// Copyright(c) 2019, 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.
//
// VulkanHpp Samples : RayTracing
//                     Simple sample how to ray trace using Vulkan

#include <numeric>
#include <random>
#include <sstream>

#include <vulkan/vulkan.hpp>
#include <GLFW/glfw3.h>

#define GLM_FORCE_DEPTH_ZERO_TO_ONE
#define GLM_FORCE_RADIANS
#define GLM_ENABLE_EXPERIMENTAL
#pragma warning(disable:4201)   // disable warning C4201: nonstandard extension used: nameless struct/union; needed to get glm/detail/type_vec?.hpp without warnings
#include <glm/glm.hpp>
#include <glm/gtc/matrix_inverse.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include "CameraManipulator.hpp"
#include "../utils/shaders.hpp"
#include "../utils/utils.hpp"
#include "SPIRV/GlslangToSpv.h"

static char const* AppName = "RayTracing";
static char const* EngineName = "Vulkan.hpp";

struct GeometryInstanceData
{
  GeometryInstanceData(glm::mat4x4 const& transform_, uint32_t instanceID_, uint8_t mask_, uint32_t instanceOffset_, uint8_t flags_, uint64_t accelerationStructureHandle_)
    : instanceId(instanceID_)
    , mask(mask_)
    , instanceOffset(instanceOffset_)
    , flags(flags_)
    , accelerationStructureHandle(accelerationStructureHandle_)
  {
    assert(!(instanceID_ & 0xFF000000) && !(instanceOffset_ & 0xFF000000));
    memcpy(transform, &transform_, 12 * sizeof(float));
  }

  float     transform[12];                // Transform matrix, containing only the top 3 rows
  uint32_t  instanceId     : 24;          // Instance index
  uint32_t  mask           :  8;          // Visibility mask
  uint32_t  instanceOffset : 24;          // Index of the hit group which will be invoked when a ray hits the instance
  uint32_t  flags          :  8;          // Instance flags, such as culling
  uint64_t  accelerationStructureHandle;  // Opaque handle of the bottom-level acceleration structure
};
static_assert(sizeof(GeometryInstanceData) == 64, "GeometryInstanceData structure compiles to incorrect size");

struct AccelerationStructureData
{
  vk::UniqueAccelerationStructureNV   acclerationStructure;
  std::unique_ptr<vk::su::BufferData> scratchBufferData;
  std::unique_ptr<vk::su::BufferData> resultBufferData;
  std::unique_ptr<vk::su::BufferData> instanceBufferData;
};

AccelerationStructureData createAccelerationStructureData(vk::PhysicalDevice const& physicalDevice, vk::UniqueDevice const& device, vk::UniqueCommandBuffer const& commandBuffer,
                                                          std::vector<std::pair<vk::AccelerationStructureNV, glm::mat4x4>> const& instances, std::vector<vk::GeometryNV> const& geometries)
{
  assert(instances.empty() ^ geometries.empty());

  AccelerationStructureData accelerationStructureData;

  vk::AccelerationStructureTypeNV accelerationStructureType = instances.empty() ? vk::AccelerationStructureTypeNV::eBottomLevel : vk::AccelerationStructureTypeNV::eTopLevel;
  vk::AccelerationStructureInfoNV accelerationStructureInfo(accelerationStructureType, {}, vk::su::checked_cast<uint32_t>(instances.size()),
                                                            vk::su::checked_cast<uint32_t>(geometries.size()), geometries.data());
  accelerationStructureData.acclerationStructure = device->createAccelerationStructureNVUnique(vk::AccelerationStructureCreateInfoNV(0, accelerationStructureInfo));

  vk::AccelerationStructureMemoryRequirementsInfoNV objectRequirements(vk::AccelerationStructureMemoryRequirementsTypeNV::eObject, *accelerationStructureData.acclerationStructure);
  vk::DeviceSize resultSizeInBytes = device->getAccelerationStructureMemoryRequirementsNV(objectRequirements).memoryRequirements.size;
  assert(0 < resultSizeInBytes);
  accelerationStructureData.resultBufferData = std::unique_ptr<vk::su::BufferData>(new vk::su::BufferData(physicalDevice, device, resultSizeInBytes, vk::BufferUsageFlagBits::eRayTracingNV,
                                                                                                          vk::MemoryPropertyFlagBits::eDeviceLocal));

  vk::AccelerationStructureMemoryRequirementsInfoNV buildScratchRequirements(vk::AccelerationStructureMemoryRequirementsTypeNV::eBuildScratch,
                                                                             *accelerationStructureData.acclerationStructure);
  vk::AccelerationStructureMemoryRequirementsInfoNV updateScratchRequirements(vk::AccelerationStructureMemoryRequirementsTypeNV::eUpdateScratch,
                                                                              *accelerationStructureData.acclerationStructure);
  vk::DeviceSize scratchSizeInBytes = 
    std::max(device->getAccelerationStructureMemoryRequirementsNV(buildScratchRequirements).memoryRequirements.size,
             device->getAccelerationStructureMemoryRequirementsNV(updateScratchRequirements).memoryRequirements.size);
  assert(0 < scratchSizeInBytes);

  accelerationStructureData.scratchBufferData = std::unique_ptr<vk::su::BufferData>(new vk::su::BufferData(physicalDevice, device, scratchSizeInBytes, vk::BufferUsageFlagBits::eRayTracingNV,
                                                                                                           vk::MemoryPropertyFlagBits::eDeviceLocal));

  if (!instances.empty())
  {
    accelerationStructureData.instanceBufferData = std::unique_ptr<vk::su::BufferData>(new vk::su::BufferData(physicalDevice, device, instances.size() * sizeof(GeometryInstanceData),
                                                                                                              vk::BufferUsageFlagBits::eRayTracingNV));

    std::vector<GeometryInstanceData> geometryInstanceData;
    for(size_t i = 0; i < instances.size(); i++)
    {
      uint64_t accelerationStructureHandle = 0;
      device->getAccelerationStructureHandleNV(instances[i].first, sizeof(uint64_t), &accelerationStructureHandle);

      // For each instance we set its instance index to its index i in the instance vector, and set
      // its hit group index to 2*i. The hit group index defines which entry of the shader binding
      // table will contain the hit group to be executed when hitting this instance. We set this
      // index to 2*i due to the use of 2 types of rays in the scene: the camera rays and the shadow
      // rays. For each instance, the SBT will then have 2 hit groups
      geometryInstanceData.push_back(GeometryInstanceData(glm::transpose(instances[i].second), static_cast<uint32_t>(i), 0xFF, static_cast<uint32_t>(2 * i),
                                                          static_cast<uint8_t>(vk::GeometryInstanceFlagBitsNV::eTriangleCullDisable), accelerationStructureHandle));
    }
    accelerationStructureData.instanceBufferData->upload(device, geometryInstanceData);
  }

  device->bindAccelerationStructureMemoryNV(vk::BindAccelerationStructureMemoryInfoNV(*accelerationStructureData.acclerationStructure,
                                                                                      *accelerationStructureData.resultBufferData->deviceMemory));

