Merge pull request CesiumGS#822 from CesiumGS/refactor-feature-metada…

…ta-textures

Let feature + metadata textures make copies

CHANGES.md

@@ -9,9 +9,12 @@
 
 ##### Additions :tada:
 
+- Added `TextureViewOptions`, which includes the following flags:
+  - `applyKhrTextureTransformExtension` . When true, the view will automatically transform texture coordinates before sampling the texture.
+  - `makeImageCopy`. When true, the view will make its own CPU copy of the image data.
+- Added `TextureView`, which views an arbitrary glTF texture and can be affected by `TextureViewOptions`. `FeatureIdTextureView` and `PropertyTexturePropertyView` now inherit this class.
+- Added `options` parameter to `PropertyTextureView::getPropertyView` and `PropertyTextureView::forEachProperty`, which allow views to be constructed with property-specific options.
 - Added `KhrTextureTransform`, a utility class that parses the `KHR_texture_transform` glTF extension and reports whether it is valid. UVs may be transformed on the CPU using `applyTransform`.
-- Added `applyKhrTextureTransformExtension` to the constructors of `FeatureIdTextureView` and `PropertyTexturePropertyView`. When true, the views will automatically transform texture coordinates before retrieving features and metadata. This is false by default to avoid breaking existing implementations.
-- Added `getTextureTransform` methods to `FeatureIdTextureView` and `PropertyTexturePropertyView`.
 - Added `contains` method to `BoundingSphere`.
 - Added `GlobeRectangle::MAXIMUM` static field.
 - Added `ReferenceCountedThreadSafe` type alias.

CesiumGltf/include/CesiumGltf/FeatureIdTextureView.h

@@ -4,8 +4,8 @@
 #include "CesiumGltf/Image.h"
 #include "CesiumGltf/ImageCesium.h"
 #include "CesiumGltf/KhrTextureTransform.h"
-#include "CesiumGltf/Model.h"
 #include "CesiumGltf/Texture.h"
+#include "CesiumGltf/TextureView.h"
 
 #include <algorithm>
 #include <cmath>
@@ -14,6 +14,9 @@
 #include <optional>
 
 namespace CesiumGltf {
+
+struct Model;
+
 /**
  * @brief The status of a feature ID texture view.
  *
@@ -76,7 +79,7 @@ enum class FeatureIdTextureViewStatus {
  * It provides the ability to sample the feature IDs from the
  * {@link FeatureIdTexture} using texture coordinates.
  */
-class FeatureIdTextureView {
+class FeatureIdTextureView : public TextureView {
 public:
   /**
    * @brief Constructs an uninitialized and invalid view.
@@ -108,7 +111,7 @@ class FeatureIdTextureView {
   FeatureIdTextureView(
       const Model& model,
       const FeatureIdTexture& featureIdTexture,
-      bool applyKhrTextureTransformExtension = false) noexcept;
+      const TextureViewOptions& options = TextureViewOptions()) noexcept;
 
   /**
    * @brief Get the feature ID from the texture at the given texture
@@ -129,73 +132,14 @@ class FeatureIdTextureView {
    */
   FeatureIdTextureViewStatus status() const noexcept { return this->_status; }
 
-  /**
-   * @brief Get the actual feature ID texture.
-   *
-   * This will be nullptr if the feature ID texture view runs into problems
-   * during construction.
-   */
-  const ImageCesium* getImage() const noexcept { return this->_pImage; }
-
-  /**
-   * @brief Get the sampler describing how to sample the data from the
-   * feature ID texture.
-   *
-   * This will be nullptr if the feature ID texture view runs into
-   * problems during construction.
-   */
-  const Sampler* getSampler() const noexcept { return this->_pSampler; }
-
   /**
    * @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; }
 
-  /**
-   * @brief Get the texture coordinate set index for this feature ID
-   * texture.
-   *
-   * If applyKhrTextureTransformExtension is true, and if the feature ID texture
-   * contains the `KHR_texture_transform` extension, this will return the value
-   * from the extension, as it is meant to override the original index. However,
-   * if the extension does not specify a TEXCOORD set index, then the original
-   * index of the feature ID texture is returned.
-   */
-  int64_t getTexCoordSetIndex() const noexcept {
-    if (this->_applyTextureTransform && this->_textureTransform) {
-      return this->_textureTransform->getTexCoordSetIndex().value_or(
-          this->_texCoordSetIndex);
-    }
-    return this->_texCoordSetIndex;
-  }
-
-  /**
-   * @brief Get the KHR_texture_transform for this feature ID texture, if it
-   * exists.
-   *
-   * Even if this view was constructed with applyKhrTextureTransformExtension
-   * set to false, it will save the extension's values, and they may be
-   * retrieved through this function.
-   *
-   * If this view was constructed with applyKhrTextureTransformExtension set to
-   * true, any texture coordinates passed into `getFeatureID` will be
-   * automatically transformed, so there's no need to re-apply the transform
-   * here.
-   */
-  std::optional<KhrTextureTransform> getTextureTransform() const noexcept {
-    return this->_textureTransform;
-  }
-
 private:
   FeatureIdTextureViewStatus _status;
-  int64_t _texCoordSetIndex;
   std::vector<int64_t> _channels;
-
-  const ImageCesium* _pImage;
-  const Sampler* _pSampler;
-
-  bool _applyTextureTransform;
-  std::optional<KhrTextureTransform> _textureTransform;
 };
 } // namespace CesiumGltf