/*
 * Copyright 2022-2023 Frederico de Oliveira Linhares
 *
 * 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.
 */

#include "graphics_pipeline_3d.hpp"

#include <array>
#include <stdexcept>

#include "../core.hpp"
#include "core.hpp"
#include "image.hpp"
#include "skeletal_mesh_vertex.hpp"
#include "uniform_data_object.hpp"

namespace
{

void
load_world_vert_uniform_buffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  try
  {
    self->ub_world_vert.reserve(cg_core.vk_swapchain->images_count);
    for(auto i{0}; i < cg_core.vk_swapchain->images_count; i++)
      self->ub_world_vert.emplace_back(
	cg_core.vk_device_with_swapchain, sizeof(VK::UDOWorld3D_Vert));
  }
  catch(const std::exception& e)
  {
    throw CommandError{e.what()};
  }
}

void
unload_world_vert_uniform_buffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  self->ub_world_vert.clear();
}

void
load_world_frag_uniform_buffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  try
  {
    self->ub_world_frag.reserve(cg_core.vk_swapchain->images_count);
    for(auto i{0}; i < cg_core.vk_swapchain->images_count; i++)
      self->ub_world_frag.emplace_back(
	cg_core.vk_device_with_swapchain, sizeof(VK::UDOWorld3D_Frag));
  }
  catch(const std::exception& e)
  {
    throw CommandError{e.what()};
  }
}

void
unload_world_frag_uniform_buffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  self->ub_world_frag.clear();
}

void
load_descriptor_pool(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  uint32_t uniform_buffers_count =
    self->ub_world_vert.size() + self->ub_world_vert.size();

  VkDescriptorPoolSize descriptor_pool_size{};
  descriptor_pool_size.type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
  descriptor_pool_size.descriptorCount = uniform_buffers_count;

  VkDescriptorPoolCreateInfo pool_info{};
  pool_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
  pool_info.pNext = nullptr;
  pool_info.flags = 0;
  pool_info.maxSets = uniform_buffers_count;
  pool_info.poolSizeCount = 1;
  pool_info.pPoolSizes = &descriptor_pool_size;

  if(vkCreateDescriptorPool(
       cg_core.vk_device_with_swapchain->device, &pool_info, nullptr,
       &self->descriptor_pool) != VK_SUCCESS)
    throw CommandError{"Failed to create a Vulkan descriptor pool."};
}

void
unload_descriptor_pool(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  vkDestroyDescriptorPool(
    cg_core.vk_device_with_swapchain->device, self->descriptor_pool,
    nullptr);
}

void
load_descriptor_sets_world(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  std::vector<VkDescriptorSetLayout> layouts(
    cg_core.vk_swapchain->images_count,
    cg_core.vk_graphics_pipeline_3d_layout->descriptor_set_world);

  VkDescriptorSetAllocateInfo alloc_info{};
  alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
  alloc_info.descriptorPool = self->descriptor_pool;
  alloc_info.descriptorSetCount = layouts.size();
  alloc_info.pSetLayouts = layouts.data();

  self->descriptor_sets_world.resize(layouts.size());
  if(vkAllocateDescriptorSets(
       cg_core.vk_device_with_swapchain->device, &alloc_info,
       self->descriptor_sets_world.data()) != VK_SUCCESS)
    throw CommandError{"Failed to create Vulkan world descriptor set."};
}

void
load_resources_to_descriptor_sets(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  for(auto i{0}; i < cg_core.vk_swapchain->images_count; i++)
  {
    VkDescriptorBufferInfo world_vert_info{};
    world_vert_info.buffer = self->ub_world_vert[i].buffer;
    world_vert_info.offset = 0;
    world_vert_info.range = sizeof(VK::UDOWorld3D_Vert);