  commandBuffer->buildAccelerationStructureNV(vk::AccelerationStructureInfoNV(accelerationStructureType, {}, vk::su::checked_cast<uint32_t>(instances.size()),
                                                                              vk::su::checked_cast<uint32_t>(geometries.size()), geometries.data()),
                                              accelerationStructureData.instanceBufferData ? *accelerationStructureData.instanceBufferData->buffer : nullptr, 0, false,
                                              *accelerationStructureData.acclerationStructure, nullptr, *accelerationStructureData.scratchBufferData->buffer, 0);

  commandBuffer->pipelineBarrier(vk::PipelineStageFlagBits::eAccelerationStructureBuildNV, vk::PipelineStageFlagBits::eAccelerationStructureBuildNV, {},
                                 vk::MemoryBarrier(vk::AccessFlagBits::eAccelerationStructureWriteNV | vk::AccessFlagBits::eAccelerationStructureReadNV,
                                                   vk::AccessFlagBits::eAccelerationStructureWriteNV | vk::AccessFlagBits::eAccelerationStructureReadNV), {}, {});

  return accelerationStructureData;
}

struct PerFrameData
{
  vk::UniqueCommandPool   commandPool;
  vk::UniqueCommandBuffer commandBuffer;
  vk::UniqueFence         fence;
  vk::UniqueSemaphore     presentCompleteSemaphore;
  vk::UniqueSemaphore     renderCompleteSemaphore;
};

struct UniformBufferObject
{
  glm::mat4 model;
  glm::mat4 view;
  glm::mat4 proj;
  glm::mat4 modelIT;
  glm::mat4 viewInverse;
  glm::mat4 projInverse;
};

struct Material
{
  glm::vec3 diffuse = glm::vec3(0.7f, 0.7f, 0.7f);
  int textureID     = -1;
};
const size_t MaterialStride = ((sizeof(Material) + 15) / 16) * 16;

struct Vertex
{
  Vertex(glm::vec3 const& p, glm::vec3 const& n, glm::vec2 const& tc, int m = 0)
    : pos(p)
    , nrm(n)
    , texCoord(tc)
    , matID(m)
  {}

  glm::vec3 pos;
  glm::vec3 nrm;
  glm::vec2 texCoord;
  int       matID;
};
const size_t VertexStride = ((sizeof(Vertex) + 15) / 16) * 16;

static const std::vector<Vertex> cubeData =
{
  //        pos                               nrm                             texcoord              matID
  //  front face
  { Vertex(glm::vec3(-1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f,  0.0f,  1.0f),  glm::vec2(0.0f, 0.0f),   0) },
  //  back face
  { Vertex(glm::vec3( 1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f,  0.0f, -1.0f),  glm::vec2(0.0f, 0.0f),   0) },
  //  left face
  { Vertex(glm::vec3(-1.0f, -1.0f, -1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f,  1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f,  1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f,  1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f, -1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f, -1.0f),   glm::vec3(-1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  //  right face
  { Vertex(glm::vec3( 1.0f, -1.0f,  1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f, -1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f, -1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f, -1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f,  1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f,  1.0f),   glm::vec3( 1.0f,  0.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  //  top face
  { Vertex(glm::vec3(-1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f, -1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f,  1.0f,  1.0f),   glm::vec3( 0.0f,  1.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  //  bottom face
  { Vertex(glm::vec3(-1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(1.0f, 0.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3( 1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(1.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f,  1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(0.0f, 1.0f),   0) },
  { Vertex(glm::vec3(-1.0f, -1.0f, -1.0f),   glm::vec3( 0.0f, -1.0f,  0.0f),  glm::vec2(0.0f, 0.0f),   0) },
};

static std::string vertexShaderText = R"(
#version 450

#extension GL_ARB_separate_shader_objects : enable

layout(binding = 0) uniform UniformBufferObject
{
  mat4 model;
  mat4 view;
  mat4 proj;
  mat4 modelIT;
} ubo;

layout(location = 0) in vec3 inPosition;
layout(location = 1) in vec3 inNormal;
layout(location = 2) in vec2 inTexCoord;
layout(location = 3) in int  inMatID;

layout(location = 0) flat out int  outMatID;
layout(location = 1)      out vec2 outTexCoord;
layout(location = 2)      out vec3 outNormal;

out gl_PerVertex
{
  vec4 gl_Position;
};

void main()
{
  gl_Position = ubo.proj * ubo.view * ubo.model * vec4(inPosition, 1.0);
  outMatID    = inMatID;
  outTexCoord = inTexCoord;
  outNormal   = vec3(ubo.modelIT * vec4(inNormal, 0.0));
}
)";

static std::string fragmentShaderText = R"(
#version 450

#extension GL_ARB_separate_shader_objects : enable
#extension GL_EXT_nonuniform_qualifier : enable

layout(location = 0) flat in int  matIndex;
layout(location = 1)      in vec2 texCoord;
layout(location = 2)      in vec3 normal;

struct Material
{
  vec3 diffuse;
  int  textureID;
};
const int sizeofMat = 1;

layout(binding = 1) buffer MaterialBufferObject { vec4[] m; } materials;
layout(binding = 2) uniform sampler2D[] textureSamplers;

Material unpackMaterial()
{
  Material m;
  vec4 d0 = materials.m[sizeofMat * matIndex + 0];

  m.diffuse = d0.xyz;
  m.textureID = floatBitsToInt(d0.w);

  return m;
}

layout(location = 0) out vec4 outColor;

void main()
{
  vec3 lightVector = normalize(vec3(5, 4, 3));

  float dot_product = max(dot(lightVector, normalize(normal)), 0.2);

  Material m = unpackMaterial();
  vec3 c = m.diffuse;
  if (0 <= m.textureID)
  {
    c *= texture(textureSamplers[m.textureID], texCoord).xyz;
  }
  c *= dot_product;

  outColor = vec4(c, 1);
}
)";

static std::string raygenShaderText = R"(
#version 460

#extension GL_NV_ray_tracing : require

layout(binding = 0, set = 0) uniform accelerationStructureNV topLevelAS;
layout(binding = 1, set = 0, rgba8) uniform image2D image;

layout(binding=2, set = 0) uniform UniformBufferObject
{
  mat4 model;
  mat4 view;
  mat4 proj;
  mat4 modelIT;
  mat4 viewInverse;
  mat4 projInverse;
} cam;

layout(location = 0) rayPayloadNV vec3 hitValue;

void main() 
{
  const vec2 pixelCenter = vec2(gl_LaunchIDNV.xy) + vec2(0.5);
  const vec2 inUV = pixelCenter/vec2(gl_LaunchSizeNV.xy);
  vec2 d = inUV * 2.0 - 1.0;

  vec4 origin = cam.viewInverse*vec4(0,0,0,1);
  vec4 target = cam.projInverse * vec4(d.x, d.y, 1, 1) ;
  vec4 direction = cam.viewInverse*vec4(normalize(target.xyz), 0) ;

  uint rayFlags = gl_RayFlagsOpaqueNV;
  uint cullMask = 0xff;
  float tmin = 0.001;
  float tmax = 10000.0;

  traceNV(topLevelAS, rayFlags, cullMask, 0 /*sbtRecordOffset*/, 0 /*sbtRecordStride*/, 0 /*missIndex*/, origin.xyz, tmin, direction.xyz, tmax, 0 /*payload*/);
  imageStore(image, ivec2(gl_LaunchIDNV.xy), vec4(hitValue, 0.0));
}
)";

