# GeometryPipeline

engine/Source/Core/GeometryPipeline.js 26
Content pipeline functions for geometries.

##### See:

- Geometry

### Methods

#### static Cesium.GeometryPipeline.compressVertices(geometry) → Geometry
engine/Source/Core/GeometryPipeline.js 1480

Compresses and packs geometry normal attribute values to save memory.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.

##### Returns:

The modified `geometry` argument, with its normals compressed and packed.

##### Example:

    geometry = Cesium.GeometryPipeline.compressVertices(geometry);

#### static Cesium.GeometryPipeline.computeNormal(geometry) → Geometry
engine/Source/Core/GeometryPipeline.js 1162

Computes per-vertex normals for a geometry containing `TRIANGLES` by averaging the normals of all triangles incident to the vertex. The result is a new `normal` attribute added to the geometry. This assumes a counter-clockwise winding order.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.

##### Returns:

The modified `geometry` argument with the computed `normal` attribute.

##### Throws:

- DeveloperError : geometry.indices length must be greater than 0 and be a multiple of 3.
- DeveloperError : geometry.primitiveType must be `PrimitiveType.TRIANGLES`.

##### Example:

    Cesium.GeometryPipeline.computeNormal(geometry);

#### static Cesium.GeometryPipeline.computeTangentAndBitangent(geometry) → Geometry
engine/Source/Core/GeometryPipeline.js 1333

Computes per-vertex tangents and bitangents for a geometry containing `TRIANGLES`. The result is new `tangent` and `bitangent` attributes added to the geometry. This assumes a counter-clockwise winding order.

Based on Computing Tangent Space Basis Vectors for an Arbitrary Mesh by Eric Lengyel.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.

##### Returns:

The modified `geometry` argument with the computed `tangent` and `bitangent` attributes.

##### Throws:

- DeveloperError : geometry.indices length must be greater than 0 and be a multiple of 3.
- DeveloperError : geometry.primitiveType must be `PrimitiveType.TRIANGLES`.

##### Example:

    Cesium.GeometryPipeline.computeTangentAndBiTangent(geometry);

#### static Cesium.GeometryPipeline.createAttributeLocations(geometry) → object
engine/Source/Core/GeometryPipeline.js 240

Creates an object that maps attribute names to unique locations (indices) for matching vertex attributes and shader programs.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry, which is not modified, to create the object for.

##### Returns:

An object with attribute name / index pairs.

##### Example:

    const attributeLocations = Cesium.GeometryPipeline.createAttributeLocations(geometry);
    // Example output
    // {
    //   'position' : 0,
    //   'normal' : 1
    // }

#### static Cesium.GeometryPipeline.createLineSegmentsForVectors(geometry, attributeName, length) → Geometry
engine/Source/Core/GeometryPipeline.js 166

Creates a new `Geometry` with `LINES` representing the provided attribute (`attributeName`) for the provided geometry. This is used to visualize vector attributes like normals, tangents, and bitangents.

Name | Type | Default | Description
--- | --- | --- | ---
`geometry` | Geometry |  | The `Geometry` instance with the attribute.
`attributeName` | string | `'normal'` | optional The name of the attribute.
`length` | number | `10000.0` | optional The length of each line segment in meters. This can be negative to point the vector in the opposite direction.

##### Returns:

A new `Geometry` instance with line segments for the vector.

##### Throws:

- DeveloperError : geometry.attributes must have an attribute with the same name as the attributeName parameter.

##### Example:

    const geometry = Cesium.GeometryPipeline.createLineSegmentsForVectors(instance.geometry, 'bitangent', 100000.0);

#### static Cesium.GeometryPipeline.encodeAttribute(geometry, attributeName, attributeHighName, attributeLowName) → Geometry
engine/Source/Core/GeometryPipeline.js 727

Encodes floating-point geometry attribute values as two separate attributes to improve rendering precision.

This is commonly used to create high-precision position vertex attributes.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.
`attributeName` | string | The name of the attribute.
`attributeHighName` | string | The name of the attribute for the encoded high bits.
`attributeLowName` | string | The name of the attribute for the encoded low bits.

##### Returns:

The modified `geometry` argument, with its encoded attribute.

##### Throws:

- DeveloperError : geometry must have attribute matching the attributeName argument.
- DeveloperError : The attribute componentDatatype must be ComponentDatatype.DOUBLE.

##### Example:

    geometry = Cesium.GeometryPipeline.encodeAttribute(geometry, 'position3D', 'position3DHigh', 'position3DLow');

#### static Cesium.GeometryPipeline.fitToUnsignedShortIndices(geometry) → Array.<Geometry>
engine/Source/Core/GeometryPipeline.js 495

Splits a geometry into multiple geometries, if necessary, to ensure that indices in the `indices` fit into unsigned shorts. This is used to meet the WebGL requirements when unsigned int indices are not supported.

If the geometry does not have any `indices`, this function has no effect.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to be split into multiple geometries.

