Add PropertyAttributeView and PropertyAttributePropertyView.

CHANGES.md

@@ -28,6 +28,9 @@
 - Added `PropertyViewStatus`, which defines public `static const` values for various property errors.
 - Added `PropertyTableViewStatus` to indicate whether a `PropertyTableView` is valid.
 - Added `PropertyComponentType` to reflect the values of `componentType` in a `ClassProperty` from `EXT_structural_metadata`.
+- Added `PropertyAttributeView`, which views a `PropertyAttribute` in `EXT_structural_metadata`.
+- Added `PropertyAttributePropertyView`, which views a `PropertyAttributeProperty` in `EXT_structural_metadata`.
+- Added `PropertyAttributePropertyViewStatus`, which reflects the sattus of a `PropertyAttributePropertyView`.
 
 ### v0.27.0 - 2023-09-01
 

CesiumGltf/include/CesiumGltf/AccessorView.h

@@ -403,7 +403,7 @@ createAccessorView(
   }
   // TODO Print a warning here???
   return callback(AccessorView<AccessorTypes::SCALAR<TElement>>(
-      AccessorViewStatus::InvalidComponentType));
+      AccessorViewStatus::InvalidType));
 }
 } // namespace CesiumImpl
 

CesiumGltf/include/CesiumGltf/PropertyAttributePropertyView.h

@@ -0,0 +1,364 @@
+#pragma once
+
+#include "CesiumGltf/AccessorView.h"
+#include "CesiumGltf/PropertyAttributeProperty.h"
+#include "CesiumGltf/PropertyTransformations.h"
+#include "CesiumGltf/PropertyTypeTraits.h"
+#include "CesiumGltf/PropertyView.h"
+
+#include <cassert>
+#include <cmath>
+#include <cstdint>
+
+namespace CesiumGltf {
+/**
+ * @brief Indicates the status of a property attribute property view.
+ *
+ * The {@link PropertyAttributePropertyView} constructor always completes
+ * successfully. However it may not always reflect the actual content of the
+ * corresponding property texture property. This enumeration provides the
+ * reason.
+ */
+class PropertyAttributePropertyViewStatus : public PropertyViewStatus {
+public:
+  /**
+   * @brief This property view was initialized from an invalid
+   * {@link PropertyAttribute}.
+   */
+  static const int ErrorInvalidPropertyAttribute = 13;
+
+  /**
+   * @brief This property view is associated with a {@link ClassProperty} of an
+   * unsupported type.
+   */
+  static const int ErrorUnsupportedProperty = 14;
+
+  /**
+   * @brief This property view was initialized with a primitive that does not
+   * contain the specified attribute.
+   */
+  static const int ErrorMissingAttribute = 15;
+
+  /**
+   * @brief This property view's attribute does not have a valid accessor index.
+   */
+  static const int ErrorInvalidAccessor = 16;
+
+  /**
+   * @brief This property view's type does not match the type of the accessor it
+   * uses.
+   */
+  static const int ErrorAccessorTypeMismatch = 17;
+
+  /**
+   * @brief This property view's component type does not match the type of the
+   * accessor it uses.
+   */
+  static const int ErrorAccessorComponentTypeMismatch = 18;
+
+  /**
+   * @brief This property view's normalization does not match the normalization
+   * of the accessor it uses.
+   */
+  static const int ErrorAccessorNormalizationMismatch = 19;
+
+  /**
+   * @brief This property view uses an accessor that does not have a valid
+   * buffer view index.
+   */
+  static const int ErrorInvalidBufferView = 20;
+
+  /**
+   * @brief This property view uses a buffer view that does not have a valid
+   * buffer index.
+   */
+  static const int ErrorInvalidBuffer = 21;
+
+  /**
+   * @brief This property view uses an accessor that points outside the bounds
+   * of its target buffer view.
+   */
+  static const PropertyViewStatusType ErrorAccessorOutOfBounds = 22;
+
+  /**
+   * @brief This property view uses a buffer view that points outside the bounds
+   * of its target buffer.
+   */
+  static const PropertyViewStatusType ErrorBufferViewOutOfBounds = 23;
+};
+
+/**
+ * @brief A view of the data specified by a {@link PropertyAttributeProperty}.
+ *
+ * Ideally, property attribute properties can be initialized as vertex
+ * attributes in the target rendering context. However, some runtime engines do
+ * not allow custom vertex attributes. To compensate, this view can be used to
+ * sample the property attributes property via vertex index.
+ *
+ * @tparam ElementType The type of the elements represented in the property view
+ * @tparam Normalized Whether or not the property is normalized. If normalized,
+ * the elements can be retrieved as normalized floating-point numbers, as
+ * opposed to their integer values.
+ */
+template <typename ElementType, bool Normalized = false>
+class PropertyAttributePropertyView;
+
+/**
+ * @brief A view of the non-normalized data specified by a
+ * {@link PropertyAttributeProperty}.
+ *
+ * Ideally, property attribute properties can be initialized as vertex
