Multiple frames in flight

src/main.c

@@ -59,21 +59,26 @@ typedef struct VulkanContextStruct {
   VkExtent2D swapchain_extent;
 
   uint32_t swapchain_image_count;
+  // Per image objects
   VkImage* swapchain_images;
   VkImageView* swapchain_image_views;
   VkFramebuffer* swapchain_framebuffers;
 
+  uint32_t max_frames_in_flight;
+  // Per frame objects
+  VkCommandBuffer* swapchain_command_buffers;
+  VkSemaphore* image_available_semaphores;
+  VkSemaphore* render_finished_semaphores;
+  VkFence* in_flight_fences;
+
   VkRenderPass render_pass;
 
   VkCommandPool graphics_command_pool;
 
-  VkCommandBuffer triangle_command_buffer;
   VkPipelineLayout triangle_pipeline_layout;
   VkPipeline triangle_pipeline;
 
-  VkSemaphore image_available_semaphore;
-  VkSemaphore render_finished_semaphore;
-  VkFence in_flight_fence;
+  uint32_t current_frame;
 } VulkanContext;
 
 const char * validation_layers[] = {
@@ -885,50 +890,67 @@ VkResult record_command_buffer_triangle(VkCommandBuffer command_buffer, uint32_t
   return vkEndCommandBuffer(command_buffer);
 }
 
-VkCommandBuffer create_command_buffer(VkDevice device, VkCommandPool command_pool)  {
+VkCommandBuffer* create_command_buffers(VkDevice device, VkCommandPool command_pool, uint32_t image_count)  {
   VkCommandBufferAllocateInfo alloc_info = {};
   alloc_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
   alloc_info.commandPool = command_pool;
   alloc_info.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
-  alloc_info.commandBufferCount = 1;
+  alloc_info.commandBufferCount = image_count;
 
-  VkCommandBuffer command_buffer;
-  VkResult result = vkAllocateCommandBuffers(device, &alloc_info, &command_buffer);
+  VkCommandBuffer* command_buffers = malloc(sizeof(VkCommandBuffer)*image_count);
+  if(command_buffers == 0) {
+    return 0;
+  }
+
+  VkResult result = vkAllocateCommandBuffers(device, &alloc_info, command_buffers);
   if(result != VK_SUCCESS) {
     return VK_NULL_HANDLE;
   }
 
-  return command_buffer;
+  return command_buffers;
 }
 
-VkSemaphore create_semaphore(VkDevice device, VkSemaphoreCreateFlags flags) {
+VkSemaphore* create_semaphores(VkDevice device, VkSemaphoreCreateFlags flags, uint32_t count) {
+  VkSemaphore* semaphores = malloc(sizeof(VkSemaphore)*count);
+  if(semaphores == 0) {
+    return 0;
+  }
+
   VkSemaphoreCreateInfo semaphore_info = {};
   semaphore_info.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;
   semaphore_info.flags = flags;
 
-  VkSemaphore semaphore;
-  VkResult result = vkCreateSemaphore(device, &semaphore_info, 0, &semaphore);
+  for(uint32_t i = 0; i < count; i++) {
+    VkResult result = vkCreateSemaphore(device, &semaphore_info, 0, &semaphores[i]);
     if(result != VK_SUCCESS) {
-    return VK_NULL_HANDLE;
+      free(semaphores);
+      return 0;
     }
-
-  return semaphore;
+  }
+  return semaphores;
 }
 
-VkFence create_fence(VkDevice device, VkFenceCreateFlags flags) {
+VkFence* create_fences(VkDevice device, VkFenceCreateFlags flags, uint32_t count) {
+  VkFence* fences = malloc(sizeof(VkFence)*count);
+  if(fences == 0) {
+    return 0;
+  }
+
   VkFenceCreateInfo fence_info = {};
   fence_info.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
   fence_info.flags = flags;
 
-  VkFence fence;
-  VkResult result = vkCreateFence(device, &fence_info, 0, &fence);
+  for(uint32_t i = 0; i < count; i++) {
+    VkResult result = vkCreateFence(device, &fence_info, 0, &fences[i]);
     if(result != VK_SUCCESS) {
-    return VK_NULL_HANDLE;
+      free(fences);
+      return 0;
+    }
   }
-  return fence;
+  return fences;
 }
 
