diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 43e6e0193b..fe1eefebf2 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -23,7 +23,7 @@ jobs:
steps:
# Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
- - uses: actions/checkout@v2
+ - uses: actions/checkout@v4
# Build spec targets
- name: spec-generate
@@ -32,7 +32,7 @@ jobs:
make Specification.html Specification.pdf
- name: Archive generated files
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v4
with:
name: spec-outputs
path: |
diff --git a/extensions/2.0/Vendor/EXT_implicit_cylinder_region/README.md b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/README.md
new file mode 100644
index 0000000000..b7a9b39e43
--- /dev/null
+++ b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/README.md
@@ -0,0 +1,110 @@
+# EXT_implicit_cylinder_region
+
+## Contributors
+
+- Janine Liu, Cesium
+- Sean Lilley, Cesium
+
+## Status
+
+Draft
+
+## Dependencies
+
+Written against the glTF 2.0 specification. Depends on the [`KHR_implicit_shapes`](https://github.com/eoineoineoin/glTF/tree/refs/heads/collisionShapeMerge/extensions/2.0/Khronos/KHR_implicit_shapes) extension.
+
+## Overview
+
+This extension defines a cylinder-conforming region as an additional shape type for the `KHR_implicit_shapes` extension. These regions are useful for visualizing real-world data that has been captured by cylindrical sensors.
+
+`EXT_implicit_cylinder_region` extends the `shape` object in `KHR_implicit_shapes`. The `shape.type` should be set to `"cylinder region"`. The properties define a region following the surface of a cylinder between two different radius values.
+
+The cylinder does not need to be completely represented by the volume—for instance, the region may be hollow inside like a tube. However, an inner radius of `0` results in a completely solid cylinder.
+
+### Details
+
+The cylinder is centered at the origin, where the radius is measured along the `x` and `z` axes. The `height` of the cylinder is aligned with the `y` axis.
+
+
+
+ |
+ Example
+ |
+
+
+ |
+
+```json
+"extensions": [
+ {
+ "KHR_implicit_shapes": {
+ "shapes": [
+ {
+ "type": "cylinder region",
+ "extensions": {
+ "EXT_implicit_cylinder_region": {
+ "minRadius": 0.5,
+ "maxRadius": 1,
+ "height": 2
+ }
+ }
+ }
+ ]
+ }
+ }
+]
+```
+
+ |
+
+ 
+ |
+
+
+
+A cylinder region may also be confined to a certain angular range. The `minAngle` and `maxAngle` properties define the angles at which the region starts and stops on the cylinder.
+
+Angles are given in radians within the range `[-pi, pi]` and open clockwise around the cylinder (see figure below).
+
+
+
+
+
+ |
+ Example
+ |
+
+
+ |
+
+```json
+"extensions": [
+ {
+ "KHR_implicit_shapes": {
+ "shapes": [
+ {
+ "type": "cylinder region",
+ "extensions": {
+ "EXT_implicit_cylinder_region": {
+ "minRadius": 0.5,
+ "maxRadius": 1,
+ "height": 2,
+ "minAngle": 0,
+ "maxAngle": 3.1415
+ }
+ }
+ }
+ ]
+ }
+ }
+]
+```
+ |
+
+ 
+ |
+
+
+
+## Optional vs. Required
+This extension is required, meaning it should be placed in both the `extensionsUsed` list and `extensionsRequired` list.