+ * attributes in the target rendering context. However, some runtime engines do
+ * not allow custom vertex attributes. This view can be used instead to sample
+ * the property attributes property via vertex index.
+ *
+ * @tparam ElementType The type of the elements represented in the property view
+ */
+template <typename ElementType>
+class PropertyAttributePropertyView<ElementType, false>
+    : public PropertyView<ElementType, false> {
+public:
+  /**
+   * @brief Constructs an invalid instance for a non-existent property.
+   */
+  PropertyAttributePropertyView() noexcept
+      : PropertyView<ElementType, false>(), _accessor{} {}
+
+  /**
+   * @brief Constructs an invalid instance for an erroneous property.
+   *
+   * @param status The code from {@link PropertyAttributePropertyViewStatus} indicating the error with the property.
+   */
+  PropertyAttributePropertyView(PropertyViewStatusType status) noexcept
+      : PropertyView<ElementType, false>(status), _accessor{} {
+    assert(
+        this->_status != PropertyAttributePropertyViewStatus::Valid &&
+        "An empty property view should not be constructed with a valid status");
+  }
+
+  /**
+   * @brief Construct a view of the data specified by a {@link PropertyAttributeProperty}.
+   *
+   * @param property The {@link PropertyAttributeProperty}
+   * @param classProperty The {@link ClassProperty} this property conforms to.
+   * @param accsesorView The {@link AccessorView} for the data that this property is
+   * associated with.
+   */
+  PropertyAttributePropertyView(
+      const PropertyAttributeProperty& property,
+      const ClassProperty& classProperty,
+      const AccessorView<ElementType>& accessorView) noexcept
+      : PropertyView<ElementType, false>(classProperty, property),
+        _accessor{accessorView} {}
+
+  /**
+   * @brief Gets the value of the property for the given texture coordinates
+   * with all value transforms applied. That is, if the property specifies an
+   * offset and scale, they will be applied to the value before the value is
+   * returned.
+   *
+   * If this property has a specified "no data" value, this will return the
+   * property's default value for any elements that equal this "no data" value.
+   * If the property did not specify a default value, this returns std::nullopt.
+   *
+   * @param index The vertex index.
+   *
+   * @return The value of the property for the given vertex, or std::nullopt if
+   * it matches the "no data" value
+   */
+  std::optional<ElementType> get(int64_t index) const noexcept {
+    ElementType value = getRaw(index);
+
+    if (value == this->noData()) {
+      return this->defaultValue();
+    }
+
+    return transformValue(value, this->offset(), this->scale());
+  }
+
+  /**
+   * @brief Gets the raw value of the property for the given vertex index.
+   *
+   * If this property has a specified "no data" value, the raw value will still
+   * be returned, even if it equals the "no data" value.
+   *
+   * @param index The vertex index.
+   *
+   * @return The value of the property for the given vertex.
+   */
+  ElementType getRaw(int64_t index) const noexcept {
+    assert(
+        this->_status == PropertyAttributePropertyViewStatus::Valid &&
+        "Check the status() first to make sure view is valid");
+    assert(
+        size() > 0 &&
+        "Check the size() of the view to make sure it's not empty");
+    assert(index >= 0 && "index must be non-negative");
+    assert(index < size() && "index must be less than size");
+
+    return _accessor[index];
+  }
+
+  /**
+   * @brief Get the number of elements in this PropertyAttributePropertyView.
+   * If the view is valid, this returns the count of the elements in the
+   * attribute's accessor. Otherwise, this returns 0.
+   *
+   * @return The number of elements in this PropertyAttributePropertyView.
+   */
+  int64_t size() const noexcept {
+    if (this->_status != PropertyAttributePropertyViewStatus::Valid) {
+      return 0;
+    }
+
+    return _accessor.size();
+  }
+
+private:
+  AccessorView<ElementType> _accessor;
+};
+
+/**
+ * @brief A view of the normalized data specified by a
+ * {@link PropertyAttributeProperty}.
+ *
+ * Ideally, property attribute properties can be initialized as vertex
+ * attributes in the target rendering context. However, some runtime engines do
+ * not allow custom vertex attributes. This view can be used instead to sample
+ * the property attributes property via vertex index.
+ *
+ * @tparam ElementType The type of the elements represented in the property view
+ */
+template <typename ElementType>
+class PropertyAttributePropertyView<ElementType, true>
