Reduce Vulkan animated RT buffer churn

Author: anirul

frame/vulkan/buffer.cpp

@@ -116,6 +116,27 @@ void Buffer::Copy(const std::vector<std::uint8_t>& vector) const
     IncrementGeneration(generation_);
 }
 
+bool Buffer::CopyRange(
+    std::size_t offset,
+    const std::vector<std::uint8_t>& vector) const
+{
+    if (vector.empty())
+    {
+        return false;
+    }
+    if (offset > data_.size() || vector.size() > data_.size() - offset)
+    {
+        throw std::out_of_range("Buffer::CopyRange exceeds destination size.");
+    }
+    if (std::memcmp(data_.data() + offset, vector.data(), vector.size()) == 0)
+    {
+        return false;
+    }
+    std::memcpy(data_.data() + offset, vector.data(), vector.size());
+    IncrementGeneration(generation_);
+    return true;
+}
+
 void Buffer::Clear() const
 {
     const bool already_zero = std::all_of(

frame/vulkan/buffer.h

@@ -20,6 +20,9 @@ class Buffer : public frame::BufferInterface
     void Copy(const std::vector<float>& vector) const override;
     void Copy(const std::vector<std::uint32_t>& vector) const override;
     void Copy(const std::vector<std::uint8_t>& vector) const override;
+    bool CopyRange(
+        std::size_t offset,
+        const std::vector<std::uint8_t>& vector) const;
     void Clear() const override;
     std::size_t GetSize() const override;
     void BindBase(int /*binding*/) const override

frame/vulkan/buffer_resources.cpp

@@ -216,6 +216,58 @@ bool BufferResourceManager::UpdateStorageBuffer(
     return true;
 }
 
+bool BufferResourceManager::UpdateStorageBufferRange(
+    const std::string& name,
+    const std::vector<std::uint8_t>& bytes,
+    std::size_t offset_bytes)
+{
+    if (bytes.empty())
+    {
+        return false;
+    }
+    auto it = storage_buffer_indices_.find(name);
+    if (it == storage_buffer_indices_.end())
+    {
+        return false;
+    }
+    auto& resource = storage_buffers_[it->second];
+    if (!resource.buffer || resource.size == 0)
+    {
+        return false;
+    }
+    if (offset_bytes > static_cast<std::size_t>(resource.size) ||
+        bytes.size() >
+            static_cast<std::size_t>(resource.size) - offset_bytes)
+    {
+        (*logger_)->warn(
+            "Storage buffer '{}' range update [{}..{}) exceeds resource size {}.",
+            name,
+            offset_bytes,
+            offset_bytes + bytes.size(),
+            static_cast<std::size_t>(resource.size));
+        return false;
+    }
+
+    vk::UniqueDeviceMemory staging_memory;
+    auto staging_buffer = memory_manager_->CreateBuffer(
+        bytes.size(),
+        vk::BufferUsageFlagBits::eTransferSrc,
+        vk::MemoryPropertyFlagBits::eHostVisible |
+            vk::MemoryPropertyFlagBits::eHostCoherent,
+        staging_memory);
+    void* mapped = device_.mapMemory(
+        *staging_memory, 0, bytes.size());
+    std::memcpy(mapped, bytes.data(), bytes.size());
+    device_.unmapMemory(*staging_memory);
+    command_queue_->CopyBuffer(
+        *staging_buffer,
+        *resource.buffer,
+        static_cast<vk::DeviceSize>(bytes.size()),
+        0,
+        static_cast<vk::DeviceSize>(offset_bytes));
+    return true;
+}
+
 void BufferResourceManager::BuildUniformBuffers(
     std::size_t count,
     vk::DeviceSize size_bytes)

frame/vulkan/buffer_resources.h

@@ -39,6 +39,10 @@ class BufferResourceManager
     bool UpdateStorageBuffer(
         const std::string& name,
         const std::vector<std::uint8_t>& bytes);
+    bool UpdateStorageBufferRange(
+        const std::string& name,
+        const std::vector<std::uint8_t>& bytes,
+        std::size_t offset_bytes);
     void BuildUniformBuffers(
         std::size_t count,
         vk::DeviceSize size_bytes);

frame/vulkan/command_queue.cpp

@@ -48,10 +48,14 @@ void CommandQueue::EndOneTime(vk::CommandBuffer command_buffer) const
 }
 
 void CommandQueue::CopyBuffer(
-    vk::Buffer src, vk::Buffer dst, vk::DeviceSize size) const
+    vk::Buffer src,
+    vk::Buffer dst,
+    vk::DeviceSize size,
+    vk::DeviceSize src_offset,
+    vk::DeviceSize dst_offset) const
 {
     auto command_buffer = BeginOneTime();
-    vk::BufferCopy copy_region(0, 0, size);
+    vk::BufferCopy copy_region(src_offset, dst_offset, size);
     command_buffer.copyBuffer(src, dst, copy_region);
     EndOneTime(command_buffer);
 }

frame/vulkan/command_queue.h

@@ -34,7 +34,12 @@ class CommandQueue
         }
     }
 
-    void CopyBuffer(vk::Buffer src, vk::Buffer dst, vk::DeviceSize size) const;
+    void CopyBuffer(
+        vk::Buffer src,
+        vk::Buffer dst,
+        vk::DeviceSize size,
+        vk::DeviceSize src_offset = 0,
+        vk::DeviceSize dst_offset = 0) const;
     void CopyBufferToImage(
         vk::Buffer buffer,
         vk::Image image,