static std::string missShaderText = R"(
#version 460

#extension GL_NV_ray_tracing : require

layout(location = 0) rayPayloadInNV vec3 hitValue;

void main()
{
  hitValue = vec3(0.0, 0.1, 0.3);
}
)";

static std::string shadowMissShaderText = R"(
#version 460

#extension GL_NV_ray_tracing : require

layout(location = 2) rayPayloadInNV bool isShadowed;

void main()
{
  isShadowed = false;
})";

static std::string closestHitShaderText = R"(
#version 460

#extension GL_NV_ray_tracing : require
#extension GL_EXT_nonuniform_qualifier : enable

layout(location = 0) rayPayloadInNV vec3 hitValue;
layout(location = 2) rayPayloadNV bool isShadowed;

hitAttributeNV vec3 attribs;
layout(binding = 0, set = 0) uniform accelerationStructureNV topLevelAS;

layout(binding = 3, set = 0) buffer Vertices { vec4 v[]; } vertices;
layout(binding = 4, set = 0) buffer Indices { uint i[]; } indices;

layout(binding = 5, set = 0) buffer MatColorBufferObject { vec4[] m; } materials;
layout(binding = 6, set = 0) uniform sampler2D[] textureSamplers;

struct Vertex
{
  vec3 pos;
  vec3 nrm;
  vec2 texCoord;
  int matIndex;
};
// Number of vec4 values used to represent a vertex
uint vertexSize = 3;

Vertex unpackVertex(uint index)
{
  Vertex v;

  vec4 d0 = vertices.v[vertexSize * index + 0];
  vec4 d1 = vertices.v[vertexSize * index + 1];
  vec4 d2 = vertices.v[vertexSize * index + 2];

  v.pos = d0.xyz;
  v.nrm = vec3(d0.w, d1.xy);
  v.texCoord = d1.zw;
  v.matIndex = floatBitsToInt(d2.x);
  return v;
}

struct Material
{
  vec3 diffuse;
  int textureID;
};
// Number of vec4 values used to represent a material
const int sizeofMat = 1;

Material unpackMaterial(int matIndex)
{
  Material m;
  vec4 d0 = materials.m[sizeofMat * matIndex + 0];

  m.diffuse = d0.xyz;
  m.textureID = floatBitsToInt(d0.w);
  return m;
}

void main()
{
  ivec3 ind = ivec3(indices.i[3 * gl_PrimitiveID], indices.i[3 * gl_PrimitiveID + 1], indices.i[3 * gl_PrimitiveID + 2]);

  Vertex v0 = unpackVertex(ind.x);
  Vertex v1 = unpackVertex(ind.y);
  Vertex v2 = unpackVertex(ind.z);

  const vec3 barycentrics = vec3(1.0 - attribs.x - attribs.y, attribs.x, attribs.y);

  vec3 normal = normalize(v0.nrm * barycentrics.x + v1.nrm * barycentrics.y + v2.nrm * barycentrics.z);

  vec3 lightVector = normalize(vec3(5, 4, 3));

  float dot_product = max(dot(lightVector, normal), 0.2);

  Material mat = unpackMaterial(v1.matIndex);

  vec3 c = dot_product * mat.diffuse; 
  if (0 <= mat.textureID)
  {
    vec2 texCoord = v0.texCoord * barycentrics.x + v1.texCoord * barycentrics.y + v2.texCoord * barycentrics.z;
    c *= texture(textureSamplers[mat.textureID], texCoord).xyz;
  }
  float tmin = 0.001;
  float tmax = 100.0;
  vec3 origin = gl_WorldRayOriginNV + gl_WorldRayDirectionNV * gl_HitTNV;
  isShadowed = true;
  traceNV(topLevelAS, gl_RayFlagsTerminateOnFirstHitNV|gl_RayFlagsOpaqueNV|gl_RayFlagsSkipClosestHitShaderNV,  0xFF, 1 /* sbtRecordOffset */, 0 /* sbtRecordStride */, 1 /* missIndex */, origin,
          tmin, lightVector, tmax, 2 /*payload location*/);
  hitValue = c;
  if (isShadowed)
  {
    hitValue *= 0.3f;
  }
}
)";

#ifndef IMGUI_VK_QUEUED_FRAMES
#define IMGUI_VK_QUEUED_FRAMES 2
#endif  // !IMGUI_VK_QUEUED_FRAMES

struct AppInfo
{
  vk::su::CameraManipulator cameraManipulator;
  bool                      useRasterRender     = false;
};

static void check_vk_result(VkResult err)
{
  if (err != 0)
  {
    std::cerr << AppName << ": Vulkan error " << vk::to_string(static_cast<vk::Result>(err));
    if (err < 0)
    {
      abort();
    }
  }
}

static void cursorPosCallback(GLFWwindow* window, double mouseX, double mouseY)
{
  vk::su::CameraManipulator::MouseButton mouseButton = (glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) == GLFW_PRESS)
                                                      ? vk::su::CameraManipulator::MouseButton::Left
                                                      : (glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_MIDDLE) == GLFW_PRESS)
                                                        ? vk::su::CameraManipulator::MouseButton::Middle
                                                        : (glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) == GLFW_PRESS)
                                                          ? vk::su::CameraManipulator::MouseButton::Right
                                                          : vk::su::CameraManipulator::MouseButton::None;
  if (mouseButton != vk::su::CameraManipulator::MouseButton::None)
  {
    vk::su::CameraManipulator::ModifierFlags modifiers;
    if (glfwGetKey(window, GLFW_KEY_LEFT_ALT) == GLFW_PRESS)
    {
      modifiers |= vk::su::CameraManipulator::ModifierFlagBits::Alt;
    }
    if (glfwGetKey(window, GLFW_KEY_LEFT_CONTROL) == GLFW_PRESS)
    {
      modifiers |= vk::su::CameraManipulator::ModifierFlagBits::Ctrl;
    }
    if (glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS)
    {
      modifiers |= vk::su::CameraManipulator::ModifierFlagBits::Shift;
    }

    vk::su::CameraManipulator & cameraManipulator = reinterpret_cast<AppInfo*>(glfwGetWindowUserPointer(window))->cameraManipulator;
    cameraManipulator.mouseMove(glm::ivec2(static_cast<int>(mouseX), static_cast<int>(mouseY)), mouseButton, modifiers);
  }
}

static void errorCallback(int error, const char* description)
{
  fprintf(stderr, "GLFW Error %d: %s\n", error, description);
}

static void framebufferSizeCallback(GLFWwindow* window, int w, int h)
{
  vk::su::CameraManipulator & cameraManipulator = reinterpret_cast<AppInfo*>(glfwGetWindowUserPointer(window))->cameraManipulator;
  cameraManipulator.setWindowSize(glm::ivec2(w, h));
}

static void keyCallback(GLFWwindow* window, int key, int /*scancode*/, int action, int /*mods*/)
{
  if (action == GLFW_PRESS)
  {
    switch (key)
    {
      case GLFW_KEY_ESCAPE:
      case 'Q':
        glfwSetWindowShouldClose(window, 1);
        break;
      case 'R':
      {
        AppInfo * appInfo = reinterpret_cast<AppInfo*>(glfwGetWindowUserPointer(window));
        appInfo->useRasterRender = !appInfo->useRasterRender;
      }
      break;
    }
  }
}

static void mouseButtonCallback(GLFWwindow* window, int /*button*/, int /*action*/, int /*mods*/)
{
  double xpos, ypos;
  glfwGetCursorPos(window, &xpos, &ypos);

  vk::su::CameraManipulator & cameraManipulator = reinterpret_cast<AppInfo*>(glfwGetWindowUserPointer(window))->cameraManipulator;
  cameraManipulator.setMousePosition(glm::ivec2(static_cast<int>(xpos), static_cast<int>(ypos)));
}

static void scrollCallback(GLFWwindow* window, double /*xoffset*/, double yoffset)
{
  vk::su::CameraManipulator & cameraManipulator = reinterpret_cast<AppInfo*>(glfwGetWindowUserPointer(window))->cameraManipulator;
  cameraManipulator.wheel(static_cast<int>(yoffset));
}


