullptr);


  // #VKRay
  m_rtBuilder.destroy();
  m_alloc.deinit();
}

//--------------------------------------------------------------------------------------------------
// Drawing the scene in raster mode
//
void HelloVulkan::rasterize(const VkCommandBuffer& cmdBuf)
{
  VkDeviceSize offset{0};

  m_debug.beginLabel(cmdBuf, "Rasterize");

  // Dynamic Viewport
  setViewport(cmdBuf);

  // Drawing all triangles
  vkCmdBindPipeline(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_graphicsPipeline);
  vkCmdBindDescriptorSets(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_pipelineLayout, 0, 1, &m_descSet, 0, nullptr);


  for(const HelloVulkan::ObjInstance& inst : m_instances)
  {
    auto& model            = m_objModel[inst.objIndex];
    m_pcRaster.objIndex    = inst.objIndex;  // Telling which object is drawn
    m_pcRaster.modelMatrix = inst.transform;

    vkCmdPushConstants(cmdBuf, m_pipelineLayout, VK_SHADER_STAGE_VERTEX_BIT | VK_SHADER_STAGE_FRAGMENT_BIT, 0,
                       sizeof(PushConstantRaster), &m_pcRaster);
    vkCmdBindVertexBuffers(cmdBuf, 0, 1, &model.vertexBuffer.buffer, &offset);
    vkCmdBindIndexBuffer(cmdBuf, model.indexBuffer.buffer, 0, VK_INDEX_TYPE_UINT32);
    vkCmdDrawIndexed(cmdBuf, model.nbIndices, 1, 0, 0, 0);
  }
  m_debug.endLabel(cmdBuf);
}

//--------------------------------------------------------------------------------------------------
// Handling resize of the window
//
void HelloVulkan::onResize(int /*w*/, int /*h*/)
{
  createOffscreenRender();
  updatePostDescriptorSet();
}


//////////////////////////////////////////////////////////////////////////
// Post-processing
//////////////////////////////////////////////////////////////////////////


//--------------------------------------------------------------------------------------------------
// Creating an offscreen frame buffer and the associated render pass
//
void HelloVulkan::createOffscreenRender()
{
  m_alloc.destroy(m_offscreenColor);
  m_alloc.destroy(m_offscreenDepth);

  // Creating the color image
  {
    auto colorCreateInfo = nvvk::makeImage2DCreateInfo(m_size, m_offscreenColorFormat,
                                                       VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT
                                                           | VK_IMAGE_USAGE_STORAGE_BIT);


    nvvk::Image           image  = m_alloc.createImage(colorCreateInfo);
    VkImageViewCreateInfo ivInfo = nvvk::makeImageViewCreateInfo(image.image, colorCreateInfo);
    VkSamplerCreateInfo   sampler{VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO};
    m_offscreenColor                        = m_alloc.createTexture(image, ivInfo, sampler);
    m_offscreenColor.descriptor.imageLayout = VK_IMAGE_LAYOUT_GENERAL;
  }

  // Creating the depth buffer
  auto depthCreateInfo = nvvk::makeImage2DCreateInfo(m_size, m_offscreenDepthFormat, VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT);
  {
    nvvk::Image image = m_alloc.createImage(depthCreateInfo);


    VkImageViewCreateInfo depthStencilView{VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO};
    depthStencilView.viewType         = VK_IMAGE_VIEW_TYPE_2D;
    depthStencilView.format           = m_offscreenDepthFormat;
    depthStencilView.subresourceRange = {VK_IMAGE_ASPECT_DEPTH_BIT, 0, 1, 0, 1};
    depthStencilView.image            = image.image;

    m_offscreenDepth = m_alloc.createTexture(image, depthStencilView);
  }

  // Setting the image layout for both color and depth
  {
    nvvk::CommandPool genCmdBuf(m_device, m_graphicsQueueIndex);
    auto              cmdBuf = genCmdBuf.createCommandBuffer();
    nvvk::cmdBarrierImageLayout(cmdBuf, m_offscreenColor.image, VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_GENERAL);
    nvvk::cmdBarrierImageLayout(cmdBuf, m_offscreenDepth.image, VK_IMAGE_LAYOUT_UNDEFINED,
                                VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL, VK_IMAGE_ASPECT_DEPTH_BIT);

    genCmdBuf.submitAndWait(cmdBuf);
  }

  // Creating a renderpass for the offscreen
  if(!m_offscreenRenderPass)
  {
    m_offscreenRenderPass = nvvk::createRenderPass(m_device, {m_offscreenColorFormat}, m_offscreenDepthFormat, 1, true,
                                                   true, VK_IMAGE_LAYOUT_GENERAL, VK_IMAGE_LAYOUT_GENERAL);
  }


