Use indirect draw call.

src/VulkanTutorial.cpp

@@ -241,6 +241,25 @@ void VulkanTutorial::draw_frame() {
     std::memcpy(uniform_buffer, &uniforms, sizeof(Uniforms));
     m_uniform_buffer_memory.unmap(m_context);
 
+    std::vector<VkDrawIndexedIndirectCommand> draw_commands {
+        {
+            .indexCount = uint32_t(indices.size()),
+            .instanceCount = 1,
+        },
+    };
+    Byte* draw_buffer = image_states.m_draw_buffer.memory().map(
+        m_context,
+        0,
+        DrawBufferOffset + 1 * sizeof(VkDrawIndexedIndirectCommand)
+    );
+    *reinterpret_cast<uint32_t*>(draw_buffer) = uint32_t(draw_commands.size());
+    std::memcpy(
+        draw_buffer + DrawBufferOffset,
+        draw_commands.data(),
+        draw_commands.size() * sizeof(VkDrawIndexedIndirectCommand)
+    );
+    image_states.m_draw_buffer.memory().unmap(m_context);
+
     VkSemaphore wait_semaphores[] = {
         m_swapchain.ready_to_render(),
     };
@@ -559,6 +578,8 @@ void VulkanTutorial::initialize_image_states(size_t image_index) {
     create_uniform_buffer(image_states);
     create_descriptor_set(image_states);
 
+    create_draw_buffer(image_states);
+
     create_command_buffer(image_states);
 
     image_states.m_render_done = vk::Semaphore(m_context);
@@ -636,6 +657,16 @@ void VulkanTutorial::create_descriptor_set(ImageStates& image_states) {
     );
 }
 
+void VulkanTutorial::create_draw_buffer(ImageStates& image_states) {
+    image_states.m_draw_buffer = vk::Buffer(
+        m_context,
+        DrawBufferOffset + MaxDrawTileCount * sizeof(VkDrawIndexedIndirectCommand),
+        VK_BUFFER_USAGE_INDIRECT_BUFFER_BIT,
+        VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT
+        | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT
+    );
+}
+
 void VulkanTutorial::create_command_buffer(ImageStates& image_states) {
     image_states.m_command_buffer = vk::CommandBuffer(m_context, m_command_pool);
 
@@ -716,13 +747,14 @@ void VulkanTutorial::create_command_buffer(ImageStates& image_states) {
         0, nullptr
     );
 
-    vkCmdDrawIndexed(
+    m_context.cmdDrawIndexedIndirectCount(
         image_states.m_command_buffer,
-        uint32_t(indices.size()),
+        image_states.m_draw_buffer,
-        1,
+        DrawBufferOffset,
-        0,
+        image_states.m_draw_buffer,
         0,
-        0
+        MaxDrawTileCount,
+        sizeof(VkDrawIndexedIndirectCommand)
     );
 
     vkCmdEndRenderPass(image_states.m_command_buffer);

src/VulkanTutorial.h

@@ -84,8 +84,14 @@ private:
     void create_uniform_buffer(ImageStates& image_states);
     void create_descriptor_set(ImageStates& image_states);
 
+    void create_draw_buffer(ImageStates& image_states);
+
     void create_command_buffer(ImageStates& image_states);
 
+private:
+    static constexpr uint32_t DrawBufferOffset = 4;
+    static constexpr uint32_t MaxDrawTileCount = 256;
+
 private:
     vk::Context m_context;
 
@@ -117,6 +123,8 @@ private:
         VkDeviceSize m_uniform_buffer_offset;
         vk::DescriptorSet m_descriptor_set;
 
+        vk::Buffer m_draw_buffer;
+
         vk::CommandBuffer m_command_buffer;
         vk::Semaphore m_render_done;
     };

src/vk/Context.cpp

@@ -562,7 +562,7 @@ void Context::create_instance(const ContextSettings& settings) {
     if(vkCreateInstance(&instance_info, nullptr, &m_instance) != VK_SUCCESS)
         throw std::runtime_error("failed to create vulkan instance");
 
-    initialize_extension_functions();
+    initialize_instance_extension_functions();
 
     if(settings.debug()) {
         createDebugUtilsMessenger(
@@ -733,7 +733,9 @@ void Context::create_device(const ContextSettings& settings) {
         .geometryShader = true,
     };
 
-    std::vector<const char*> extensions;
+    std::vector<const char*> extensions {
+        VK_KHR_DRAW_INDIRECT_COUNT_EXTENSION_NAME,
+    };
     if(m_window) {
         extensions.push_back(VK_KHR_SWAPCHAIN_EXTENSION_NAME);
     };
@@ -756,6 +758,8 @@ void Context::create_device(const ContextSettings& settings) {
     ) != VK_SUCCESS)
         throw std::runtime_error("failed to create logical device");
 