// random data and functions
static std::random_device randomDevice;
static std::mt19937 randomGenerator(randomDevice());

template <typename T>
T random(T minValue = std::numeric_limits<T>::min(), T maxValue = std::numeric_limits<T>::max())
{
  static_assert(std::numeric_limits<T>::is_integer, "Type T needs to be an integral type!\n");
  std::uniform_int_distribution<> randomDistribution(minValue, maxValue);

  return static_cast<T>(randomDistribution(randomGenerator));
}

glm::vec3 randomVec3(float minValue, float maxValue)
{
  std::uniform_real_distribution<float> randomDistribution(minValue, maxValue);

  return glm::vec3(randomDistribution(randomGenerator), randomDistribution(randomGenerator), randomDistribution(randomGenerator));
}

int main(int /*argc*/, char** /*argv*/)
{
  // number of cubes in x-, y-, and z-direction
  const size_t xMax = 10;
  const size_t yMax = 10;
  const size_t zMax = 10;

  AppInfo appInfo;

  try
  {
    // Setup glfw
    glfwSetErrorCallback(errorCallback);
    if (!glfwInit())
    {
      std::cerr << AppName << ": can't initialize glfw!\n";
      return 1;
    }
    if (!glfwVulkanSupported())
    {
      std::cerr << AppName << ": Vulkan not supported!\n";
      return 1;
    }

    // create a window using glfw
    glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
    vk::Extent2D windowExtent(1280, 720);
    GLFWwindow* window = glfwCreateWindow(windowExtent.width, windowExtent.height, AppName, nullptr, nullptr);

    // install some callbacks
    glfwSetCursorPosCallback(window, cursorPosCallback);
    glfwSetFramebufferSizeCallback(window, framebufferSizeCallback);
    glfwSetKeyCallback(window, keyCallback);
    glfwSetMouseButtonCallback(window, mouseButtonCallback);
    glfwSetScrollCallback(window, scrollCallback);

    // Setup camera and make it available as the userPointer in the glfw window
    appInfo.cameraManipulator.setWindowSize(glm::u32vec2(windowExtent.width, windowExtent.height));
    glm::vec3 diagonal = 3.0f * glm::vec3(static_cast<float>(xMax), static_cast<float>(yMax), static_cast<float>(zMax));
    appInfo.cameraManipulator.setLookat(1.5f * diagonal, 0.5f *diagonal, glm::vec3(0, 1, 0));
    glfwSetWindowUserPointer(window, &appInfo);

    // Create Vulkan Instance with needed extensions
    uint32_t glfwExtensionsCount;
    const char** glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionsCount);
    std::vector<std::string> instanceExtensions;
    instanceExtensions.reserve(glfwExtensionsCount + 1);
    for (uint32_t i = 0; i < glfwExtensionsCount; i++)
    {
      instanceExtensions.push_back(glfwExtensions[i]);
    }
    instanceExtensions.push_back(VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME);

    vk::UniqueInstance instance = vk::su::createInstance(AppName, EngineName, {}, instanceExtensions);
#if !defined(NDEBUG)
    vk::UniqueDebugUtilsMessengerEXT debugUtilsMessenger = vk::su::createDebugUtilsMessenger(instance);
#endif

    vk::PhysicalDevice physicalDevice = instance->enumeratePhysicalDevices().front();

    // Create Window Surface (using glfw)
    vk::SurfaceKHR surface;
    VkResult err = glfwCreateWindowSurface(*instance, window, nullptr, reinterpret_cast<VkSurfaceKHR*>(&surface));
    check_vk_result(err);

    std::pair<uint32_t, uint32_t> graphicsAndPresentQueueFamilyIndex = vk::su::findGraphicsAndPresentQueueFamilyIndex(physicalDevice, surface);

    // Create a Device with ray tracing support (besides some other extensions needed) and needed features
    auto supportedFeatures = physicalDevice.getFeatures2<vk::PhysicalDeviceFeatures2, vk::PhysicalDeviceDescriptorIndexingFeaturesEXT>();
    vk::UniqueDevice device = vk::su::createDevice(physicalDevice, graphicsAndPresentQueueFamilyIndex.first,
                                                   {VK_KHR_SWAPCHAIN_EXTENSION_NAME, VK_NV_RAY_TRACING_EXTENSION_NAME, VK_KHR_GET_MEMORY_REQUIREMENTS_2_EXTENSION_NAME},
                                                   &supportedFeatures.get<vk::PhysicalDeviceFeatures2>().features, &supportedFeatures.get<vk::PhysicalDeviceDescriptorIndexingFeaturesEXT>());

    // setup stuff per frame
    std::array<PerFrameData, IMGUI_VK_QUEUED_FRAMES> perFrameData;
    for (int i = 0; i < IMGUI_VK_QUEUED_FRAMES; i++)
    {
      perFrameData[i].commandPool = device->createCommandPoolUnique(vk::CommandPoolCreateInfo(vk::CommandPoolCreateFlagBits::eResetCommandBuffer, graphicsAndPresentQueueFamilyIndex.first));
      perFrameData[i].commandBuffer = std::move(device->allocateCommandBuffersUnique(vk::CommandBufferAllocateInfo(*perFrameData[i].commandPool, vk::CommandBufferLevel::ePrimary, 1)).front());
      perFrameData[i].fence = device->createFenceUnique(vk::FenceCreateInfo(vk::FenceCreateFlagBits::eSignaled));
      perFrameData[i].presentCompleteSemaphore = device->createSemaphoreUnique(vk::SemaphoreCreateInfo());
      perFrameData[i].renderCompleteSemaphore = device->createSemaphoreUnique(vk::SemaphoreCreateInfo());
    }

    vk::Queue graphicsQueue = device->getQueue(graphicsAndPresentQueueFamilyIndex.first, 0);
    vk::Queue presentQueue = device->getQueue(graphicsAndPresentQueueFamilyIndex.second, 0);

    // create a descriptor pool with a number of available descriptors
    std::vector<vk::DescriptorPoolSize> poolSizes =
    {
      { vk::DescriptorType::eCombinedImageSampler, 1000 },
      { vk::DescriptorType::eUniformBuffer, 1000},
      { vk::DescriptorType::eStorageBuffer, 1000 },
    };
    vk::UniqueDescriptorPool descriptorPool = vk::su::createDescriptorPool(device, poolSizes);