    VkDescriptorBufferInfo world_frag_info{};
    world_frag_info.buffer = self->ub_world_frag[i].buffer;
    world_frag_info.offset = 0;
    world_frag_info.range = sizeof(VK::UDOWorld3D_Frag);

    std::array<VkWriteDescriptorSet, 2> write_descriptors{};
    write_descriptors[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
    write_descriptors[0].dstSet = self->descriptor_sets_world[i];
    write_descriptors[0].dstBinding = 0;
    write_descriptors[0].dstArrayElement = 0;
    write_descriptors[0].descriptorCount = 1;
    write_descriptors[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    write_descriptors[0].pBufferInfo = &world_vert_info;
    write_descriptors[0].pImageInfo = nullptr;
    write_descriptors[0].pTexelBufferView = nullptr;

    write_descriptors[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
    write_descriptors[1].dstSet = self->descriptor_sets_world[i];
    write_descriptors[1].dstBinding = 1;
    write_descriptors[1].dstArrayElement = 0;
    write_descriptors[1].descriptorCount = 1;
    write_descriptors[1].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
    write_descriptors[1].pBufferInfo = &world_frag_info;
    write_descriptors[1].pImageInfo = nullptr;
    write_descriptors[1].pTexelBufferView = nullptr;

    vkUpdateDescriptorSets(
      cg_core.vk_device_with_swapchain->device, write_descriptors.size(),
      write_descriptors.data(), 0, nullptr);
  }
}

void
load_depth_image(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  VkExtent3D extent3d{};
  extent3d.width = cg_core.display_width;
  extent3d.height = cg_core.display_height;
  extent3d.depth = 1;

  try
  {
    VK::Image::create(
      cg_core.vk_device_with_swapchain,
      &self->depth_image,
      &self->depth_image_memory,
      VK_FORMAT_D32_SFLOAT,
      extent3d,
      1,
      VK_IMAGE_TILING_OPTIMAL,
      VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT
      );
  }
  catch(VK::Image::Error error)
  {
    std::string error_message{"Failed to create depth image → "};
    error_message += error.what();
    throw CommandError{error_message};
  }
}

void
unload_depth_image(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  vkDestroyImage(
    cg_core.vk_device_with_swapchain->device, self->depth_image,
    nullptr);
  vkFreeMemory(
    cg_core.vk_device_with_swapchain->device,
    self->depth_image_memory, nullptr);
}

void
load_depth_image_view(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  try
  {
    VK::Image::create_view(
      cg_core.vk_device_with_swapchain, &self->depth_image_view,
      self->depth_image,
      VK_FORMAT_D32_SFLOAT, VK_IMAGE_ASPECT_DEPTH_BIT);
  }
  catch(VK::Image::Error error)
  {
    std::string error_message{"Failed to create depth image view → "};
    error_message += error.what();
    throw CommandError{error_message};
  }
}

void
unload_depth_image_view(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  vkDestroyImageView(
    cg_core.vk_device_with_swapchain->device, self->depth_image_view, nullptr);
}

void
load_framebuffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  self->swapchain_framebuffers.resize(cg_core.vk_swapchain->images_count);
  for (auto i{0}; i < cg_core.vk_swapchain->images_count; i++)
  {
    std::array<VkImageView, 2> attachments = {
      cg_core.vk_swapchain->image_views[i],
      self->depth_image_view
    };

    VkFramebufferCreateInfo framebuffer_info{};
    framebuffer_info.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
    framebuffer_info.renderPass =
      cg_core.vk_graphics_pipeline_3d_layout->render_pass;
    framebuffer_info.attachmentCount = attachments.size();
    framebuffer_info.pAttachments = attachments.data();
    framebuffer_info.width = cg_core.display_width;
    framebuffer_info.height = cg_core.display_height;

    framebuffer_info.layers = 1;

    if(vkCreateFramebuffer(
	 cg_core.vk_device_with_swapchain->device, &framebuffer_info, nullptr,
	 &self->swapchain_framebuffers[i]) != VK_SUCCESS)
      throw CommandError{"Failed to create Vulkan Framebuffer."};
  }
}

void
unload_framebuffer(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  for(auto framebuffer: self->swapchain_framebuffers)
    vkDestroyFramebuffer(
      cg_core.vk_device_with_swapchain->device, framebuffer, nullptr);
}

void
load_pipeline(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  VkPipelineShaderStageCreateInfo vert_shader_stage_info = {};
  vert_shader_stage_info.sType =
      VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
  vert_shader_stage_info.pNext = nullptr;
  vert_shader_stage_info.flags = 0;
  vert_shader_stage_info.stage = VK_SHADER_STAGE_VERTEX_BIT;
  vert_shader_stage_info.module =
    cg_core.vk_device_with_swapchain->vert3d_shader_module;
  vert_shader_stage_info.pName = "main";
  vert_shader_stage_info.pSpecializationInfo = nullptr;