##### Returns:

An array of geometries, each with indices that fit into unsigned shorts.

##### Throws:

- DeveloperError : geometry.primitiveType must equal to PrimitiveType.TRIANGLES, PrimitiveType.LINES, or PrimitiveType.POINTS
- DeveloperError : All geometry attribute lists must have the same number of attributes.

##### Example:

    const geometries = Cesium.GeometryPipeline.fitToUnsignedShortIndices(geometry);

#### static Cesium.GeometryPipeline.projectTo2D(geometry, attributeName, attributeName3D, attributeName2D, projection) → Geometry
engine/Source/Core/GeometryPipeline.js 616

Projects a geometry's 3D `position` attribute to 2D, replacing the `position` attribute with separate `position3D` and `position2D` attributes.

If the geometry does not have a `position`, this function has no effect.

Name | Type | Default | Description
--- | --- | --- | ---
`geometry` | Geometry |  | The geometry to modify.
`attributeName` | string |  | The name of the attribute.
`attributeName3D` | string |  | The name of the attribute in 3D.
`attributeName2D` | string |  | The name of the attribute in 2D.
`projection` | object | `new GeographicProjection()` | optional The projection to use.

##### Returns:

The modified `geometry` argument with `position3D` and `position2D` attributes.

##### Throws:

- DeveloperError : geometry must have attribute matching the attributeName argument.
- DeveloperError : The attribute componentDatatype must be ComponentDatatype.DOUBLE.
- DeveloperError : Could not project a point to 2D.

##### Example:

    geometry = Cesium.GeometryPipeline.projectTo2D(geometry, 'position', 'position3D', 'position2D');

#### static Cesium.GeometryPipeline.reorderForPostVertexCache(geometry, cacheCapacity) → Geometry
engine/Source/Core/GeometryPipeline.js 409

Reorders a geometry's `indices` to achieve better performance from the GPU's post vertex-shader cache by using the Tipsify algorithm. If the geometry `primitiveType` is not `TRIANGLES` or the geometry does not have an `indices`, this function has no effect.

Name | Type | Default | Description
--- | --- | --- | ---
`geometry` | Geometry |  | The geometry to modify.
`cacheCapacity` | number | `24` | optional The number of vertices that can be held in the GPU's vertex cache.

##### Returns:

The modified `geometry` argument, with its indices reordered for the post-vertex-shader cache.

##### Throws:

- DeveloperError : cacheCapacity must be greater than two.

##### Example:

    geometry = Cesium.GeometryPipeline.reorderForPostVertexCache(geometry);

##### See:

- GeometryPipeline.reorderForPreVertexCache
- Fast Triangle Reordering for Vertex Locality and Reduced Overdraw by Sander, Nehab, and Barczak

#### static Cesium.GeometryPipeline.reorderForPreVertexCache(geometry) → Geometry
engine/Source/Core/GeometryPipeline.js 315

Reorders a geometry's attributes and `indices` to achieve better performance from the GPU's pre-vertex-shader cache.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.

##### Returns:

The modified `geometry` argument, with its attributes and indices reordered for the GPU's pre-vertex-shader cache.

##### Throws:

- DeveloperError : Each attribute array in geometry.attributes must have the same number of attributes.

##### Example:

    geometry = Cesium.GeometryPipeline.reorderForPreVertexCache(geometry);

##### See:

- GeometryPipeline.reorderForPostVertexCache

#### static Cesium.GeometryPipeline.toWireframe(geometry) → Geometry
engine/Source/Core/GeometryPipeline.js 118

Converts a geometry's triangle indices to line indices. If the geometry has an `indices` and its `primitiveType` is `TRIANGLES`, `TRIANGLE_STRIP`, `TRIANGLE_FAN`, it is converted to `LINES`; otherwise, the geometry is not changed.

This is commonly used to create a wireframe geometry for visual debugging.

Name | Type | Description
--- | --- | ---
`geometry` | Geometry | The geometry to modify.

##### Returns:

The modified `geometry` argument, with its triangle indices converted to lines.

##### Throws:

- DeveloperError : geometry.primitiveType must be TRIANGLES, TRIANGLE_STRIP, or TRIANGLE_FAN.

##### Example:

    geometry = Cesium.GeometryPipeline.toWireframe(geometry);

#### static Cesium.GeometryPipeline.transformToWorldCoordinates(instance) → GeometryInstance
engine/Source/Core/GeometryPipeline.js 835

Transforms a geometry instance to world coordinates. This changes the instance's `modelMatrix` to `Matrix4.IDENTITY` and transforms the following attributes if they are present: `position`, `normal`, `tangent`, and `bitangent`.

Name | Type | Description
--- | --- | ---
`instance` | GeometryInstance | The geometry instance to modify.

##### Returns:

The modified `instance` argument, with its attributes transforms to world coordinates.

##### Example:

    Cesium.GeometryPipeline.transformToWorldCoordinates(instance);

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