-VulkanContext* init_vulkan(GLFWwindow* window) {
+VulkanContext* init_vulkan(GLFWwindow* window, uint32_t max_frames_in_flight) {
   VulkanContext* context = (VulkanContext*)malloc(sizeof(VulkanContext));
 
   VkInstance instance = create_instance();
@@ -1034,36 +1056,46 @@ VulkanContext* init_vulkan(GLFWwindow* window) {
     context->swapchain_framebuffers = framebuffers;
   }
 
-  VkSemaphore ia_semaphore = create_semaphore(context->device, 0);
-  if(ia_semaphore == VK_NULL_HANDLE) {
-    fprintf(stderr, "failed to create vulkan image available semaphore\n");
+  VkCommandPool command_pool = create_command_pool(context->device, context->queue_indices.graphics_family);
+  if(command_pool == VK_NULL_HANDLE) {
+    fprintf(stderr, "failed to create vulkan graphics command pool");
+    return 0;
+  } else {
+    context->graphics_command_pool = command_pool;
+  }
+
+  context->max_frames_in_flight = max_frames_in_flight;
+
+  VkCommandBuffer* swapchain_command_buffers = create_command_buffers(context->device, context->graphics_command_pool, max_frames_in_flight);
+  if(swapchain_command_buffers == VK_NULL_HANDLE) {
+    fprintf(stderr, "failed to create vulkan swapchain command buffer\n");
     return 0;
   } else {
-    context->image_available_semaphore = ia_semaphore;
+    context->swapchain_command_buffers = swapchain_command_buffers;
   }
 
-  VkSemaphore rf_semaphore = create_semaphore(context->device, 0);
-  if(rf_semaphore == VK_NULL_HANDLE) {
-    fprintf(stderr, "failed to create vulkan render finished semaphore\n");
+  VkSemaphore* ia_semaphores = create_semaphores(context->device, 0, max_frames_in_flight);
+  if(ia_semaphores == 0) {
+    fprintf(stderr, "failed to create vulkan image available semaphores\n");
     return 0;
   } else {
-    context->render_finished_semaphore = rf_semaphore;
+    context->image_available_semaphores = ia_semaphores;
   }
 
-  VkFence if_fence = create_fence(context->device, VK_FENCE_CREATE_SIGNALED_BIT);
-  if(if_fence == VK_NULL_HANDLE) {
-    fprintf(stderr, "failed to create vulkan in flight fence\n");
+  VkSemaphore* rf_semaphores = create_semaphores(context->device, 0, max_frames_in_flight);
+  if(rf_semaphores == 0) {
+    fprintf(stderr, "failed to create vulkan render finished semaphores\n");
     return 0;
   } else {
-    context->in_flight_fence = if_fence;
+    context->render_finished_semaphores = rf_semaphores;
   }
 
-  VkCommandPool command_pool = create_command_pool(context->device, context->queue_indices.graphics_family);
-  if(command_pool == VK_NULL_HANDLE) {
-    fprintf(stderr, "failed to create vulkan graphics command pool");
+  VkFence* if_fences = create_fences(context->device, VK_FENCE_CREATE_SIGNALED_BIT, max_frames_in_flight);
+  if(if_fences == 0) {
+    fprintf(stderr, "failed to create vulkan in flight fence\n");
     return 0;
   } else {
-    context->graphics_command_pool = command_pool;
+    context->in_flight_fences = if_fences;
   }
 
   VkPipelineLayout triangle_pipeline_layout = create_pipeline_layout(device, 0, 0, 0, 0);
@@ -1082,41 +1114,33 @@ VulkanContext* init_vulkan(GLFWwindow* window) {
     context->triangle_pipeline = triangle_pipeline;
   }
 
-  VkCommandBuffer triangle_command_buffer = create_command_buffer(context->device, context->graphics_command_pool);
-  if(triangle_command_buffer == VK_NULL_HANDLE) {
-    fprintf(stderr, "failed to create vulkan triangle command buffer\n");
-    return 0;
-  } else {
-    context->triangle_command_buffer = triangle_command_buffer;
-  }
-
   return context;
 }
 