diff --git a/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/cylinder-angle.png b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/cylinder-angle.png
new file mode 100644
index 0000000000..839db634dd
Binary files /dev/null and b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/cylinder-angle.png differ
diff --git a/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/half-cylinder.png b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/half-cylinder.png
new file mode 100644
index 0000000000..3d2b728701
Binary files /dev/null and b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/half-cylinder.png differ
diff --git a/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/hollow-cylinder.png b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/hollow-cylinder.png
new file mode 100644
index 0000000000..b47ee174ee
Binary files /dev/null and b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/figures/hollow-cylinder.png differ
diff --git a/extensions/2.0/Vendor/EXT_implicit_cylinder_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_cylinder_region.schema.json b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_cylinder_region.schema.json
new file mode 100644
index 0000000000..3dd6e0d3d3
--- /dev/null
+++ b/extensions/2.0/Vendor/EXT_implicit_cylinder_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_cylinder_region.schema.json
@@ -0,0 +1,48 @@
+{
+ "$schema": "https://json-schema.org/draft/2020-12/schema",
+ "$id": "glTF.KHR_implicit_shapes.shape.EXT_implicit_cylinder_region.schema.json",
+ "title": "EXT_implicit_cylinder_region extension on KHR_implicit_shapes.shape",
+ "type": "object",
+ "description": "Extension of `KHR_implicit_shapes.shape` to represent an implicit cylinder region in a glTF model.",
+ "allOf": [
+ {
+ "$ref": "glTFProperty.schema.json"
+ }
+ ],
+ "properties": {
+ "minRadius": {
+ "type": "number",
+ "description": "The inner radius of the cylinder region along the X and Z axes, in meters.",
+ "minimum": 0
+ },
+ "maxRadius": {
+ "type": "number",
+ "description": "The outer radius of the cylinder region along the X and Z axes, in meters.",
+ "minimum": 0
+ },
+ "height": {
+ "type": "number",
+ "description": "The height of the cylinder in meters along the Y-axis, in meters.",
+ "minimum": 0
+ },
+ "minAngle": {
+ "type": "number",
+ "description": "The minimum angle of the cylinder region in radians. In other words, this is the angle where the cylinder region starts. Must be in the range [-pi, pi].",
+ "minimum": -3.14159265359,
+ "maximum": 3.14159265359,
+ "default": -3.14159265359
+ },
+ "maxAngle": {
+ "type": "number",
+ "description": "The maximum angle of the cylinder region in radians. In other words, this is the angle where the cylinder region ends. Must be in the range [-pi, pi].",
+ "minimum": -3.14159265359,
+ "maximum": 3.14159265359,
+ "default": 3.14159265359
+ }
+ },
+ "required": [
+ "minRadius",
+ "maxRadius",
+ "height"
+ ]
+}
\ No newline at end of file
diff --git a/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/README.md b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/README.md
new file mode 100644
index 0000000000..5024775f63
--- /dev/null
+++ b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/README.md
@@ -0,0 +1,91 @@
+# EXT_implicit_ellipsoid_region
+
+## Contributors
+
+- Janine Liu, Cesium
+- Sean Lilley, Cesium
+
+## Status
+
+Draft
+
+## Dependencies
+
+Written against the glTF 2.0 specification. Depends on the [`KHR_implicit_shapes`](https://github.com/eoineoineoin/glTF/tree/refs/heads/collisionShapeMerge/extensions/2.0/Khronos/KHR_implicit_shapes) extension.
+
+## Overview
+
+This extension defines an ellipsoid-conforming region as an additional shape type for the `KHR_implicit_shapes` extension. These regions are commonly used in geospatial applications to describe volumes that conform to the curvature of the Earth, or other bodies.
+
+`EXT_implicit_ellipsoid_region` extends the `shape` object in `KHR_implicit_shapes`. The `shape.type` should be set to `"ellipsoid region"`. The properties define the region following the surface of the ellipsoid between two different height values.
+
+The volume does not necessarily contain the full ellipsoid—and for many geospatial use cases, it will not. Rather, the ellipsoid is used as a reference from which the actual region is extruded. However, a region may be extend beneath the surface of the ellipsoid. Given the right height values, the region could contain the entire ellipsoid if desired.
+
+### Details
+
+The reference ellipsoid is centered at the origin. The `semiMajorAxisRadius` indicates the radius of the ellipsoid in meters along the `x` and `z` axes. The `semiMinorAxisRadius` indicates the radius of the ellipsoid in meters along the `y` axis.