    // setup swap chain, render pass, depth buffer and the frame buffers
    vk::su::SwapChainData swapChainData(physicalDevice, device, surface, windowExtent, vk::ImageUsageFlagBits::eColorAttachment | vk::ImageUsageFlagBits::eStorage, vk::UniqueSwapchainKHR(),
                                        graphicsAndPresentQueueFamilyIndex.first, graphicsAndPresentQueueFamilyIndex.second);
    vk::SurfaceFormatKHR surfaceFormat = vk::su::pickSurfaceFormat(physicalDevice.getSurfaceFormatsKHR(surface));
    vk::Format depthFormat = vk::su::pickDepthFormat(physicalDevice);

    // setup a render pass
    vk::UniqueRenderPass renderPass = vk::su::createRenderPass(device, surfaceFormat.format, depthFormat);

    vk::su::DepthBufferData depthBufferData(physicalDevice, device, depthFormat, windowExtent);
    std::vector<vk::UniqueFramebuffer> framebuffers = vk::su::createFramebuffers(device, renderPass, swapChainData.imageViews, depthBufferData.imageView, windowExtent);

    bool samplerAnisotropy = supportedFeatures.get<vk::PhysicalDeviceFeatures2>().features.samplerAnisotropy;

    // create some simple checkerboard textures, randomly sized and colored
    const size_t textureCount = 10;
    std::vector<vk::su::TextureData> textures;
    textures.reserve(textureCount);
    for (size_t i = 0; i < textureCount; i++)
    {
      textures.push_back(vk::su::TextureData(physicalDevice, device, {random<uint32_t>(2, 8) * 16, random<uint32_t>(2, 8) * 16},
                                             vk::ImageUsageFlagBits::eTransferDst | vk::ImageUsageFlagBits::eSampled, {}, samplerAnisotropy, true));
    }
    vk::su::oneTimeSubmit(device, perFrameData[0].commandPool, graphicsQueue,
                          [&](vk::UniqueCommandBuffer const& commandBuffer)
                          {
                            for (auto & t : textures)
                            {
                              t.setImage(device, commandBuffer, vk::su::CheckerboardImageGenerator({random<uint8_t>(), random<uint8_t>(), random<uint8_t>()},
                                                                                                   {random<uint8_t>(), random<uint8_t>(), random<uint8_t>()}));
                            }
                          });

    // create some materials with a random diffuse color, referencing one of the above textures
    const size_t materialCount = 10;
    assert(materialCount == textureCount);
    std::vector<Material> materials(materialCount);
    for (size_t i = 0; i < materialCount; i++)
    {
      materials[i].diffuse = randomVec3(0.0f, 1.0f);
      materials[i].textureID = vk::su::checked_cast<uint32_t>(i);
    }
    vk::su::BufferData materialBufferData(physicalDevice, device, materialCount * MaterialStride, vk::BufferUsageFlagBits::eStorageBuffer);
    materialBufferData.upload(device, materials, MaterialStride);

    // create a a 3D-array of cubes, randomly jittered, using a random material
    std::vector<Vertex> vertices;
    vertices.reserve(xMax * yMax * zMax * cubeData.size());
    for (size_t x = 0; x < xMax; x++)
    {
      for (size_t y = 0; y < yMax; y++)
      {
        for (size_t z = 0; z < zMax; z++)
        {
          int m = random<int>(0, materialCount - 1);
          glm::vec3 jitter = randomVec3(0.0f, 0.6f);
          for (auto const& v : cubeData)
          {
            vertices.push_back(v);
            vertices.back().pos += 3.0f * glm::vec3(static_cast<float>(x), static_cast<float>(y), static_cast<float>(z)) + jitter;
            vertices.back().matID = static_cast<int>(m);
          }
        }
      }
    }

    // create an 1-1 index buffer
    std::vector<unsigned int> indices(vertices.size());
    std::iota(indices.begin(), indices.end(), 0);

    // there's just one vertex- and one index-buffer, but with more complex scene loaders there might be more!
    vk::su::BufferData  vertexBufferData(physicalDevice, device, vertices.size() * VertexStride,
                                         vk::BufferUsageFlagBits::eTransferDst | vk::BufferUsageFlagBits::eVertexBuffer | vk::BufferUsageFlagBits::eStorageBuffer,
                                         vk::MemoryPropertyFlagBits::eDeviceLocal);
    vertexBufferData.upload(physicalDevice, device, perFrameData[0].commandPool, graphicsQueue, vertices, VertexStride);

    vk::su::BufferData  indexBufferData(physicalDevice, device, indices.size() * sizeof(uint32_t),
                                        vk::BufferUsageFlagBits::eTransferDst | vk::BufferUsageFlagBits::eIndexBuffer | vk::BufferUsageFlagBits::eStorageBuffer,
                                        vk::MemoryPropertyFlagBits::eDeviceLocal);
    indexBufferData.upload(physicalDevice, device, perFrameData[0].commandPool, graphicsQueue, indices, sizeof(uint32_t));

    glm::mat4x4 transform(glm::mat4x4(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f));

    vk::UniqueDescriptorSetLayout descriptorSetLayout =
      vk::su::createDescriptorSetLayout(device,
                                        {
                                          { vk::DescriptorType::eUniformBuffer, 1, vk::ShaderStageFlagBits::eVertex },
                                          { vk::DescriptorType::eStorageBuffer, 1, vk::ShaderStageFlagBits::eVertex | vk::ShaderStageFlagBits::eFragment },
                                          { vk::DescriptorType::eCombinedImageSampler, static_cast<uint32_t>(textures.size()), vk::ShaderStageFlagBits::eFragment }
                                        });
    vk::UniquePipelineLayout pipelineLayout = device->createPipelineLayoutUnique(vk::PipelineLayoutCreateInfo({}, 1, &(*descriptorSetLayout)));

    glslang::InitializeProcess();
    vk::UniqueShaderModule vertexShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eVertex, vertexShaderText);
    vk::UniqueShaderModule fragmentShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eFragment, fragmentShaderText);
    glslang::FinalizeProcess();

    vk::UniquePipeline graphicsPipeline = vk::su::createGraphicsPipeline(device, vk::UniquePipelineCache(), std::make_pair(*vertexShaderModule, nullptr),
                                                                         std::make_pair(*fragmentShaderModule, nullptr), VertexStride,
                                                                         {
                                                                           { vk::Format::eR32G32B32Sfloat, vk::su::checked_cast<uint32_t>(offsetof(Vertex, pos)) },
                                                                           { vk::Format::eR32G32B32Sfloat, vk::su::checked_cast<uint32_t>(offsetof(Vertex, nrm)) },
                                                                           { vk::Format::eR32G32Sfloat, vk::su::checked_cast<uint32_t>(offsetof(Vertex, texCoord)) },
                                                                           { vk::Format::eR32Sint, vk::su::checked_cast<uint32_t>(offsetof(Vertex, matID)) }
                                                                         }, vk::FrontFace::eCounterClockwise, true, pipelineLayout, renderPass);

    vk::su::BufferData uniformBufferData(physicalDevice, device, sizeof(UniformBufferObject), vk::BufferUsageFlagBits::eUniformBuffer);

    vk::UniqueDescriptorSet descriptorSet = std::move(device->allocateDescriptorSetsUnique(vk::DescriptorSetAllocateInfo(*descriptorPool, 1, &*descriptorSetLayout)).front());
    vk::su::updateDescriptorSets(device, descriptorSet, { { vk::DescriptorType::eUniformBuffer, uniformBufferData.buffer, vk::UniqueBufferView() },
                                                          { vk::DescriptorType::eStorageBuffer, materialBufferData.buffer, vk::UniqueBufferView() } }, textures);

