Use variableDescriptorCount to avoid the pipeline recreation.

Instead of create the graphics pipelines with fixed amount of texture descriptor sets, use variable descriptor count to create pipelines only once and only re-allocate the descriptor set. This can make the asset loading time faster.
stripe2933 · Jan 21, 2025 · 9ef3682 · 9ef3682
1 parent 1d8da85
commit 9ef3682
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Showing 4 changed files with 25 additions and 35 deletions.
diff --git a/README.md b/README.md
@@ -110,6 +110,7 @@ The extensions and feature used in this application are quite common in the mode
     - `bufferDeviceAddress`
     - `descriptorIndexing`
     - `descriptorBindingSampledImageUpdateAfterBind`
+    - `descriptorBindingVariableDescriptorCount`
     - `runtimeDescriptorArray`
     - `storageBuffer8BitAccess`
     - `uniformAndStorageBuffer8BitAccess`

diff --git a/impl/vulkan/Gpu.cpp b/impl/vulkan/Gpu.cpp
@@ -198,6 +198,7 @@ auto vk_gltf_viewer::vulkan::Gpu::createDevice() -> vk::raii::Device {
             .setBufferDeviceAddress(true)
             .setDescriptorIndexing(true)
             .setDescriptorBindingSampledImageUpdateAfterBind(true)
+            .setDescriptorBindingVariableDescriptorCount(true)
             .setRuntimeDescriptorArray(true)
             .setStorageBuffer8BitAccess(true)
             .setUniformAndStorageBuffer8BitAccess(true)

diff --git a/interface/vulkan/SharedData.cppm b/interface/vulkan/SharedData.cppm
@@ -42,7 +42,7 @@ namespace vk_gltf_viewer::vulkan {
         SingleTexelSampler singleTexelSampler { gpu.device };
 
         // Descriptor set layouts.
-        dsl::Asset assetDescriptorSetLayout { gpu.device, 1 }; // TODO: set proper initial texture count.
+        dsl::Asset assetDescriptorSetLayout { gpu.device };
         dsl::ImageBasedLighting imageBasedLightingDescriptorSetLayout { gpu.device, cubemapSampler, brdfLutSampler };
         dsl::Scene sceneDescriptorSetLayout { gpu.device };
         dsl::Skybox skyboxDescriptorSetLayout { gpu.device, cubemapSampler };
@@ -73,7 +73,6 @@ namespace vk_gltf_viewer::vulkan {
         std::variant<ag::Swapchain, std::reference_wrapper<ag::Swapchain>> imGuiSwapchainAttachmentGroup = getImGuiSwapchainAttachmentGroup();
 
         // Descriptor pools.
-        vk::raii::DescriptorPool textureDescriptorPool = createTextureDescriptorPool();
         vk::raii::DescriptorPool descriptorPool = createDescriptorPool();
 
         // Descriptor sets.
@@ -86,9 +85,6 @@ namespace vk_gltf_viewer::vulkan {
             : gpu { gpu }
             , swapchainExtent { swapchainExtent }
             , swapchainImages { swapchainImages } {
-            std::tie(assetDescriptorSet)
-                = vku::allocateDescriptorSets(*gpu.device, *textureDescriptorPool, std::tie(
-                    assetDescriptorSetLayout));
             std::tie(sceneDescriptorSet, imageBasedLightingDescriptorSet, skyboxDescriptorSet)
                 = vku::allocateDescriptorSets(*gpu.device, *descriptorPool, std::tie(
                     sceneDescriptorSetLayout,
@@ -152,25 +148,16 @@ namespace vk_gltf_viewer::vulkan {
         }
 