+
+> The `x` and `z` radii are made equal to simplify the math required to render implicit regions along the ellipsoid.
+
+The `minHeight` and `maxHeight` properties indicate the heights of the region from the ellipsoid's surface in meters. A height of `0` sits right at the surface. Negative heights are also valid—they simply extend underneath the ellipsoid's surface.
+
+This example corresponds to the image below it:
+
+```json
+"extensions": [
+ {
+ "KHR_implicit_shapes": {
+ "shapes": [
+ {
+ "type": "ellipsoid region",
+ "extensions": {
+ "EXT_implicit_ellipsoid_region": {
+ "semiMajorAxisRadius": 3.5,
+ "semiMinorAxisRadius": 2,
+ "minHeight": 0,
+ "maxHeight": 0.5
+ }
+ }
+ }
+ ]
+ }
+ }
+]
+```
+
+
+
+An ellipsoid region may also be confined to a specific latitude and/or longitude range. The `minLatitude` and `maxLatitude` properties represent the latitude values at which the region starts and stops, defined in the range `[-pi/2, pi/2]`. Similarly, the `minLongitude` and `maxLongitude` properties represent the longitude bounds within the range `[-pi, pi]`.
+
+```json
+"extensions": [
+ {
+ "KHR_implicit_shapes": {
+ "shapes": [
+ {
+ "type": "ellipsoid region",
+ "extensions": {
+ "EXT_implicit_ellipsoid_region": {
+ "semiMajorAxisRadius": 3.5,
+ "semiMinorAxisRadius": 2,
+ "minHeight": 0,
+ "maxHeight": 0.5,
+ "minLongitude": 0,
+ "maxLongitude": 1.57079632679,
+ "minLatitude": -0.78539816339,
+ "maxLatitude": 0.78539816339,
+ }
+ }
+ }
+ ]
+ }
+ }
+]
+```
+
+
+
+It is valid for the `maxLongitude` property to be less than `minLongitude`. This would define a region that crosses over the line at `-pi` or `pi`, equivalent to the International Date Line on Earth.
+
+## Optional vs. Required
+This extension is required, meaning it should be placed in both the `extensionsUsed` list and `extensionsRequired` list.
diff --git a/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/half-ellipsoid.png b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/half-ellipsoid.png
new file mode 100644
index 0000000000..11f97c60be
Binary files /dev/null and b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/half-ellipsoid.png differ
diff --git a/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/hollow-ellipsoid.png b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/hollow-ellipsoid.png
new file mode 100644
index 0000000000..84abb5d206
Binary files /dev/null and b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/figures/hollow-ellipsoid.png differ
diff --git a/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_ellipsoid_region.schema.json b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_ellipsoid_region.schema.json
new file mode 100644
index 0000000000..70f023ccd5
--- /dev/null
+++ b/extensions/2.0/Vendor/EXT_implicit_ellipsoid_region/schema/glTF.KHR_implicit_shapes.shape.EXT_implicit_ellipsoid_region.schema.json
@@ -0,0 +1,66 @@
+{
+ "$schema": "https://json-schema.org/draft/2020-12/schema",
+ "$id": "glTF.KHR_implicit_shapes.shape.EXT_implicit_ellipsoid_region.schema.json",
+ "title": "EXT_implicit_ellipsoid_region extension on KHR_implicit_shapes.shape",
+ "type": "object",
+ "description": "Extension of `KHR_implicit_shapes.shape` to represent an implicit ellipsoid region in a glTF model.",
+ "allOf": [
+ {
+ "$ref": "glTFProperty.schema.json"
+ }
+ ],
+ "properties": {
+ "semiMajorAxisRadius": {
+ "type": "number",
+ "description": "The radius along the semi-major axis of the reference ellipsoid in meters. Corresponds to the radii along the X and Z axes.",
+ "minimum": 0
+ },
+ "semiMinorAxisRadius": {
+ "type": "number",
+ "description": "The radius along the semi-minor axis of the reference ellipsoid in meters. Corresponds to the radius along the Y-axis.",
+ "minimum": 0
+ },
+ "minHeight": {
+ "type": "number",
+ "description": "The minimum height of the region relative to the ellipsoid's surface, in meters. May be negative."