+    initialize_device_extension_functions();
+
     m_queues.resize(m_queue_families.size());
     for(size_t index = 0; index < m_queue_families.size(); ++index) {
         vkGetDeviceQueue(
@@ -777,10 +781,10 @@ void Context::create_internal_objects() {
     m_transfer_fence = Fence(*this);
 }
 
-void Context::initialize_extension_functions() {
+void Context::initialize_instance_extension_functions() {
     uint32_t errors_count = 0;
 
-    #define GET_PROC_ADDR(ptr_name, func_name) \
+    #define GET_INSTANCE_PROC_ADDR(ptr_name, func_name) \
         ptr_name = (PFN_vk ## func_name)vkGetInstanceProcAddr( \
             m_instance, "vk" #func_name); \
         if(ptr_name == nullptr) \
@@ -789,9 +793,27 @@ void Context::initialize_extension_functions() {
             errors_count += 1; \
         }
 
-    GET_PROC_ADDR(createDebugUtilsMessenger, CreateDebugUtilsMessengerEXT)
+    GET_INSTANCE_PROC_ADDR(createDebugUtilsMessenger, CreateDebugUtilsMessengerEXT)
-    GET_PROC_ADDR(destroyDebugUtilsMessenger, DestroyDebugUtilsMessengerEXT)
+    GET_INSTANCE_PROC_ADDR(destroyDebugUtilsMessenger, DestroyDebugUtilsMessengerEXT)
-    GET_PROC_ADDR(setDebugUtilsObjectName, SetDebugUtilsObjectNameEXT)
+    GET_INSTANCE_PROC_ADDR(setDebugUtilsObjectName, SetDebugUtilsObjectNameEXT)
+
+    if(errors_count != 0)
+        throw std::runtime_error("failed to load extensions");
+}
+
+void Context::initialize_device_extension_functions() {
+    uint32_t errors_count = 0;
+
+    #define GET_DEVICE_PROC_ADDR(ptr_name, func_name) \
+        ptr_name = (PFN_vk ## func_name)vkGetDeviceProcAddr( \
+            m_device, "vk" #func_name); \
+        if(ptr_name == nullptr) \
+        { \
+            logger.error() << "failed to load extension function 'vk" #func_name "'"; \
+            errors_count += 1; \
+        }
+
+    GET_DEVICE_PROC_ADDR(cmdDrawIndexedIndirectCount, CmdDrawIndexedIndirectCountKHR)
 
     if(errors_count != 0)
         throw std::runtime_error("failed to load extensions");

src/vk/Context.h

@@ -154,6 +154,8 @@ public:
     PFN_vkDestroyDebugUtilsMessengerEXT destroyDebugUtilsMessenger = nullptr;
     PFN_vkSetDebugUtilsObjectNameEXT setDebugUtilsObjectName = nullptr;
 
+    PFN_vkCmdDrawIndexedIndirectCountKHR cmdDrawIndexedIndirectCount = nullptr;
+
 private:
     void create_instance(const ContextSettings& settings);
     void create_surface(const ContextSettings& settings);
@@ -165,7 +167,8 @@ private:
     void create_device(const ContextSettings& settings);
     void create_internal_objects();
 
-    void initialize_extension_functions();
+    void initialize_instance_extension_functions();
+    void initialize_device_extension_functions();
 
     static VKAPI_ATTR VkBool32 VKAPI_CALL log_debug_message(
         VkDebugUtilsMessageSeverityFlagBitsEXT severity,

src/vk/Memory.cpp

@@ -80,11 +80,11 @@ void MemoryBlock::free() noexcept {
 }
 
 
-void* MemoryBlock::map(Context& context) {
+Byte* MemoryBlock::map(Context& context) {
     return map(context, 0, m_size);
 }
 
-void* MemoryBlock::map(Context& context, VkDeviceSize offset, VkDeviceSize size) {
+Byte* MemoryBlock::map(Context& context, VkDeviceSize offset, VkDeviceSize size) {
     assert(!is_null());
     assert(context);
     assert(offset + size <= m_size);
@@ -100,7 +100,7 @@ void* MemoryBlock::map(Context& context, VkDeviceSize offset, VkDeviceSize size)
     ) != VK_SUCCESS)
         throw std::runtime_error("failed to map memory");
 
-    return ptr;
+    return reinterpret_cast<Byte*>(ptr);
 }
 
 void MemoryBlock::unmap(Context& context) noexcept {

src/vk/Memory.h

@@ -1,6 +1,8 @@
 // Copyright 2022 Simon Boyé
 #pragma once
 
+#include <core/types.h>
+
 #include <vk/forward.h>
 
 #include <vulkan/vulkan.h>
@@ -61,8 +63,8 @@ public:
 
     void free() noexcept;
 
-    void* map(Context& context);
+    Byte* map(Context& context);
-    void* map(Context& context, VkDeviceSize offset, VkDeviceSize size);
+    Byte* map(Context& context, VkDeviceSize offset, VkDeviceSize size);
     void unmap(Context& context) noexcept;
 
     void flush(Context& context);