  VkPipelineShaderStageCreateInfo frag_shader_stage_info = {};
  frag_shader_stage_info.sType =
      VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
  frag_shader_stage_info.pNext = nullptr;
  frag_shader_stage_info.flags = 0;
  frag_shader_stage_info.stage = VK_SHADER_STAGE_FRAGMENT_BIT;
  frag_shader_stage_info.module =
    cg_core.vk_device_with_swapchain->frag3d_shader_module;
  frag_shader_stage_info.pName = "main";
  frag_shader_stage_info.pSpecializationInfo = nullptr;

  VkPipelineShaderStageCreateInfo shader_stages[] = {
    vert_shader_stage_info,
    frag_shader_stage_info
  };

  VkVertexInputBindingDescription vertex_input_binding{};
  vertex_input_binding.binding = 0;
  vertex_input_binding.stride = sizeof(VK::SkeletalMeshVertex);
  vertex_input_binding.inputRate = VK_VERTEX_INPUT_RATE_VERTEX;

  std::array<VkVertexInputAttributeDescription, 5> vertex_attribute{};
  // Position.
  vertex_attribute[0].location = 0;
  vertex_attribute[0].binding = 0;
  vertex_attribute[0].format = VK_FORMAT_R32G32B32_SFLOAT;
  vertex_attribute[0].offset = offsetof(VK::SkeletalMeshVertex, position);
  // Normal.
  vertex_attribute[1].location = 1;
  vertex_attribute[1].binding = 0;
  vertex_attribute[1].format = VK_FORMAT_R32G32B32_SFLOAT;
  vertex_attribute[1].offset = offsetof(VK::SkeletalMeshVertex, normal);
  // Texture coordinate.
  vertex_attribute[2].location = 2;
  vertex_attribute[2].binding = 0;
  vertex_attribute[2].format = VK_FORMAT_R32G32_SFLOAT;
  vertex_attribute[2].offset = offsetof(VK::SkeletalMeshVertex, texture_coord);
  // Bones ids.
  vertex_attribute[3].location = 3;
  vertex_attribute[3].binding = 0;
  vertex_attribute[3].format = VK_FORMAT_R32G32B32A32_SINT;
  vertex_attribute[3].offset = offsetof(VK::SkeletalMeshVertex, bone_ids);
  // Bones weights.
  vertex_attribute[4].location = 4;
  vertex_attribute[4].binding = 0;
  vertex_attribute[4].format = VK_FORMAT_R32G32B32A32_SFLOAT;
  vertex_attribute[4].offset = offsetof(VK::SkeletalMeshVertex, bone_weights);

  VkPipelineVertexInputStateCreateInfo vertex_input_info = {};
  vertex_input_info.sType =
      VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
  vertex_input_info.pNext = nullptr;
  vertex_input_info.flags = 0;
  vertex_input_info.vertexBindingDescriptionCount = 1;
  vertex_input_info.pVertexBindingDescriptions = &vertex_input_binding;
  vertex_input_info.vertexAttributeDescriptionCount =
      static_cast<uint32_t>(vertex_attribute.size());
  vertex_input_info.pVertexAttributeDescriptions = vertex_attribute.data();

  VkPipelineInputAssemblyStateCreateInfo input_assembly = {};
  input_assembly.sType =
      VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
  input_assembly.pNext = nullptr;
  input_assembly.flags = 0;
  input_assembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
  input_assembly.primitiveRestartEnable = VK_FALSE;

  VkViewport viewport = {};
  viewport.x = 0;
  viewport.y = 0;
  viewport.width = cg_core.display_width;
  viewport.height = cg_core.display_height;
  viewport.minDepth = 0.0f;
  viewport.maxDepth = 1.0f;