+ },
+ "maxHeight": {
+ "type": "number",
+ "description": "The maximum height of the region relative to the ellipsoid's surface, in meters. May be negative."
+ },
+ "minLatitude": {
+ "type": "number",
+ "description": "The minimum latitude (a.k.a. polar angle) of the region, in radians. Must be in the range [-pi/2, pi/2].",
+ "minimum": -1.57079632679,
+ "maximum": 1.57079632679,
+ "default": -1.57079632679
+ },
+ "maxLatitude": {
+ "type": "number",
+ "description": "The maximum latitude (a.k.a. polar angle) of the region, in radians. Must be in the range [-pi/2, pi/2].",
+ "minimum": -1.57079632679,
+ "maximum": 1.57079632679,
+ "default": 1.57079632679
+ },
+ "minLongitude": {
+ "type": "number",
+ "description": "The minimum longitude (a.k.a. azimuthal angle) of the region, in radians. Must be in the range [-pi, pi].",
+ "minimum": -3.14159265359,
+ "maximum": 3.14159265359,
+ "default": -3.14159265359
+ },
+ "maxLongitude": {
+ "type": "number",
+ "description": "The maximum longitude (a.k.a. azimuthal angle) of the region, in radians. Must be in the range [-pi, pi].",
+ "minimum": -3.14159265359,
+ "maximum": 3.14159265359,
+ "default": 3.14159265359
+ }
+ },
+ "required": [
+ "semiMajorAxisRadius",
+ "semiMinorAxisRadius",
+ "minHeight",
+ "maxHeight"
+ ]
+}
\ No newline at end of file
diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/README.md b/extensions/2.0/Vendor/EXT_primitive_voxels/README.md
index 051903406b..33676cf46c 100644
--- a/extensions/2.0/Vendor/EXT_primitive_voxels/README.md
+++ b/extensions/2.0/Vendor/EXT_primitive_voxels/README.md
@@ -5,41 +5,53 @@
## Contributors
+
+- Janine Liu, Cesium
- Daniel Krupka, Cesium
- Ian Lilley, Cesium
- Sean Lilley, Cesium
+- Jeshurun Hembd, Cesium
## Status
+
Draft
## Dependencies
-Written against the glTF 2.0 specification.
+
+Written against the glTF 2.0 specification. Depends on the [`KHR_implicit_shapes`](https://github.com/eoineoineoin/glTF/tree/refs/heads/collisionShapeMerge/extensions/2.0/Khronos/KHR_implicit_shapes) extension.
## Overview
-This extension allows primitives to use their attribute data to represent volumetric (voxel) data.
+This extension allows mesh primitives to represent volumetric (voxel) data via custom attributes. Primitives that use this extension must set their `mode` to the constant `0x7FFFFFFF` (`2147483647`) used to indicate voxels.
-```
+Typical mesh primitives make use of the `POSITION` attribute to store positional mesh data. However, `POSITION` is neither required nor used by `EXT_primitive_voxels`. Instead, this extension relies on the `KHR_implicit_shapes` extension to describe the shape of the voxel grid.
