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framework/core/descriptor_set.h

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+/* Copyright (c) 2019-2025, Arm Limited and Contributors
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 the "License";
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "common/helpers.h"
+#include "common/vk_common.h"
+
+namespace vkb
+{
+class DescriptorSetLayout;
+class DescriptorPool;
+
+namespace core
+{
+template <vkb::BindingType bindingType>
+class Device;
+using DeviceC = Device<vkb::BindingType::C>;
+}        // namespace core
+
+/**
+ * @brief A descriptor set handle allocated from a \ref DescriptorPool.
+ *        Destroying the handle has no effect, as the pool manages the lifecycle of its descriptor sets.
+ *
+ *        Keeps track of what bindings were written to prevent a double write.
+ */
+class DescriptorSet
+{
+  public:
+	/**
+	 * @brief Constructs a descriptor set from buffer infos and image infos
+	 *        Implicitly calls prepare()
+	 * @param device A valid Vulkan device
+	 * @param descriptor_set_layout The Vulkan descriptor set layout this descriptor set has
+	 * @param descriptor_pool The Vulkan descriptor pool the descriptor set is allocated from
+	 * @param buffer_infos The descriptors that describe buffer data
+	 * @param image_infos The descriptors that describe image data
+	 */
+	DescriptorSet(vkb::core::DeviceC                       &device,
+	              const DescriptorSetLayout                &descriptor_set_layout,
+	              DescriptorPool                           &descriptor_pool,
+	              const BindingMap<VkDescriptorBufferInfo> &buffer_infos = {},
+	              const BindingMap<VkDescriptorImageInfo>  &image_infos  = {});
+
+	DescriptorSet(const DescriptorSet &) = delete;
+
+	DescriptorSet(DescriptorSet &&other);
+
+	// The descriptor set handle is managed by the pool, and will be destroyed when the pool is reset
+	~DescriptorSet() = default;
+
+	DescriptorSet &operator=(const DescriptorSet &) = delete;
+
+	DescriptorSet &operator=(DescriptorSet &&) = delete;
+
+	/**
+	 * @brief Resets the DescriptorSet state
+	 *        Optionally prepares a new set of buffer infos and/or image infos
+	 * @param new_buffer_infos A map of buffer descriptors and their respective bindings
+	 * @param new_image_infos A map of image descriptors and their respective bindings
+	 */
+	void reset(const BindingMap<VkDescriptorBufferInfo> &new_buffer_infos = {},
+	           const BindingMap<VkDescriptorImageInfo>  &new_image_infos  = {});
+
+	/**
+	 * @brief Updates the contents of the DescriptorSet by performing the write operations
+	 * @param bindings_to_update If empty. we update all bindings. Otherwise, only write the specified bindings if they haven't already been written
+	 */
+	void update(const std::vector<uint32_t> &bindings_to_update = {});
+
+	/**
+	 * @brief Applies pending write operations without updating the state
+	 */
+	void apply_writes() const;
+
+	const DescriptorSetLayout &get_layout() const;
+
+	VkDescriptorSet get_handle() const;
+
+	BindingMap<VkDescriptorBufferInfo> &get_buffer_infos();
+
+	BindingMap<VkDescriptorImageInfo> &get_image_infos();
+
+  protected:
+	/**
+	 * @brief Prepares the descriptor set to have its contents updated by loading a vector of write operations
+	 *        Cannot be called twice during the lifetime of a DescriptorSet
+	 */
+	void prepare();
+
+  private:
+	vkb::core::DeviceC &device;
+
+	const DescriptorSetLayout &descriptor_set_layout;
+
+	DescriptorPool &descriptor_pool;
+
+	BindingMap<VkDescriptorBufferInfo> buffer_infos;
+
+	BindingMap<VkDescriptorImageInfo> image_infos;
+
+	VkDescriptorSet handle{VK_NULL_HANDLE};
+
+	// The list of write operations for the descriptor set
+	std::vector<VkWriteDescriptorSet> write_descriptor_sets;
+
+	// The bindings of the write descriptors that have had vkUpdateDescriptorSets since the last call to update().
+	// Each binding number is mapped to a hash of the binding description that it will be updated to.
+	std::unordered_map<uint32_t, size_t> updated_bindings;
+};
+}        // namespace vkb