Backends: Vulkan: Make descriptor pool optional (#8172, #4867)
Comments/amends by ocornut
diff --git a/backends/imgui_impl_vulkan.cpp b/backends/imgui_impl_vulkan.cpp
index d499ecb..1d2d8a1 100644
--- a/backends/imgui_impl_vulkan.cpp
+++ b/backends/imgui_impl_vulkan.cpp
@@ -26,6 +26,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
+// 2024-11-27: Vulkan: Make user-provided descriptor pool optional. As a convenience, when setting init_info->DescriptorPoolSize the backend will create one itself. (#8172, #4867)
// 2024-10-07: Vulkan: Changed default texture sampler to Clamp instead of Repeat/Wrap.
// 2024-10-07: Vulkan: Expose selected render state in ImGui_ImplVulkan_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
// 2024-10-07: Vulkan: Compiling with '#define ImTextureID=ImU64' is unnecessary now that dear imgui defaults ImTextureID to u64 instead of void*.
@@ -131,6 +132,7 @@
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdSetViewport) \
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateBuffer) \
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateCommandPool) \
+ IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateDescriptorPool) \
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateDescriptorSetLayout) \
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateFence) \
IMGUI_VULKAN_FUNC_MAP_MACRO(vkCreateFramebuffer) \
@@ -221,6 +223,7 @@
VkPipeline Pipeline;
VkShaderModule ShaderModuleVert;
VkShaderModule ShaderModuleFrag;
+ VkDescriptorPool DescriptorPool;
// Font data
VkSampler FontSampler;
@@ -1010,6 +1013,20 @@
check_vk_result(err);
}
+ if (v->DescriptorPoolSize)
+ {
+ VkDescriptorPoolSize pool_size = { VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, v->DescriptorPoolSize };
+ VkDescriptorPoolCreateInfo pool_info = {};
+ pool_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
+ pool_info.flags = VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT;
+ pool_info.maxSets = v->DescriptorPoolSize;
+ pool_info.poolSizeCount = 1;
+ pool_info.pPoolSizes = &pool_size;
+
+ err = vkCreateDescriptorPool(v->Device, &pool_info, v->Allocator, &bd->DescriptorPool);
+ check_vk_result(err);
+ }
+
if (!bd->PipelineLayout)
{
// Constants: we are using 'vec2 offset' and 'vec2 scale' instead of a full 3d projection matrix
@@ -1048,6 +1065,7 @@
if (bd->DescriptorSetLayout) { vkDestroyDescriptorSetLayout(v->Device, bd->DescriptorSetLayout, v->Allocator); bd->DescriptorSetLayout = VK_NULL_HANDLE; }
if (bd->PipelineLayout) { vkDestroyPipelineLayout(v->Device, bd->PipelineLayout, v->Allocator); bd->PipelineLayout = VK_NULL_HANDLE; }
if (bd->Pipeline) { vkDestroyPipeline(v->Device, bd->Pipeline, v->Allocator); bd->Pipeline = VK_NULL_HANDLE; }
+ if (bd->DescriptorPool) { vkDestroyDescriptorPool(v->Device, bd->DescriptorPool, v->Allocator); bd->DescriptorPool = VK_NULL_HANDLE; }
}
bool ImGui_ImplVulkan_LoadFunctions(PFN_vkVoidFunction(*loader_func)(const char* function_name, void* user_data), void* user_data)
@@ -1110,7 +1128,10 @@
IM_ASSERT(info->PhysicalDevice != VK_NULL_HANDLE);
IM_ASSERT(info->Device != VK_NULL_HANDLE);
IM_ASSERT(info->Queue != VK_NULL_HANDLE);
- IM_ASSERT(info->DescriptorPool != VK_NULL_HANDLE);
+ if (info->DescriptorPool != VK_NULL_HANDLE) // Either DescriptorPool or DescriptorPoolSize must be set, not both!
+ IM_ASSERT(info->DescriptorPoolSize == 0);
+ else
+ IM_ASSERT(info->DescriptorPoolSize > 0);
IM_ASSERT(info->MinImageCount >= 2);
IM_ASSERT(info->ImageCount >= info->MinImageCount);
if (info->UseDynamicRendering == false)
@@ -1159,19 +1180,20 @@
bd->VulkanInitInfo.MinImageCount = min_image_count;
}
-// Register a texture
+// Register a texture by creating a descriptor
// FIXME: This is experimental in the sense that we are unsure how to best design/tackle this problem, please post to https://github.com/ocornut/imgui/pull/914 if you have suggestions.