+
+```json
{
+ "extensions": {
+ "KHR_implicit_shapes": {
+ "shapes": [
+ {
+ "type": "box",
+ "box": {
+ "size": [2, 2, 2]
+ }
+ }
+ ]
+ }
+ },
"meshes": [
{
"primitives": [
{
"attributes": {
- "_TEMPERATURE": 1
+ "_TEMPERATURE": 0
},
- "mode": 2147483648,
+ "mode": 2147483647,
"extensions": {
"EXT_primitive_voxels": {
- "dimensions": [8, 8, 8],
- "bounds": {
- "min": [0.25, 0.5, 0.5],
- "max": [0.375, 0.625, 0.625]
- },
- "padding": {
- "before": [1, 1, 1],
- "after": [1, 1, 1]
- }
+ "shape": 0,
+ "dimensions": [8, 8, 8]
}
}
}
@@ -49,34 +61,197 @@ This extension allows primitives to use their attribute data to represent volume
}
```
-The extension adds three new primitive modes, corresponding to voxel grid geometries:
-- `0x80000000` (`2147483648`) - A Cartesian box. The grid is a Cartesian grid of equally-sized boxes.
-- `0x80000001` (`2147483649`) - A cylinder. The grid is a stack of concentric rings, evenly divided around the circumference.
-- `0x80000002` (`2147483650`) - An ellipsoid. The grid is a set of concentric ellipsoids, divided evenly in latitude and longitude.
+Though voxels are commonly associated with cubic geometry on a box-based grid, this extension also allows voxels to be based on other shapes, including cylinder-based regions specified by [`EXT_implicit_cylinder_region`](../EXT_implicit_cylinder_region/) and ellipsoid-based regions specified by [`EXT_implicit_ellipsoid_region`](../EXT_implicit_ellipsoid_region/). The supported shapes are visualized below.
-The lowest byte is reserved for future voxel modes: `0x80000000`-`0x800000FF`.
-
-|Box|Cylinder|Ellipsoid|
+|Box|Cylinder|Region|
| ------------- | ------------- | ------------- |
-||||
+||||
+
+Voxels exist inside a bounding volume that conforms to the shape of the grid. The `dimensions` property refers to the number of subdivisions _within_ this bounding volume. Each value of `dimensions` must be a positive integer.
+
+The relationship between `dimensions` and the grid geometry is explained below.
+
+### Box Grid
+
+A **box** grid is a Cartesian grid defined by `x`, `y`, and `z` axes with equally-sized boxes. The `dimensions` correspond to the subdivisions of the box along the `x`, `y`, and `z` axes respectively.
+
+Elements are laid out in memory where the `x` data is contiguous in strides along the `y` axis, and each group of `y` strides represents a `z` slice.
+
+
+A uniform box grid that is subdivided into two cells along each axis.
+
+
+A box grid that is non-uniformly scaled and also non-uniformly subdivided.
+
+### Cylinder Region Grid
+
+A **cylinder** region grid is subdivided along the radius, height, and angle ranges of the region. The `dimensions` correspond to the subdivisions of those ranges, respectively.
+
+
+
+The cylinder is aligned with the `y`-axis in the primitive's local space. Its height is subdivided along that local `y`-axis from bottom to top. Subdivisions along the radius are concentric, centered around the `y`-axis and extending outwards. Finally, the angular bounds subdivided clockwise around the circumference of the cylinder.
+
+Elements are laid out in memory where the radial data is contiguous in strides along the cylinder's height, as if stacked in a column. Each group of height strides represents an angular slice on the cylinder.
+
+
+A cylinder that is subdivided into two cells along each axis.
+
+
+A smaller cylinder region with radial and angular bounds that is non-uniformly subdivided.
+
+### Ellipsoid Region Grid
+
+An **ellipsoid** region grid is subdivided along the longitude, latitude, and height ranges of the region. The `dimensions` correspond to the subdivisions of those ranges, respectively.
+
+Elements are laid out in memory where the longitude data is contiguous in strides along the region's latitude. Each group of latitude strides represents a height slice on the region.
+
+
+An ellipsoid region that is subdivided into two cells along each axis.
+
+
+
+An ellipsoid region that is non-uniformly subdivided.