  // Creating the frame buffer for offscreen
  std::vector<VkImageView> attachments = {m_offscreenColor.descriptor.imageView, m_offscreenDepth.descriptor.imageView};

  vkDestroyFramebuffer(m_device, m_offscreenFramebuffer, nullptr);
  VkFramebufferCreateInfo info{VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO};
  info.renderPass      = m_offscreenRenderPass;
  info.attachmentCount = 2;
  info.pAttachments    = attachments.data();
  info.width           = m_size.width;
  info.height          = m_size.height;
  info.layers          = 1;
  vkCreateFramebuffer(m_device, &info, nullptr, &m_offscreenFramebuffer);
}

//--------------------------------------------------------------------------------------------------
// The pipeline is how things are rendered, which shaders, type of primitives, depth test and more
//
void HelloVulkan::createPostPipeline()
{
  // Push constants in the fragment shader
  VkPushConstantRange pushConstantRanges = {VK_SHADER_STAGE_FRAGMENT_BIT, 0, sizeof(float)};

  // Creating the pipeline layout
  VkPipelineLayoutCreateInfo createInfo{VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO};
  createInfo.setLayoutCount         = 1;
  createInfo.pSetLayouts            = &m_postDescSetLayout;
  createInfo.pushConstantRangeCount = 1;
  createInfo.pPushConstantRanges    = &pushConstantRanges;
  vkCreatePipelineLayout(m_device, &createInfo, nullptr, &m_postPipelineLayout);


  // Pipeline: completely generic, no vertices
  nvvk::GraphicsPipelineGeneratorCombined pipelineGenerator(m_device, m_postPipelineLayout, m_renderPass);
  pipelineGenerator.addShader(nvh::loadFile("spv/passthrough.vert.spv", true, defaultSearchPaths, true), VK_SHADER_STAGE_VERTEX_BIT);
  pipelineGenerator.addShader(nvh::loadFile("spv/post.frag.spv", true, defaultSearchPaths, true), VK_SHADER_STAGE_FRAGMENT_BIT);
  pipelineGenerator.rasterizationState.cullMode = VK_CULL_MODE_NONE;
  m_postPipeline                                = pipelineGenerator.createPipeline();
  m_debug.setObjectName(m_postPipeline, "post");
}

//--------------------------------------------------------------------------------------------------
// The descriptor layout is the description of the data that is passed to the vertex or the
// fragment program.
//
void HelloVulkan::createPostDescriptor()
{
  m_postDescSetLayoutBind.addBinding(0, VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1, VK_SHADER_STAGE_FRAGMENT_BIT);
  m_postDescSetLayout = m_postDescSetLayoutBind.createLayout(m_device);
  m_postDescPool      = m_postDescSetLayoutBind.createPool(m_device);
  m_postDescSet       = nvvk::allocateDescriptorSet(m_device, m_postDescPool, m_postDescSetLayout);
}


//--------------------------------------------------------------------------------------------------
// Update the output
//
void HelloVulkan::updatePostDescriptorSet()
{
  VkWriteDescriptorSet writeDescriptorSets = m_postDescSetLayoutBind.makeWrite(m_postDescSet, 0, &m_offscreenColor.descriptor);
  vkUpdateDescriptorSets(m_device, 1, &writeDescriptorSets, 0, nullptr);
}

//--------------------------------------------------------------------------------------------------
// Draw a full screen quad with the attached image
//
void HelloVulkan::drawPost(VkCommandBuffer cmdBuf)
{
  m_debug.beginLabel(cmdBuf, "Post");

  setViewport(cmdBuf);

  auto aspectRatio = static_cast<float>(m_size.width) / static_cast<float>(m_size.height);
  vkCmdPushConstants(cmdBuf, m_postPipelineLayout, VK_SHADER_STAGE_FRAGMENT_BIT, 0, sizeof(float), &aspectRatio);
  vkCmdBindPipeline(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_postPipeline);
  vkCmdBindDescriptorSets(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_postPipelineLayout, 0, 1, &m_postDescSet, 0, nullptr);
  vkCmdDraw(cmdBuf, 3, 1, 0, 0);

  m_debug.endLabel(cmdBuf);
}

//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////

//--------------------------------------------------------------------------------------------------
// Initialize Vulkan ray tracing
// #VKRay
void HelloVulkan::initRayTracing()
{
  // Requesting ray tracing properties
  VkPhysicalDeviceProperties2 prop2{VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_PROPERTIES_2};
  prop2.pNext = &m_rtProperties;
  vkGetPhysicalDeviceProperties2(m_physicalDevice, &prop2);