  VkRect2D scissor = {};
  scissor.offset = {0, 0};
  scissor.extent = {cg_core.display_width, cg_core.display_height};

  VkPipelineViewportStateCreateInfo viewport_state = {};
  viewport_state.sType =
      VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
  viewport_state.pNext = nullptr;
  viewport_state.flags = 0;
  viewport_state.viewportCount = 1;
  viewport_state.pViewports = &viewport;
  viewport_state.scissorCount = 1;
  viewport_state.pScissors = &scissor;

  VkPipelineRasterizationStateCreateInfo rasterizer = {};
  rasterizer.sType =
      VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
  rasterizer.pNext = nullptr;
  rasterizer.flags = 0;
  rasterizer.depthClampEnable = VK_FALSE;
  rasterizer.rasterizerDiscardEnable = VK_FALSE;
  rasterizer.polygonMode = VK_POLYGON_MODE_FILL;
  rasterizer.cullMode = VK_CULL_MODE_NONE;
  rasterizer.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE;
  rasterizer.depthBiasEnable = VK_FALSE;
  rasterizer.depthBiasConstantFactor = 0.0f;
  rasterizer.depthBiasClamp = 0.0f;
  rasterizer.depthBiasSlopeFactor = 0.0f;
  rasterizer.lineWidth = 1.0f;

  VkPipelineMultisampleStateCreateInfo multisampling = {};
  multisampling.sType =
      VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
  multisampling.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
  multisampling.sampleShadingEnable = VK_FALSE;
  multisampling.minSampleShading = 1.0f;
  multisampling.pSampleMask = nullptr;
  multisampling.alphaToCoverageEnable = VK_FALSE;
  multisampling.alphaToOneEnable = VK_FALSE;

  VkPipelineDepthStencilStateCreateInfo depth_stencil = {};
  depth_stencil.sType =
    VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO;
  depth_stencil.depthTestEnable = VK_TRUE;
  depth_stencil.depthWriteEnable = VK_TRUE;
  depth_stencil.depthCompareOp = VK_COMPARE_OP_LESS;
  depth_stencil.depthBoundsTestEnable = VK_FALSE;
  depth_stencil.minDepthBounds = 0.0f;
  depth_stencil.maxDepthBounds = 1.0f;
  depth_stencil.stencilTestEnable = VK_FALSE;
  depth_stencil.front = {};
  depth_stencil.back = {};

  VkPipelineColorBlendAttachmentState color_blend_attachment = {};
  color_blend_attachment.blendEnable = VK_FALSE;
  color_blend_attachment.srcColorBlendFactor = VK_BLEND_FACTOR_ONE;
  color_blend_attachment.dstColorBlendFactor = VK_BLEND_FACTOR_ZERO;
  color_blend_attachment.colorBlendOp = VK_BLEND_OP_ADD;
  color_blend_attachment.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE;
  color_blend_attachment.dstAlphaBlendFactor = VK_BLEND_FACTOR_ZERO;
  color_blend_attachment.alphaBlendOp = VK_BLEND_OP_ADD;
  color_blend_attachment.colorWriteMask =
      VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT |
      VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;

  VkPipelineColorBlendStateCreateInfo color_blending = {};
  color_blending.sType =
      VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
  color_blending.pNext = nullptr;
  color_blending.flags = 0;
  color_blending.logicOpEnable = VK_FALSE;
  color_blending.logicOp = VK_LOGIC_OP_COPY;
  color_blending.attachmentCount = 1;
  color_blending.pAttachments = &color_blend_attachment;
  color_blending.blendConstants[0] = 0.0f;
  color_blending.blendConstants[1] = 0.0f;
  color_blending.blendConstants[2] = 0.0f;
  color_blending.blendConstants[3] = 0.0f;

  VkDynamicState dynamic_states[] = {
    VK_DYNAMIC_STATE_VIEWPORT,
    VK_DYNAMIC_STATE_LINE_WIDTH
  };