+
+
+A hollow ellipsoid region that covers the entire ellipsoid, subdivided into two cells along each axis.
+
+### Padding
+
+The `padding` property specifies how many rows of attribute data in each dimension come from neighboring grids. This is useful in situations where the primitive represents a single tile in a larger grid, and data from neighboring tiles is needed for non-local effects e.g. trilinear interpolation, blurring, or antialiasing.
+
+`padding.before` and `padding.after` specify the number of rows before and after the grid in each dimension, e.g. a `padding.before` of 1 and a `padding.after` of 2 in the `y` dimension mean that each series of values in a given `y`-slice is preceded by one value and followed by two.
+
+Padding data must be included with the rest of the voxel data. In other words, given `dimensions` of `[d1, d2, d3]`, `padding.before` of `[b1, b2, b3]`, and `padding.after` of `[a1, a2, a3]`, the voxel primitive's attributes must contain `(d1 + a1 + b1)*(d2 + a2 + b2)*(d3 + a3 + b3)` elements. In the following example, the attributes on this voxel primitive must supply `(8 + 1 + 1)*(8 + 1 + 1)*(8 + 1 + 1) = 100` elements.
+
+```json
+"extensions": {
+ "EXT_primitive_voxels": {
+ "shape": 0,
+ "dimensions": [8, 8, 8],
+ "padding": {
+ "before": [1, 1, 1],
+ "after": [1, 1, 1]
+ }
+ }
+}
+```
-These grids all define "unit" objects centered at the origin, contained in the bounding box between `(-1, -1, -1)` and `(1, 1, 1)`. Node transforms should be used to position, orient, and scale the voxel grid as needed. The `POSITION` attribute is _not_ required or used by this extension - all positioning is through node transforms.
+### No Data Values
-The `dimensions` property of the extension specifies the voxel grid dimensions:
-- x / y / z for boxes
-- radius / height / angle for cylinders
-- longitude / latitude / height for ellipsoids
+Voxel primitives may optionally specify a "No Data" value (or "sentinel value") for its attributes to indicate where property values do not exist. This "No Data" value may be provided for any type of attribute, but must be defined according to the type of its `accessor`. For `normalized` accessors, the `noData` value should be specified as the raw data value *before* normalization.
-Dimensions must be nonzero. Elements are laid out in memory first-axis-contiguous, e.g. for boxes, `x` data is contiguous (up to stride).
+The "No Data" values for attributes must be defined in the `noData` object. Any key in `noData` must match an existing key in the primitive's `attributes` object. However, not all `attributes` are required to provide a `noData` value.
-The `bounds` property describes which section of the primitive is mapped to the voxel grid. `bounds.min` and `bounds.max` specify a "rectangular" region of the voxel grid in the appropriate coordinate systems:
-- Boxes: a rectangular region of the box, between `(-1, -1, -1)` and `(1, 1, 1)`. **This is essentially a no-op - prefer using node transforms for boxes**.
-- Cylinders: a slice of the cylinder, between `(0, -1, -pi)` and `(1, 1, pi)`
-- Ellipsoids: a surface patch with height, between `(-pi, -pi/2, 0)` and `(pi, pi/2, 1)`
+For instance, if a voxel primitive references the following accessors...
-The `padding` property specifies how many rows of attribute data in each dimension come from neighboring grids. This is useful in situations where the primitive represents a single tile in a larger grid, and data from neighboring tiles is needed for non-local effects e.g. trilinear interpolation, blurring, antialiasing. `padding.before` and `padding.after` specify the number of rows before and after the grid in each dimension, e.g. a `padding.before` of 1 and a `padding.after` of 2 in the `y` dimension mean that each series of values in a given `y`-slice is preceded by one value and followed by two.
+```jsonc
+"accessors": [
+ {
+ "type": "SCALAR",
+ "componentType": 5122, // SHORT
+ "normalized": true
+ },
+ {
+ "type": "VEC3",
+ "componentType": 5126, // FLOAT
+ },
+ // ....