  m_rtBuilder.setup(m_device, &m_alloc, m_graphicsQueueIndex);
}

//--------------------------------------------------------------------------------------------------
// Convert an OBJ model into the ray tracing geometry used to build the BLAS
//
auto HelloVulkan::objectToVkGeometryKHR(const ObjModel& model)
{
  // BLAS builder requires raw device addresses.
  VkDeviceAddress vertexAddress = nvvk::getBufferDeviceAddress(m_device, model.vertexBuffer.buffer);
  VkDeviceAddress indexAddress  = nvvk::getBufferDeviceAddress(m_device, model.indexBuffer.buffer);

  uint32_t maxPrimitiveCount = model.nbIndices / 3;

  // Describe buffer as array of VertexObj.
  VkAccelerationStructureGeometryTrianglesDataKHR triangles{VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_GEOMETRY_TRIANGLES_DATA_KHR};
  triangles.vertexFormat             = VK_FORMAT_R32G32B32_SFLOAT;  // vec3 vertex position data.
  triangles.vertexData.deviceAddress = vertexAddress;
  triangles.vertexStride             = sizeof(VertexObj);
  // Describe index data (32-bit unsigned int)
  triangles.indexType               = VK_INDEX_TYPE_UINT32;
  triangles.indexData.deviceAddress = indexAddress;
  // Indicate identity transform by setting transformData to null device pointer.
  //triangles.transformData = {};
  triangles.maxVertex = model.nbVertices;

  // Identify the above data as containing opaque triangles.
  VkAccelerationStructureGeometryKHR asGeom{VK_STRUCTURE_TYPE_ACCELERATION_STRUCTURE_GEOMETRY_KHR};
  asGeom.geometryType       = VK_GEOMETRY_TYPE_TRIANGLES_KHR;
  asGeom.flags              = VK_GEOMETRY_OPAQUE_BIT_KHR;
  asGeom.geometry.triangles = triangles;

  // The entire array will be used to build the BLAS.
  VkAccelerationStructureBuildRangeInfoKHR offset;
  offset.firstVertex     = 0;
  offset.primitiveCount  = maxPrimitiveCount;
  offset.primitiveOffset = 0;
  offset.transformOffset = 0;

  // Our blas is made from only one geometry, but could be made of many geometries
  nvvk::RaytracingBuilderKHR::BlasInput input;
  input.asGeometry.emplace_back(asGeom);
  input.asBuildOffsetInfo.emplace_back(offset);

  return input;
}

//--------------------------------------------------------------------------------------------------
//
//
void HelloVulkan::createBottomLevelAS()
{
  // BLAS - Storing each primitive in a geometry
  std::vector<nvvk::RaytracingBuilderKHR::BlasInput> allBlas;
  allBlas.reserve(m_objModel.size());
  for(const auto& obj : m_objModel)
  {
    auto blas = objectToVkGeometryKHR(obj);

    // We could add more geometry in each BLAS, but we add only one for now
    allBlas.emplace_back(blas);
  }
  m_rtBuilder.buildBlas(allBlas, VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_TRACE_BIT_KHR);
}

//--------------------------------------------------------------------------------------------------
//
//
void HelloVulkan::createTopLevelAS()
{
  std::vector<VkAccelerationStructureInstanceKHR> tlas;
  tlas.reserve(m_instances.size());
  for(const HelloVulkan::ObjInstance& inst : m_instances)
  {
    VkAccelerationStructureInstanceKHR rayInst{};
    rayInst.transform                      = nvvk::toTransformMatrixKHR(inst.transform);  // Position of the instance
    rayInst.instanceCustomIndex            = inst.objIndex;                               // gl_InstanceCustomIndexEXT
    rayInst.accelerationStructureReference = m_rtBuilder.getBlasDeviceAddress(inst.objIndex);
    rayInst.flags                          = VK_GEOMETRY_INSTANCE_TRIANGLE_FACING_CULL_DISABLE_BIT_KHR;
    rayInst.mask                           = 0xFF;       //  Only be hit if rayMask & instance.mask != 0
    rayInst.instanceShaderBindingTableRecordOffset = 0;  // We will use the same hit group for all objects
    tlas.emplace_back(rayInst);
  }
  m_rtBuilder.buildTlas(tlas, VK_BUILD_ACCELERATION_STRUCTURE_PREFER_FAST_TRACE_BIT_KHR);
}