+    : public PropertyView<ElementType, true> {
+private:
+  using NormalizedType = typename TypeToNormalizedType<ElementType>::type;
+
+public:
+  /**
+   * @brief Constructs an invalid instance for a non-existent property.
+   */
+  PropertyAttributePropertyView() noexcept
+      : PropertyView<ElementType, true>(), _accessor{} {}
+
+  /**
+   * @brief Constructs an invalid instance for an erroneous property.
+   *
+   * @param status The code from {@link PropertyAttributePropertyViewStatus} indicating the error with the property.
+   */
+  PropertyAttributePropertyView(PropertyViewStatusType status) noexcept
+      : PropertyView<ElementType, true>(status), _accessor{} {
+    assert(
+        this->_status != PropertyAttributePropertyViewStatus::Valid &&
+        "An empty property view should not be constructed with a valid status");
+  }
+
+  /**
+   * @brief Construct a view of the data specified by a {@link PropertyAttributeProperty}.
+   *
+   * @param property The {@link PropertyAttributeProperty}
+   * @param classProperty The {@link ClassProperty} this property conforms to.
+   * @param accsesorView The {@link AccessorView} for the data that this property is
+   * associated with.
+   */
+  PropertyAttributePropertyView(
+      const PropertyAttributeProperty& property,
+      const ClassProperty& classProperty,
+      const AccessorView<ElementType>& accessorView) noexcept
+      : PropertyView<ElementType, true>(classProperty, property),
+        _accessor{accessorView} {}
+
+  /**
+   * @brief Gets the value of the property for the given texture coordinates
+   * with all value transforms applied. That is, if the property specifies an
+   * offset and scale, they will be applied to the value before the value is
+   * returned.
+   *
+   * If this property has a specified "no data" value, this will return the
+   * property's default value for any elements that equal this "no data" value.
+   * If the property did not specify a default value, this returns std::nullopt.
+   *
+   * @param index The vertex index.
+   *
+   * @return The value of the property for the given vertex, or std::nullopt if
+   * it matches the "no data" value
+   */
+  std::optional<NormalizedType> get(int64_t index) const noexcept {
+    ElementType value = getRaw(index);
+
+    if (value == this->noData()) {
+      return this->defaultValue();
+    }
+
+    if constexpr (IsMetadataScalar<ElementType>::value) {
+      return transformValue<NormalizedType>(
+          normalize<ElementType>(value),
+          this->offset(),
+          this->scale());
+    }
+
+    if constexpr (IsMetadataVecN<ElementType>::value) {
+      constexpr glm::length_t N = ElementType::length();
+      using T = typename ElementType::value_type;
+      using NormalizedT = typename NormalizedType::value_type;
+      return transformValue<glm::vec<N, NormalizedT>>(
+          normalize<N, T>(value),
+          this->offset(),
+          this->scale());
+    }
+
+    if constexpr (IsMetadataMatN<ElementType>::value) {
+      constexpr glm::length_t N = ElementType::length();
+      using T = typename ElementType::value_type;
+      using NormalizedT = typename NormalizedType::value_type;
+      return transformValue<glm::mat<N, N, NormalizedT>>(
+          normalize<N, T>(value),
+          this->offset(),
+          this->scale());
+    }
+  }
+
+  /**
+   * @brief Gets the raw value of the property for the given vertex index.
+   *
+   * If this property has a specified "no data" value, the raw value will still
+   * be returned, even if it equals the "no data" value.
+   *
+   * @param index The vertex index.
+   *
+   * @return The value of the property for the given vertex.
+   */
+  ElementType getRaw(int64_t index) const noexcept {
+    assert(
+        this->_status == PropertyAttributePropertyViewStatus::Valid &&
+        "Check the status() first to make sure view is valid");
+    assert(
+        size() > 0 &&
+        "Check the size() of the view to make sure it's not empty");
+    assert(index >= 0 && "index must be non-negative");
+    assert(index < size() && "index must be less than size");
+
+    return _accessor[index];
+  }
+
+  /**
+   * @brief Get the number of elements in this PropertyAttributePropertyView.
+   * If the view is valid, this returns the count of the elements in the
+   * attribute's accessor. Otherwise, this returns 0.
+   *
+   * @return The number of elements in this PropertyAttributePropertyView.
+   */
+  int64_t size() const noexcept {
+    if (this->_status != PropertyAttributePropertyViewStatus::Valid) {
+      return 0;
+    }
+
+    return _accessor.size();
+  }
+
+private:
+  AccessorView<ElementType> _accessor;
+};
+
+} // namespace CesiumGltf