+]
+```
+
+...then it may define `noData` values for its corresponding attributes like so:
+
+```json
+"meshes": [
+ {
+ "primitives": [
+ {
+ "attributes": {
+ "_TEMPERATURE": 0,
+ "_DIRECTION": 1,
+ "_DATA_CONFIDENCE": 2
+ },
+ "mode": 2147483647,
+ "extensions": {
+ "EXT_primitive_voxels": {
+ "shape": 0,
+ "dimensions": [8, 8, 8],
+ "noData": {
+ "_TEMPERATURE": [-32768],
+ "_DIRECTION": [-999.99, -999.99, -999.99]
+ }
+ }
+ }
+ }
+ ]
+ }
+]
+```
+
+Note that `_DATA_CONFIDENCE` intentionally does not specify a `noData` value. The attribute is expected to contain a valid value for every voxel cell.
+
+### Metadata
+
+This extension may be paired with the `EXT_structural_metadata` extension to convey more semantic information about the voxel attributes.
+
+```json
+{
+ "extensions": {
+ "EXT_structural_metadata": {
+ "schema": {
+ "classes": {
+ "voxels": {
+ "properties": {
+ "temperature": {
+ "type": "SCALAR",
+ "componentType": "UINT32",
+ "normalized": true,
+ "offset": 32.0,
+ "scale": 1.8
+ }
+ }
+ }
+ }
+ },
+ "propertyAttributes": [
+ {
+ "class": "voxels",
+ "properties": {
+ "temperature":{
+ "attribute": "_TEMPERATURE"
+ }
+ }
+ }
+ ]
+ }
+ },
+ "meshes": [
+ {
+ "primitives": [
+ {
+ "attributes": {
+ "_TEMPERATURE": 0
+ },
+ "extensions": {
+ "EXT_primitive_voxels": {
+ "dimensions": [8, 8, 8],
+ "padding": {
+ "before": [1, 1, 1],
+ "after": [1, 1, 1]
+ }
+ },
+ "EXT_structural_metadata": {
+ "propertyAttributes": [0]
+ }
+ }
+ }
+ ]
+ }
+ ]
+}
+```
-The padding data must be supplied with the rest of the voxel data - this means if `dimensions` is `[d1, d2, d3]`, `padding.before` is `[b1, b2, b3]`, and `padding.after` is `[a1, a2, a3]`, the attribute must supply `(d1 + a1 + b1)*(d2 + a2 + b2)*(d3 + a3 + b3)` elements.
+`EXT_structural_metadata` may also specify a `noData` value for a property attribute property. If `EXT_primitive_voxels` contains an entry in `noData` for the same attribute, the values **SHOULD** match betwen the two extensions.
## Optional vs. Required
This extension is required, meaning it should be placed in both the `extensionsUsed` list and `extensionsRequired` list.
diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/figures/cylinder-subdivisions.png b/extensions/2.0/Vendor/EXT_primitive_voxels/figures/cylinder-subdivisions.png
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new file mode 100644
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diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/figures/whole-ellipsoid.png b/extensions/2.0/Vendor/EXT_primitive_voxels/figures/whole-ellipsoid.png
new file mode 100644
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diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/bounds.schema.json b/extensions/2.0/Vendor/EXT_primitive_voxels/schema/bounds.schema.json
deleted file mode 100644
index fbaefefe20..0000000000
--- a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/bounds.schema.json
+++ /dev/null
@@ -1,34 +0,0 @@
-{
- "$schema": "https://json-schema.org/draft/2020-12/schema",
- "$id": "bounds.schema.json",
- "title": "Bounds",
- "type": "object",
- "description": "The bounds property describes which section of the primitive is mapped to the voxel grid. bounds.min and bounds.max specify a rectangular region of the voxel grid in the appropriate coordinate system.",
- "allOf": [
- {
- "$ref": "glTFProperty.schema.json"
- }
- ],
- "properties": {
- "min": {
- "type": "array",
- "items": {
- "type": "number"
- },
- "minItems": 3,
- "maxItems": 3
- },
- "max": {
- "type": "array",
- "items": {
- "type": "number"
- },
- "minItems": 3,
- "maxItems": 3
- }
- },
- "required": [
- "min",
- "max"
- ]
-}
\ No newline at end of file
diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/mesh.primitive.EXT_primitive_voxels.schema.json b/extensions/2.0/Vendor/EXT_primitive_voxels/schema/mesh.primitive.EXT_primitive_voxels.schema.json
index 080052b2ed..6198a5684c 100644
--- a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/mesh.primitive.EXT_primitive_voxels.schema.json
+++ b/extensions/2.0/Vendor/EXT_primitive_voxels/schema/mesh.primitive.EXT_primitive_voxels.schema.json
@@ -3,16 +3,24 @@
"$id": "mesh.primitive.EXT_primitive_voxels.schema.json",
"title": "EXT_primitive_voxels glTF Mesh Primitive extension",
"type": "object",
- "description": "`EXT_primitive_voxels` extension for a primitive in a glTF model, to specify voxel grid geomtetry for volumetric data",
+ "description": "`EXT_primitive_voxels` extension for a primitive in a glTF model to indicate voxel-based volumetric data",
"allOf": [
{
"$ref": "glTFProperty.schema.json"
}
],
"properties": {
+ "shape": {
+ "allOf": [
+ {
+ "$ref": "glTFid.schema.json"
+ }
+ ],
+ "description": "The index of the shape in `KHR_implicit_shapes` that the voxel grid adheres to."
+ },
"dimensions": {
"type": "array",
- "description": "Dimensions of the voxel grid. x/y/z for a box, r/z/theta for a cylinder, lon/lat/height for an ellipsoid.",
+ "description": "Dimensions of the voxel grid. The values are interpreted with respect to the shape indicated by `KHR_implicit_shapes`.",
"items": {
"type": "integer",
"minimum": 1
@@ -20,15 +28,27 @@
"minItems": 3,
"maxItems": 3
},
- "bounds": {
- "$ref": "bounds.schema.json"
- },
"padding": {
+ "description": "The optional padding of the voxels.",
"$ref": "padding.schema.json"
+ },
+ "noData": {
+ "description": "A plain JSON object, where each key corresponds to an existing semantic in the primitive's `attributes`, and each value is the attribute's `noData` value. A `noData` value represents missing data — also known as a sentinel value — wherever it appears.",
+ "type": "object",
+ "minProperties": 1,
+ "additionalProperties": {
+ "type": "array",
+ "description": "The `noData` value for the corresponding attribute. Array elements **MUST** follow the accessor's `componentType`, and its length must align with the accessor's `type`.",
+ "items": {
+ "type": "number"
+ },
+ "minItems": 1,
+ "maxItems": 16
+ }
}
},
"required": [
- "dimension",
- "bounds"
+ "shape",
+ "dimensions"
]
}
\ No newline at end of file
diff --git a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/padding.schema.json b/extensions/2.0/Vendor/EXT_primitive_voxels/schema/padding.schema.json
index ad94b3ed0c..70b59e5d0b 100644
--- a/extensions/2.0/Vendor/EXT_primitive_voxels/schema/padding.schema.json
+++ b/extensions/2.0/Vendor/EXT_primitive_voxels/schema/padding.schema.json
@@ -3,7 +3,7 @@
"$id": "padding.schema.json",
"title": "Padding",
"type": "object",
- "description": "The padding property specifies how many rows of attribute data in each dimension come from neighboring grids.",
+ "description": "The padding around a voxel grid. Specifies how many rows of attribute data come from neighboring grids in each dimension.",
"allOf": [
{
"$ref": "glTFProperty.schema.json"