初始提交: UE5.3项目基础框架

Plugins/CesiumForUnreal/Source/ThirdParty/include/CesiumGltf/ImageAsset.h

@@ -0,0 +1,132 @@
+#pragma once
+
+#include "CesiumGltf/Ktx2TranscodeTargets.h"
+#include "CesiumGltf/Library.h"
+#include "CesiumUtility/SharedAsset.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <optional>
+#include <vector>
+
+namespace CesiumGltf {
+
+/**
+ * @brief The byte range within a buffer where this mip exists.
+ */
+struct CESIUMGLTF_API ImageAssetMipPosition {
+  /**
+   * @brief The byte index where this mip begins.
+   */
+  size_t byteOffset;
+
+  /**
+   * @brief The size in bytes of this mip.
+   */
+  size_t byteSize;
+};
+
+/**
+ * @brief A 2D image asset, including its pixel data. The image may have
+ * mipmaps, and it may be encoded in a GPU compression format.
+ */
+struct CESIUMGLTF_API ImageAsset final
+    : public CesiumUtility::SharedAsset<ImageAsset> {
+  /**
+   * @brief The width of the image in pixels.
+   */
+  int32_t width = 0;
+
+  /**
+   * @brief The height of the image in pixels.
+   */
+  int32_t height = 0;
+
+  /**
+   * @brief The number of channels per pixel.
+   */
+  int32_t channels = 4;
+
+  /**
+   * @brief The number of bytes per channel.
+   */
+  int32_t bytesPerChannel = 1;
+
+  /**
+   * @brief The gpu compressed pixel format for this image or NONE if it is not
+   * compressed.
+   */
+  GpuCompressedPixelFormat compressedPixelFormat =
+      GpuCompressedPixelFormat::NONE;
+
+  /**
+   * @brief The offset of each mip in the pixel data.
+   *
+   * A list of the positions of each mip's data within the overall pixel buffer.
+   * The first element will be the full image, the second will be the second
+   * biggest and etc. If this is empty, assume the entire buffer is a single
+   * image, the mip map will need to be generated on the client in this case.
+   */
+  std::vector<ImageAssetMipPosition> mipPositions;
+
+  /**
+   * @brief The pixel data.
+   *
+   * This will be the raw pixel data when compressedPixelFormat is std::nullopt.
+   * Otherwise, this buffer will store the compressed pixel data in the
+   * specified format.
+   *
+   * If mipPositions is not empty, this buffer will contains multiple mips
+   * back-to-back.
+   *
+   * When this is an uncompressed texture:
+   * -The pixel data is consistent with the
+   *  [stb](https://github.com/nothings/stb) image library.
+   *
+   * -For a correctly-formed image, the size of the array will be
+   *  `width * height * channels * bytesPerChannel` bytes. There is no
+   *  padding between rows or columns of the image, regardless of format.
+   *
+   * -The channels and their meaning are as follows:
+   *
+   * | Number of Channels | Channel Order and Meaning |
+   * |--------------------|---------------------------|
+   * | 1                  | grey                      |
+   * | 2                  | grey, alpha               |
+   * | 3                  | red, green, blue          |
+   * | 4                  | red, green, blue, alpha   |
+   */
+  std::vector<std::byte> pixelData;
+
+  /**
+   * @brief The effective size of this image, in bytes, for estimating resource
+   * usage for caching purposes.
+   *
+   * When this value is less than zero (the default), the size of this image
+   * should be assumed to equal the size of the {@link pixelData} array. When
+   * it is greater than or equal to zero, the specified size should be used
+   * instead. For example, the overridden size may account for:
+   *   * The `pixelData` being cleared during the load process in order to save
+   * memory.
+   *   * The cost of any renderer resources (e.g., GPU textures) created for
+   * this image.
+   */
+  int64_t sizeBytes = -1;
+
+  /**
+   * @brief Constructs an empty image asset.
+   */
+  ImageAsset() = default;
+
+  /**
+   * @brief Gets the size of this asset, in bytes.
+   *
+   * If {@link sizeBytes} is greater than or equal to zero, it is returned.
+   * Otherwise, the size of the {@link pixelData} array is returned.
+   */
+  int64_t getSizeBytes() const {
+    return this->sizeBytes >= 0 ? this->sizeBytes
+                                : static_cast<int64_t>(this->pixelData.size());
+  }
+};
+} // namespace CesiumGltf