 VkResult draw_frame(VulkanContext* context) {
   VkResult result;
-  result = vkWaitForFences(context->device, 1, &context->in_flight_fence, VK_TRUE, UINT64_MAX);
+  result = vkWaitForFences(context->device, 1, &context->in_flight_fences[context->current_frame], VK_TRUE, UINT64_MAX);
   if(result != VK_SUCCESS) {
     return result;
   }
 
-  result = vkResetFences(context->device, 1, &context->in_flight_fence);
+  result = vkResetFences(context->device, 1, &context->in_flight_fences[context->current_frame]);
   if(result != VK_SUCCESS) {
     return result;
   }
 
   uint32_t image_index;
-  result = vkAcquireNextImageKHR(context->device, context->swapchain, UINT64_MAX, context->image_available_semaphore, VK_NULL_HANDLE, &image_index);
+  result = vkAcquireNextImageKHR(context->device, context->swapchain, UINT64_MAX, context->image_available_semaphores[context->current_frame], VK_NULL_HANDLE, &image_index);
   if(result != VK_SUCCESS) {
     return result;
   }
 
-  result = vkResetCommandBuffer(context->triangle_command_buffer, 0);
+  result = vkResetCommandBuffer(context->swapchain_command_buffers[context->current_frame], 0);
   if(result != VK_SUCCESS) {
     return result;
   }
 
-  result = record_command_buffer_triangle(context->triangle_command_buffer, image_index, context->render_pass, context->swapchain_framebuffers, context->swapchain_extent, context->triangle_pipeline);
+  result = record_command_buffer_triangle(context->swapchain_command_buffers[context->current_frame], image_index, context->render_pass, context->swapchain_framebuffers, context->swapchain_extent, context->triangle_pipeline);
   if(result != VK_SUCCESS) {
     return result;
   }
@@ -1125,14 +1149,14 @@ VkResult draw_frame(VulkanContext* context) {
   VkPipelineStageFlags wait_stages[] = {VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT};
   submit_info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
   submit_info.waitSemaphoreCount = 1;
-  submit_info.pWaitSemaphores = &context->image_available_semaphore;
+  submit_info.pWaitSemaphores = &context->image_available_semaphores[context->current_frame];
   submit_info.pWaitDstStageMask = wait_stages;
   submit_info.commandBufferCount = 1;
-  submit_info.pCommandBuffers = &context->triangle_command_buffer;
+  submit_info.pCommandBuffers = &context->swapchain_command_buffers[context->current_frame];
   submit_info.signalSemaphoreCount = 1;
-  submit_info.pSignalSemaphores = &context->render_finished_semaphore;
+  submit_info.pSignalSemaphores = &context->render_finished_semaphores[context->current_frame];
 
-  result = vkQueueSubmit(context->queues.graphics, 1, &submit_info, context->in_flight_fence);
+  result = vkQueueSubmit(context->queues.graphics, 1, &submit_info, context->in_flight_fences[context->current_frame]);
   if(result != VK_SUCCESS) {
     return result;
   }
@@ -1140,7 +1164,7 @@ VkResult draw_frame(VulkanContext* context) {
   VkPresentInfoKHR present_info = {};
   present_info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
   present_info.waitSemaphoreCount = 1;
-  present_info.pWaitSemaphores = &context->render_finished_semaphore;
+  present_info.pWaitSemaphores = &context->render_finished_semaphores[context->current_frame];
   present_info.swapchainCount = 1;
   present_info.pSwapchains = &context->swapchain;
   present_info.pImageIndices = &image_index;
@@ -1150,10 +1174,17 @@ VkResult draw_frame(VulkanContext* context) {
 }
 
 void main_loop(GLFWwindow* window, VulkanContext* context) {
+  context->current_frame = 0;
   while(!glfwWindowShouldClose(window)) {
     glfwPollEvents();
     draw_frame(context);
+    context->current_frame += 1;
+    if(context->current_frame >= context->max_frames_in_flight) {
+      context->current_frame = 0;
     }
+  }
+
+  vkDeviceWaitIdle(context->device);
 }
 
 void cleanup(GLFWwindow* window, VulkanContext* context) {
@@ -1194,7 +1225,7 @@ int main() {
     return 1;
   }
 
-  VulkanContext* context = init_vulkan(window);
+  VulkanContext* context = init_vulkan(window, 2);
   if (context == 0) {
     fprintf(stderr, "failed to initialize vulkan context\n");
     return 2;