  VkPipelineDynamicStateCreateInfo dynamic_state_info = {};
  dynamic_state_info.sType =
      VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO;
  dynamic_state_info.dynamicStateCount = 2;
  dynamic_state_info.pDynamicStates = dynamic_states;

  VkGraphicsPipelineCreateInfo pipeline_info{};
  pipeline_info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
  pipeline_info.pNext = nullptr;
  pipeline_info.flags = 0;
  pipeline_info.stageCount = 2;
  pipeline_info.pStages = shader_stages;
  pipeline_info.pVertexInputState = &vertex_input_info;
  pipeline_info.pInputAssemblyState = &input_assembly;
  pipeline_info.pTessellationState = nullptr;
  pipeline_info.pViewportState = &viewport_state;
  pipeline_info.pRasterizationState = &rasterizer;
  pipeline_info.pMultisampleState = &multisampling;
  pipeline_info.pDepthStencilState = &depth_stencil;
  pipeline_info.pColorBlendState = &color_blending;
  pipeline_info.pDynamicState = &dynamic_state_info;
  pipeline_info.layout = cg_core.vk_graphics_pipeline_3d_layout->pipeline;
  pipeline_info.renderPass =
    cg_core.vk_graphics_pipeline_3d_layout->render_pass;
  pipeline_info.subpass = 0;
  pipeline_info.basePipelineHandle = VK_NULL_HANDLE;
  pipeline_info.basePipelineIndex = -1;

  if(vkCreateGraphicsPipelines(
       cg_core.vk_device_with_swapchain->device, VK_NULL_HANDLE, 1,
       &pipeline_info, nullptr, &self->graphic_pipeline)
     != VK_SUCCESS)
    throw CommandError{"Failed to create graphics pipeline."};
}

void
unload_pipeline(void *obj)
{
  auto self = static_cast<VK::GraphicsPipeline3DSkeletal*>(obj);

  vkDestroyPipeline(
    cg_core.vk_device_with_swapchain->device, self->graphic_pipeline, nullptr);
}

const CommandChain loader{
  {&load_world_vert_uniform_buffer, &unload_world_vert_uniform_buffer},
  {&load_world_frag_uniform_buffer, &unload_world_frag_uniform_buffer},
  {&load_descriptor_pool, &unload_descriptor_pool},
  // By destroying the pool the sets are also destroyed.
  {&load_descriptor_sets_world, nullptr},
  {&load_resources_to_descriptor_sets, nullptr},
  {&load_depth_image, &unload_depth_image},
  {&load_depth_image_view, &unload_depth_image_view},
  {&load_framebuffer, &unload_framebuffer},
  {&load_pipeline, &unload_pipeline}
};

}

namespace VK
{

GraphicsPipeline3DSkeletal::GraphicsPipeline3DSkeletal()
{
  loader.execute(this);
}

GraphicsPipeline3DSkeletal::~GraphicsPipeline3DSkeletal()
{
  loader.revert(this);
}

void
GraphicsPipeline3DSkeletal::draw(
  std::shared_ptr<View3D> view, const VkCommandBuffer draw_command_buffer,
  const size_t current_frame, const uint32_t image_index)
{
  { // Set viewport
    VkViewport vk_viewport{};
    vk_viewport.x = view->region.x;
    vk_viewport.y = view->region.y;
    vk_viewport.width = view->region.z;
    vk_viewport.height = view->region.w;
    vk_viewport.minDepth = 0.0f;
    vk_viewport.maxDepth = 1.0f;
    vkCmdSetViewport(draw_command_buffer, 0, 1, &vk_viewport);

    VkRect2D vk_scissor{};
    vk_scissor.offset.x = static_cast<int32_t>(view->region.x);
    vk_scissor.offset.y = static_cast<int32_t>(view->region.y);
    vk_scissor.extent.width = static_cast<uint32_t>(view->region.z);
    vk_scissor.extent.height = static_cast<uint32_t>(view->region.w);
    vkCmdSetScissor(draw_command_buffer, 0, 1, &vk_scissor);
  }