    // RayTracing specific stuff

    // create acceleration structures: one top-level, and just one bottom-level
    AccelerationStructureData topLevelAS, bottomLevelAS;
    vk::su::oneTimeSubmit(device, perFrameData[0].commandPool, graphicsQueue,
                          [&](vk::UniqueCommandBuffer const& commandBuffer)
                          {
                            vk::GeometryDataNV geometryDataNV(vk::GeometryTrianglesNV(*vertexBufferData.buffer, 0, vk::su::checked_cast<uint32_t>(vertices.size()), VertexStride,
                                                                                      vk::Format::eR32G32B32Sfloat, *indexBufferData.buffer, 0,
                                                                                      vk::su::checked_cast<uint32_t>(indices.size()), vk::IndexType::eUint32), {});
                            bottomLevelAS = createAccelerationStructureData(physicalDevice, device, commandBuffer, {}, {vk::GeometryNV(vk::GeometryTypeNV::eTriangles, geometryDataNV)});

                            topLevelAS = createAccelerationStructureData(physicalDevice, device, commandBuffer, {std::make_pair(*bottomLevelAS.acclerationStructure, transform)},
                                                                         std::vector<vk::GeometryNV>());
                          });

    // create raytracing descriptor set
    vk::su::oneTimeSubmit(device, perFrameData[0].commandPool, graphicsQueue,
                          [&](vk::UniqueCommandBuffer const& commandBuffer)
                          {
                            vk::BufferMemoryBarrier bufferMemoryBarrier({}, vk::AccessFlagBits::eShaderRead, VK_QUEUE_FAMILY_IGNORED, VK_QUEUE_FAMILY_IGNORED, *vertexBufferData.buffer, 0,
                                                                        VK_WHOLE_SIZE);
                            commandBuffer->pipelineBarrier(vk::PipelineStageFlagBits::eAllCommands, vk::PipelineStageFlagBits::eAllCommands, {}, nullptr, bufferMemoryBarrier, nullptr);

                            bufferMemoryBarrier.buffer = *indexBufferData.buffer;
                            commandBuffer->pipelineBarrier(vk::PipelineStageFlagBits::eAllCommands, vk::PipelineStageFlagBits::eAllCommands, {}, nullptr, bufferMemoryBarrier, nullptr);
                          });

    std::vector<vk::DescriptorSetLayoutBinding> bindings;
    bindings.push_back(vk::DescriptorSetLayoutBinding(0, vk::DescriptorType::eAccelerationStructureNV, 1, vk::ShaderStageFlagBits::eRaygenNV | vk::ShaderStageFlagBits::eClosestHitNV));
    bindings.push_back(vk::DescriptorSetLayoutBinding(1, vk::DescriptorType::eStorageImage, 1, vk::ShaderStageFlagBits::eRaygenNV));        // raytracing output
    bindings.push_back(vk::DescriptorSetLayoutBinding(2, vk::DescriptorType::eUniformBuffer, 1, vk::ShaderStageFlagBits::eRaygenNV));       // camera information
    bindings.push_back(vk::DescriptorSetLayoutBinding(3, vk::DescriptorType::eStorageBuffer, 1, vk::ShaderStageFlagBits::eClosestHitNV));   // vertex buffer
    bindings.push_back(vk::DescriptorSetLayoutBinding(4, vk::DescriptorType::eStorageBuffer, 1, vk::ShaderStageFlagBits::eClosestHitNV));   // index buffer
    bindings.push_back(vk::DescriptorSetLayoutBinding(5, vk::DescriptorType::eStorageBuffer, 1, vk::ShaderStageFlagBits::eClosestHitNV));   // material buffer
    bindings.push_back(vk::DescriptorSetLayoutBinding(6, vk::DescriptorType::eCombinedImageSampler, vk::su::checked_cast<uint32_t>(textures.size()), vk::ShaderStageFlagBits::eClosestHitNV));   // textures

    std::vector<vk::DescriptorPoolSize> descriptorPoolSizes;
    descriptorPoolSizes.reserve(bindings.size());
    for (const auto& b : bindings)
    {
      descriptorPoolSizes.push_back(vk::DescriptorPoolSize(b.descriptorType, vk::su::checked_cast<uint32_t>(swapChainData.images.size()) * b.descriptorCount));
    }
    vk::DescriptorPoolCreateInfo descriptorPoolCreateInfo(vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet, vk::su::checked_cast<uint32_t>(swapChainData.images.size()),
                                                          vk::su::checked_cast<uint32_t>(descriptorPoolSizes.size()), descriptorPoolSizes.data());
    vk::UniqueDescriptorPool rayTracingDescriptorPool = device->createDescriptorPoolUnique(descriptorPoolCreateInfo);
    vk::UniqueDescriptorSetLayout rayTracingDescriptorSetLayout = device->createDescriptorSetLayoutUnique(vk::DescriptorSetLayoutCreateInfo({}, static_cast<uint32_t>(bindings.size()),
                                                                                                                                            bindings.data()));
    std::vector<vk::DescriptorSetLayout> layouts;
    for (size_t i = 0; i < swapChainData.images.size(); i++)
    {
      layouts.push_back(*rayTracingDescriptorSetLayout);
    }
    vk::DescriptorSetAllocateInfo descriptorSetAllocateInfo(*rayTracingDescriptorPool, vk::su::checked_cast<uint32_t>(layouts.size()), layouts.data());
    std::vector<vk::UniqueDescriptorSet> rayTracingDescriptorSets = device->allocateDescriptorSetsUnique(descriptorSetAllocateInfo);

    // Bind ray tracing specific descriptor sets into pNext of a vk::WriteDescriptorSet
    vk::WriteDescriptorSetAccelerationStructureNV writeDescriptorSetAcceleration(1, &*topLevelAS.acclerationStructure);
    std::vector<vk::WriteDescriptorSet> accelerationDescriptionSets;
    for (size_t i = 0; i < rayTracingDescriptorSets.size(); i++)
    {
      accelerationDescriptionSets.push_back(vk::WriteDescriptorSet(*rayTracingDescriptorSets[i], 0, 0, 1, bindings[0].descriptorType));
      accelerationDescriptionSets.back().pNext = &writeDescriptorSetAcceleration;
    }
    device->updateDescriptorSets(accelerationDescriptionSets, {});

    // Bind all the other buffers and images, starting with dstBinding == 2 (dstBinding == 1 is used by the backBuffer view)
    for (size_t i = 0; i < rayTracingDescriptorSets.size(); i++)
    {
      vk::su::updateDescriptorSets(device, rayTracingDescriptorSets[i],
                                  {
                                    { bindings[2].descriptorType, uniformBufferData.buffer, vk::UniqueBufferView() },
                                    { bindings[3].descriptorType, vertexBufferData.buffer, vk::UniqueBufferView() },
                                    { bindings[4].descriptorType, indexBufferData.buffer, vk::UniqueBufferView() },
                                    { bindings[5].descriptorType, materialBufferData.buffer, vk::UniqueBufferView() }
                                  }, textures, 2);
    }