VkDescriptorSet ImGui_ImplVulkan_AddTexture(VkSampler sampler, VkImageView image_view, VkImageLayout image_layout)
{
ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+ VkDescriptorPool pool = bd->DescriptorPool ? bd->DescriptorPool : v->DescriptorPool;
// Create Descriptor Set:
VkDescriptorSet descriptor_set;
{
VkDescriptorSetAllocateInfo alloc_info = {};
alloc_info.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
- alloc_info.descriptorPool = v->DescriptorPool;
+ alloc_info.descriptorPool = pool;
alloc_info.descriptorSetCount = 1;
alloc_info.pSetLayouts = &bd->DescriptorSetLayout;
VkResult err = vkAllocateDescriptorSets(v->Device, &alloc_info, &descriptor_set);
@@ -1199,7 +1221,8 @@
{
ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
- vkFreeDescriptorSets(v->Device, v->DescriptorPool, 1, &descriptor_set);
+ VkDescriptorPool pool = bd->DescriptorPool ? bd->DescriptorPool : v->DescriptorPool;
+ vkFreeDescriptorSets(v->Device, pool, 1, &descriptor_set);
}
void ImGui_ImplVulkan_DestroyFrameRenderBuffers(VkDevice device, ImGui_ImplVulkan_FrameRenderBuffers* buffers, const VkAllocationCallbacks* allocator)
diff --git a/backends/imgui_impl_vulkan.h b/backends/imgui_impl_vulkan.h
index ca5b4db..8d9e19f 100644
--- a/backends/imgui_impl_vulkan.h
+++ b/backends/imgui_impl_vulkan.h
@@ -62,10 +62,15 @@
#endif
// Initialization data, for ImGui_ImplVulkan_Init()
-// - VkDescriptorPool should be created with VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT,
-// and must contain a pool size large enough to hold an ImGui VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER descriptor.
-// - When using dynamic rendering, set UseDynamicRendering=true and fill PipelineRenderingCreateInfo structure.
// [Please zero-clear before use!]
+// - About descriptor pool:
+// - A VkDescriptorPool should be created with VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT,
+// and must contain a pool size large enough to hold a small number of VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER descriptors.
+// - As an convenience, by setting DescriptorPoolSize > 0 the backend will create one for you.
+// - Current version of the backend use 1 descriptor for the font atlas + as many as additional calls done to ImGui_ImplVulkan_AddTexture().
+// - It is expected that as early as Q1 2025 the backend will use a few more descriptors, so aim at 10 + number of desierd calls to ImGui_ImplVulkan_AddTexture().
+// - About dynamic rendering:
+// - When using dynamic rendering, set UseDynamicRendering=true and fill PipelineRenderingCreateInfo structure.
struct ImGui_ImplVulkan_InitInfo
{
VkInstance Instance;
@@ -73,7 +78,7 @@
VkDevice Device;
uint32_t QueueFamily;
VkQueue Queue;
- VkDescriptorPool DescriptorPool; // See requirements in note above
+ VkDescriptorPool DescriptorPool; // See requirements in note above; ignored if using DescriptorPoolSize > 0
VkRenderPass RenderPass; // Ignored if using dynamic rendering
uint32_t MinImageCount; // >= 2
uint32_t ImageCount; // >= MinImageCount
@@ -83,6 +88,9 @@
VkPipelineCache PipelineCache;
uint32_t Subpass;
+ // (Optional) Set to create internal descriptor pool instead of using DescriptorPool
+ uint32_t DescriptorPoolSize;
+
// (Optional) Dynamic Rendering
// Need to explicitly enable VK_KHR_dynamic_rendering extension to use this, even for Vulkan 1.3.
bool UseDynamicRendering;
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 5a49416..642adfc 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -59,6 +59,9 @@
- Tools: binary_to_compressed_c: added -u8/-u32/-base85 export options.
- Demo: example tree used by Property Editor & Selection demos properly freed
on application closure. (#8158) [@Legulysse]
+- Backends: Vulkan: Make user-provided descriptor pool optional. As a convenience,
+ when setting init_info->DescriptorPoolSize then the backend will create and manage
+ one itself. (#8172, #4867) [@zeux]
- Examples: Win32+DX12: Using a basic free-list allocator to manage multiple
SRV descriptors.