         void updateTextureCount(std::uint32_t textureCount) {
-            if (assetDescriptorSetLayout.descriptorCounts[2] == textureCount) {
-                // If texture count is same, descriptor set layouts, pipeline layouts and pipelines doesn't have to be recreated.
-                return;
-            }
-
-            // Following pipelines are dependent to the assetDescriptorSetLayout.
-            depthRenderer.reset();
-            maskDepthPipelines.clear();
-            jumpFloodSeedRenderer.reset();
-            maskJumpFloodSeedPipelines.clear();
-            primitivePipelines.clear();
-            unlitPrimitivePipelines.clear();
-
-            assetDescriptorSetLayout = { gpu.device, textureCount };
-            primitivePipelineLayout = { gpu.device, std::tie(imageBasedLightingDescriptorSetLayout, assetDescriptorSetLayout, sceneDescriptorSetLayout) };
-            primitiveNoShadingPipelineLayout = { gpu.device, std::tie(assetDescriptorSetLayout, sceneDescriptorSetLayout) };
-
-            textureDescriptorPool = createTextureDescriptorPool();
-            std::tie(assetDescriptorSet) = vku::allocateDescriptorSets(*gpu.device, *textureDescriptorPool, std::tie(assetDescriptorSetLayout));
+            (*gpu.device).freeDescriptorSets(*descriptorPool, assetDescriptorSet);
+            assetDescriptorSet = decltype(assetDescriptorSet) { vku::unsafe, (*gpu.device).allocateDescriptorSets(vk::StructureChain {
+                vk::DescriptorSetAllocateInfo {
+                    *descriptorPool,
+                    *assetDescriptorSetLayout,
+                },
+                vk::DescriptorSetVariableDescriptorCountAllocateInfo {
+                    vk::ArrayProxyNoTemporaries<const std::uint32_t> { textureCount },
+                }
+            }.get())[0] };
         }
 
     private:
@@ -195,12 +182,13 @@ namespace vk_gltf_viewer::vulkan {
             }
         }
 
-        [[nodiscard]] auto createTextureDescriptorPool() const -> vk::raii::DescriptorPool {
-            return { gpu.device, getPoolSizes(assetDescriptorSetLayout).getDescriptorPoolCreateInfo(vk::DescriptorPoolCreateFlagBits::eUpdateAfterBind) };
-        }
-
         [[nodiscard]] auto createDescriptorPool() const -> vk::raii::DescriptorPool {
-            return { gpu.device, getPoolSizes(imageBasedLightingDescriptorSetLayout, sceneDescriptorSetLayout, skyboxDescriptorSetLayout).getDescriptorPoolCreateInfo() };
+            return { gpu.device, getPoolSizes(
+                assetDescriptorSetLayout,
+                imageBasedLightingDescriptorSetLayout,
+                sceneDescriptorSetLayout,
+                skyboxDescriptorSetLayout).getDescriptorPoolCreateInfo(
+                    vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet | vk::DescriptorPoolCreateFlagBits::eUpdateAfterBind) };
         }
     };
 }
diff --git a/interface/vulkan/descriptor_set_layout/Asset.cppm b/interface/vulkan/descriptor_set_layout/Asset.cppm
@@ -6,20 +6,20 @@ export import vulkan_hpp;
 
 namespace vk_gltf_viewer::vulkan::dsl {
     export struct Asset : vku::DescriptorSetLayout<vk::DescriptorType::eStorageBuffer, vk::DescriptorType::eStorageBuffer, vk::DescriptorType::eCombinedImageSampler> {
-        Asset(const vk::raii::Device &device [[clang::lifetimebound]], std::uint32_t textureCount)
+        explicit Asset(const vk::raii::Device &device [[clang::lifetimebound]])
             : DescriptorSetLayout { device, vk::StructureChain {
                 vk::DescriptorSetLayoutCreateInfo {
                     vk::DescriptorSetLayoutCreateFlagBits::eUpdateAfterBindPool,
                     vku::unsafeProxy(getBindings(
                         { 1, vk::ShaderStageFlagBits::eVertex },
                         { 1, vk::ShaderStageFlagBits::eVertex | vk::ShaderStageFlagBits::eFragment },
-                        { textureCount, vk::ShaderStageFlagBits::eFragment })),
+                        { 126, vk::ShaderStageFlagBits::eFragment })),
                 },
                 vk::DescriptorSetLayoutBindingFlagsCreateInfo {
-                    vku::unsafeProxy({
-                        vk::DescriptorBindingFlags{},
-                        vk::DescriptorBindingFlags{},
-                        vk::Flags { vk::DescriptorBindingFlagBits::eUpdateAfterBind },
+                    vku::unsafeProxy<vk::DescriptorBindingFlags>({
+                        {},
+                        {},
+                        vk::DescriptorBindingFlagBits::eUpdateAfterBind | vk::DescriptorBindingFlagBits::eVariableDescriptorCount,
                     }),
                 },
             }.get() } { }