    // create the ray-tracing shader modules
    glslang::InitializeProcess();
    vk::UniqueShaderModule raygenShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eRaygenNV, raygenShaderText);
    vk::UniqueShaderModule missShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eMissNV, missShaderText);
    vk::UniqueShaderModule shadowMissShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eMissNV, shadowMissShaderText);
    vk::UniqueShaderModule closestHitShaderModule = vk::su::createShaderModule(device, vk::ShaderStageFlagBits::eClosestHitNV, closestHitShaderText);
    glslang::FinalizeProcess();

    // create the ray tracing pipeline
    std::vector<vk::PipelineShaderStageCreateInfo> shaderStages;
    std::vector<vk::RayTracingShaderGroupCreateInfoNV> shaderGroups;

    // We use only one ray generation, that will implement the camera model
    shaderStages.push_back(vk::PipelineShaderStageCreateInfo({}, vk::ShaderStageFlagBits::eRaygenNV, *raygenShaderModule, "main"));
    shaderGroups.push_back(vk::RayTracingShaderGroupCreateInfoNV(vk::RayTracingShaderGroupTypeNV::eGeneral, 0, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV));

    // The first miss shader is used to look-up the environment in case the rays from the camera miss the geometry
    shaderStages.push_back(vk::PipelineShaderStageCreateInfo({}, vk::ShaderStageFlagBits::eMissNV, *missShaderModule, "main"));
    shaderGroups.push_back(vk::RayTracingShaderGroupCreateInfoNV(vk::RayTracingShaderGroupTypeNV::eGeneral, 1, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV));

    // The second miss shader is invoked when a shadow ray misses the geometry. It simply indicates that no occlusion has been found
    shaderStages.push_back(vk::PipelineShaderStageCreateInfo({}, vk::ShaderStageFlagBits::eMissNV, *shadowMissShaderModule, "main"));
    shaderGroups.push_back(vk::RayTracingShaderGroupCreateInfoNV(vk::RayTracingShaderGroupTypeNV::eGeneral, 2, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV));

    // The first hit group defines the shaders invoked when a ray shot from the camera hit the geometry. In this case we only specify the closest hit
    // shader, and rely on the build-in triangle intersection and pass-through any-hit shader. However, explicit intersection and any hit shaders could be added as well.
    shaderStages.push_back(vk::PipelineShaderStageCreateInfo({}, vk::ShaderStageFlagBits::eClosestHitNV, *closestHitShaderModule, "main"));
    shaderGroups.push_back(vk::RayTracingShaderGroupCreateInfoNV(vk::RayTracingShaderGroupTypeNV::eTrianglesHitGroup, VK_SHADER_UNUSED_NV, 3, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV));

    // The second hit group defines the shaders invoked when a shadow ray hits the geometry. For simple shadows we do not need any shader in that group: we will rely on
    // initializing the payload and update it only in the miss shader
    shaderGroups.push_back(vk::RayTracingShaderGroupCreateInfoNV(vk::RayTracingShaderGroupTypeNV::eTrianglesHitGroup, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV, VK_SHADER_UNUSED_NV));

    // Create the layout of the pipeline following the provided descriptor set layout
    vk::UniquePipelineLayout rayTracingPipelineLayout = device->createPipelineLayoutUnique(vk::PipelineLayoutCreateInfo({}, 1, &*rayTracingDescriptorSetLayout));

    // Assemble the shader stages and recursion depth info into the raytracing pipeline
    // The ray tracing process can shoot rays from the camera, and a shadow ray can be shot from the
    // hit points of the camera rays, hence a recursion level of 2. This number should be kept as low
    // as possible for performance reasons. Even recursive ray tracing should be flattened into a loop
    // in the ray generation to avoid deep recursion.
    uint32_t maxRecursionDepth = 2;
    vk::RayTracingPipelineCreateInfoNV rayTracingPipelineCreateInfo({}, static_cast<uint32_t>(shaderStages.size()), shaderStages.data(), static_cast<uint32_t>(shaderGroups.size()),
                                                                    shaderGroups.data(), maxRecursionDepth, *rayTracingPipelineLayout);
    vk::UniquePipeline rayTracingPipeline = device->createRayTracingPipelineNVUnique(nullptr, rayTracingPipelineCreateInfo);

    uint32_t shaderGroupHandleSize = physicalDevice.getProperties2<vk::PhysicalDeviceProperties2, vk::PhysicalDeviceRayTracingPropertiesNV>().get<vk::PhysicalDeviceRayTracingPropertiesNV>().shaderGroupHandleSize;
    assert(!(shaderGroupHandleSize % 16));
    uint32_t shaderBindingTableSize = 5 * shaderGroupHandleSize;    // 1x raygen, 2x miss, 2x hitGroup

    // with 5 shaders, we need a buffer to hold 5 shaderGroupHandles
    std::vector<uint8_t> shaderHandleStorage(shaderBindingTableSize);
    device->getRayTracingShaderGroupHandlesNV<uint8_t>(*rayTracingPipeline, 0, 5, shaderHandleStorage);

    vk::su::BufferData shaderBindingTableBufferData(physicalDevice, device, shaderBindingTableSize, vk::BufferUsageFlagBits::eTransferDst, vk::MemoryPropertyFlagBits::eHostVisible);
    shaderBindingTableBufferData.upload(device, shaderHandleStorage);

    std::array<vk::ClearValue, 2> clearValues;
    clearValues[0].color = vk::ClearColorValue(std::array<float, 4>({0.2f, 0.2f, 0.2f, 0.2f}));
    clearValues[1].depthStencil = vk::ClearDepthStencilValue(1.0f, 0);

    // Main loop
    uint32_t frameIndex = 0;
    UniformBufferObject uniformBufferObject;
    uniformBufferObject.model   = glm::mat4(1);
    uniformBufferObject.modelIT = glm::inverseTranspose(uniformBufferObject.model);

    double accumulatedTime{0.0};
    size_t frameCount{0};
    while (!glfwWindowShouldClose(window))
    {
      double startTime = glfwGetTime();
      glfwPollEvents();

      vk::UniqueCommandBuffer const& commandBuffer = perFrameData[frameIndex].commandBuffer;

      int w, h;
      glfwGetWindowSize(window, &w, &h);
      if ((w != static_cast<int>(windowExtent.width)) || (h != static_cast<int>(windowExtent.height)))
      {
        windowExtent.width = w;
        windowExtent.height = h;
        device->waitIdle();
        swapChainData = vk::su::SwapChainData(physicalDevice, device, surface, windowExtent, vk::ImageUsageFlagBits::eColorAttachment | vk::ImageUsageFlagBits::eStorage, swapChainData.swapChain,
                                              graphicsAndPresentQueueFamilyIndex.first, graphicsAndPresentQueueFamilyIndex.second);
        depthBufferData = vk::su::DepthBufferData(physicalDevice, device, vk::su::pickDepthFormat(physicalDevice), windowExtent);

        vk::su::oneTimeSubmit(commandBuffer, graphicsQueue,
                              [&](vk::UniqueCommandBuffer const& commandBuffer)
                              {
                                vk::su::setImageLayout(commandBuffer, *depthBufferData.image, depthFormat, vk::ImageLayout::eUndefined, vk::ImageLayout::eDepthStencilAttachmentOptimal);
                              });

        framebuffers = vk::su::createFramebuffers(device, renderPass, swapChainData.imageViews, depthBufferData.imageView, windowExtent);
      }

