初始提交: UE5.3项目基础框架

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

@@ -0,0 +1,136 @@
+#pragma once
+
+#include "CesiumGltf/FeatureIdTexture.h"
+#include "CesiumGltf/TextureView.h"
+
+#include <cstdint>
+
+namespace CesiumGltf {
+
+struct Model;
+
+/**
+ * @brief The status of a feature ID texture view.
+ *
+ * The {@link FeatureIdTextureView} constructor always completes successfully,
+ * but it may not always reflect the actual content of the
+ * {@link FeatureIdTexture}. This enumeration provides the reason.
+ */
+enum class FeatureIdTextureViewStatus {
+  /**
+   * @brief This view is valid and ready to use.
+   */
+  Valid,
+
+  /**
+   * @brief This view has not yet been initialized.
+   */
+  ErrorUninitialized,
+
+  /**
+   * @brief This feature ID texture has a texture index that doesn't exist in
+   * the glTF.
+   */
+  ErrorInvalidTexture,
+
+  /**
+   * @brief This feature ID texture has an image index that doesn't exist in
+   * the glTF.
+   */
+  ErrorInvalidImage,
+
+  /**
+   * @brief This feature ID texture has a sampler index that doesn't exist in
+   * the glTF.
+   */
+  ErrorInvalidSampler,
+
+  /**
+   * @brief This feature ID texture has an empty image.
+   */
+  ErrorEmptyImage,
+
+  /**
+   * @brief The image for this feature ID texture has channels that take up more
+   * than a byte. Only single-byte channels are supported.
+   */
+  ErrorInvalidImageBytesPerChannel,
+
+  /**
+   * @brief The channels of this feature ID texture property are invalid.
+   * Channels must be in the range 0-3, with a minimum of one channel. Although
+   * more than four channels can be defined for specialized texture
+   * formats, this view only supports a maximum of four channels.
+   */
+  ErrorInvalidChannels
+};
+
+/**
+ * @brief A view on the image data of {@link FeatureIdTexture}.
+ *
+ * It provides the ability to sample the feature IDs from the
+ * {@link FeatureIdTexture} using texture coordinates.
+ */
+class FeatureIdTextureView : public TextureView {
+public:
+  /**
+   * @brief Constructs an uninitialized and invalid view.
+   */
+  FeatureIdTextureView() noexcept;
+
+  /**
+   * @brief Construct a view of the data specified by a {@link FeatureIdTexture}.
+   *
+   * A feature ID texture may contain the `KHR_texture_transform` extension,
+   * which transforms the texture coordinates used to sample the texture. The
+   * extension may also override the TEXCOORD set index that was originally
+   * specified by the feature ID texture.
+   *
+   * If a view is constructed with applyKhrTextureTransformExtension set to
+   * true, the view will automatically apply the texture transform to any UV
+   * coordinates used to sample the texture. If the extension defines its own
+   * TEXCOORD set index, it will override the original value.
+   *
+   * Otherwise, if the flag is set to false, UVs will not be transformed and
+   * the original TEXCOORD set index will be preserved. The extension's values
+   * may still be retrieved using getTextureTransform, if desired.
+   *
+   * @param model The glTF in which to look for the feature ID texture's data.
+   * @param featureIdTexture The feature ID texture to create a view for.
+   * @param options The set of options to use for this `FeatureIdTextureView`.
+   */
+  FeatureIdTextureView(
+      const Model& model,
+      const FeatureIdTexture& featureIdTexture,
+      const TextureViewOptions& options = TextureViewOptions()) noexcept;
+
+  /**
+   * @brief Get the feature ID from the texture at the given texture
+   * coordinates. If the texture is somehow invalid, this returns -1.
+   *
+   * @param u The u-component of the texture coordinates. Must be within
+   * [0.0, 1.0].
+   * @param v The v-component of the texture coordinates. Must be within
+   * [0.0, 1.0].
+   * @return The feature ID at the nearest pixel to the texture coordinates.
+   */
+  int64_t getFeatureID(double u, double v) const noexcept;
+
+  /**
+   * @brief Get the status of this view.
+   *
+   * If invalid, it will not be safe to sample feature IDs from this view.
+   */
+  FeatureIdTextureViewStatus status() const noexcept { return this->_status; }
+
+  /**
+   * @brief Get the channels of this feature ID texture. The channels represent
+   * the bytes of the actual feature ID, in little-endian order.
+   */
+  std::vector<int64_t> getChannels() const noexcept { return this->_channels; }
+
+private:
+  FeatureIdTextureViewStatus _status;
+  std::vector<int64_t> _channels;
+};
+} // namespace CesiumGltf