  // Draw models
  for(auto& [skeletal_mesh, instances]:
	cg_core.vk_renderer->skeletal_models_to_draw[current_frame])
  {
      VkBuffer vertex_buffers[]{skeletal_mesh->vertex_buffer->buffer};
      VkDeviceSize offsets[]{0};

      vkCmdBindPipeline(
	draw_command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS,
	this->graphic_pipeline);
      vkCmdBindVertexBuffers(
	draw_command_buffer, 0, 1, vertex_buffers, offsets);
      vkCmdBindIndexBuffer(
	draw_command_buffer, skeletal_mesh->index_buffer->buffer, 0,
	VK_INDEX_TYPE_UINT32);

      for(auto &instance: instances)
      { // Object matrix.
        glm::mat4 base_matrix{1.0f};
        base_matrix = glm::translate(base_matrix, *instance->position);
        base_matrix = glm::rotate(
          base_matrix, instance->rotation->x, glm::vec3{1.0, 0.0, 0.0});
        base_matrix = glm::rotate(
          base_matrix, instance->rotation->y, glm::vec3{0.0, 1.0, 0.0});
        base_matrix = glm::rotate(
          base_matrix, instance->rotation->z, glm::vec3{0.0, 0.0, 1.0});

	std::array<VkDescriptorSet, 3> vk_descriptor_sets{
	  this->descriptor_sets_world[image_index],
	  view->descriptor_sets_3d[image_index],
	  instance->descriptor_sets[image_index]};

	vkCmdBindDescriptorSets(
	  draw_command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS,
	  cg_core.vk_graphics_pipeline_3d_layout->pipeline, 0,
	  vk_descriptor_sets.size(), vk_descriptor_sets.data(), 0, nullptr);

        vkCmdDrawIndexed(
          draw_command_buffer, skeletal_mesh->index_count, 1, 0, 0, 0);

	VK::UDOSkeletalModel udo_skeletal_model{};
	instance->tick(cg_core.delta_time);
	udo_skeletal_model.base_matrix = base_matrix;
	std::copy(instance->bone_transforms.begin(),
		  instance->bone_transforms.end(),
		  udo_skeletal_model.bone_matrices);
	instance->uniform_buffers[image_index].copy_data(&udo_skeletal_model);
      }
  }

  { // Update view uniform buffers
    VK::UDOView3D ubo_view_3d{};

    // View matrix.
    ubo_view_3d.view = glm::mat4{1.0f};
    ubo_view_3d.view = glm::translate(
      ubo_view_3d.view, *view->camera_position);
    ubo_view_3d.view = glm::rotate(
      ubo_view_3d.view, view->camera_rotation->y, glm::vec3{0.0, 1.0, 0.0});
    ubo_view_3d.view = glm::rotate(
      ubo_view_3d.view, view->camera_rotation->x, glm::vec3{1.0, 0.0, 0.0});
    ubo_view_3d.view = glm::rotate(
      ubo_view_3d.view, view->camera_rotation->z, glm::vec3{0.0, 0.0, 1.0});
    ubo_view_3d.view = glm::inverse(ubo_view_3d.view);

    // Projection matrix.
    ubo_view_3d.proj = glm::perspective(
      glm::radians(45.0f),
      view->region.z / view->region.w,
      0.1f, 100.0f);

    view->ub_3d[image_index].copy_data(&ubo_view_3d);
  }

  // TODO: Do not update this for each view. All views use the same data.
  { // Update world uniform buffer
    UDOWorld3D_Vert ubo_world_3d_vert{};
    ubo_world_3d_vert.ambient_light_color = glm::vec4{0.25, 0.25, 0.25, 1.0};
    this->ub_world_vert[image_index].copy_data(&ubo_world_3d_vert);

    UDOWorld3D_Frag ubo_world_3d_frag{};
    ubo_world_3d_frag.directional_light_direction =
      glm::vec3{-0.57735, 0.57735, -0.57735};
    ubo_world_3d_frag.directional_light_color = glm::vec4{0.8, 0.8, 0.8, 1.0};
    this->ub_world_frag[image_index].copy_data(&ubo_world_3d_frag);
  }
}

}