      // update the uniformBufferObject
      assert(0 < windowExtent.height);
      uniformBufferObject.view = appInfo.cameraManipulator.getMatrix();
      uniformBufferObject.proj = glm::perspective(glm::radians(65.0f), windowExtent.width / static_cast<float>(windowExtent.height), 0.1f, 1000.0f);
      uniformBufferObject.proj[1][1] *= -1;  // Inverting Y for Vulkan
      uniformBufferObject.viewInverse = glm::inverse(uniformBufferObject.view);
      uniformBufferObject.projInverse = glm::inverse(uniformBufferObject.proj);
      uniformBufferData.upload(device, uniformBufferObject);

      // frame begin
      vk::ResultValue<uint32_t> rv = device->acquireNextImageKHR(*swapChainData.swapChain, UINT64_MAX, *perFrameData[frameIndex].presentCompleteSemaphore, nullptr);
      assert(rv.result == vk::Result::eSuccess);
      uint32_t backBufferIndex = rv.value;

      while (vk::Result::eTimeout == device->waitForFences(*perFrameData[frameIndex].fence, VK_TRUE, vk::su::FenceTimeout))
        ;
      device->resetFences(*perFrameData[frameIndex].fence);

      commandBuffer->begin(vk::CommandBufferBeginInfo(vk::CommandBufferUsageFlagBits::eOneTimeSubmit));

      if (appInfo.useRasterRender)
      {
        commandBuffer->beginRenderPass(vk::RenderPassBeginInfo(*renderPass, *framebuffers[backBufferIndex], vk::Rect2D(vk::Offset2D(0, 0), windowExtent),
                                                               static_cast<uint32_t>(clearValues.size()), clearValues.data()), vk::SubpassContents::eInline);

        commandBuffer->bindPipeline(vk::PipelineBindPoint::eGraphics, *graphicsPipeline);
        commandBuffer->bindDescriptorSets(vk::PipelineBindPoint::eGraphics, *pipelineLayout, 0, *descriptorSet, nullptr);

        commandBuffer->setViewport(0, vk::Viewport(0.0f, 0.0f, static_cast<float>(windowExtent.width), static_cast<float>(windowExtent.height), 0.0f, 1.0f));
        commandBuffer->setScissor(0, vk::Rect2D(vk::Offset2D(0, 0), windowExtent));

        commandBuffer->bindVertexBuffers(0, *vertexBufferData.buffer, {0});
        commandBuffer->bindIndexBuffer(*indexBufferData.buffer, 0, vk::IndexType::eUint32);
        commandBuffer->drawIndexed(vk::su::checked_cast<uint32_t>(indices.size()), 1, 0, 0, 0);

        commandBuffer->endRenderPass();
      }
      else
      {
        vk::DescriptorImageInfo imageInfo(nullptr, *swapChainData.imageViews[backBufferIndex], vk::ImageLayout::eGeneral);
        device->updateDescriptorSets(vk::WriteDescriptorSet(*rayTracingDescriptorSets[backBufferIndex], 1, 0, 1, bindings[1].descriptorType, &imageInfo), {});

        vk::su::setImageLayout(commandBuffer, swapChainData.images[backBufferIndex], surfaceFormat.format, vk::ImageLayout::eUndefined, vk::ImageLayout::eGeneral);

        commandBuffer->bindPipeline(vk::PipelineBindPoint::eRayTracingNV, *rayTracingPipeline);

        commandBuffer->bindDescriptorSets(vk::PipelineBindPoint::eRayTracingNV, *rayTracingPipelineLayout, 0, *rayTracingDescriptorSets[backBufferIndex], nullptr);

        VkDeviceSize rayGenOffset = 0;                        // starting with raygen
        VkDeviceSize missOffset = shaderGroupHandleSize;      // after raygen
        VkDeviceSize missStride = shaderGroupHandleSize;
        VkDeviceSize hitGroupOffset = shaderGroupHandleSize + 2 * shaderGroupHandleSize;    // after 1x raygen and 2x miss
        VkDeviceSize hitGroupStride = shaderGroupHandleSize;

        commandBuffer->traceRaysNV(*shaderBindingTableBufferData.buffer, rayGenOffset, *shaderBindingTableBufferData.buffer, missOffset, missStride, *shaderBindingTableBufferData.buffer,
                                   hitGroupOffset, hitGroupStride, nullptr, 0, 0, windowExtent.width, windowExtent.height, 1);

        vk::su::setImageLayout(commandBuffer, swapChainData.images[backBufferIndex], surfaceFormat.format, vk::ImageLayout::eGeneral, vk::ImageLayout::ePresentSrcKHR);
      }

      // frame end
      commandBuffer->end();
      const vk::PipelineStageFlags waitDstStageMask = vk::PipelineStageFlagBits::eColorAttachmentOutput;
      graphicsQueue.submit(vk::SubmitInfo(1, &(*perFrameData[frameIndex].presentCompleteSemaphore), &waitDstStageMask, 1, &(*commandBuffer), 1,
                                          &(*perFrameData[frameIndex].renderCompleteSemaphore)), *perFrameData[frameIndex].fence);
      presentQueue.presentKHR(vk::PresentInfoKHR(1, &(*perFrameData[frameIndex].renderCompleteSemaphore), 1, &(*swapChainData.swapChain), &backBufferIndex));
      frameIndex = (frameIndex + 1) % IMGUI_VK_QUEUED_FRAMES;

      double endTime = glfwGetTime();
      accumulatedTime += endTime - startTime;
      ++frameCount;
      if (1.0 < accumulatedTime)
      {
        assert(0 < frameCount);

        std::ostringstream oss;
        oss << AppName << ": " << vertices.size() << " Vertices " << (appInfo.useRasterRender ? "Rastering" : "RayTracing") << " ( " << frameCount / accumulatedTime << " fps)";
        glfwSetWindowTitle(window, oss.str().c_str());

        accumulatedTime = 0.0;
        frameCount = 0;
      }
    }

    // Cleanup
    device->waitIdle();
    swapChainData.swapChain.reset();    // need to reset swapChain before destroying the surface !
    VULKAN_HPP_DEFAULT_DISPATCHER.vkDestroySurfaceKHR(*instance, surface, nullptr);
    glfwDestroyWindow(window);
    glfwTerminate();
  }
  catch (vk::SystemError& err)
  {
    std::cout << "vk::SystemError: " << err.what() << std::endl;
    exit(-1);
  }
  catch (std::runtime_error& err)
  {
    std::cout << "std::runtime_error: " << err.what() << std::endl;
    exit(-1);
  }
  catch (...)
  {
    std::cout << "unknown error\n";
    exit(-1);
  }
  return 0;
}