GeometryPipeline

Methods

staticGeometryPipeline.combine(instances) → Geometry

Combines geometry from several GeometryInstance objects into one geometry. This concatenates the attributes, concatenates and adjusts the indices, and creates a bounding sphere encompassing all instances.

If the instances do not have the same attributes, a subset of attributes common to all instances is used, and the others are ignored.

This is used by Primitive to efficiently render a large amount of static data.

Name	Type	Description
instances	Array.<GeometryInstance>	optional The array of GeometryInstance objects whose geometry will be combined.

Returns:

A single geometry created from the provided geometry instances.

Throws:

• DeveloperError : All instances must have the same modelMatrix.
• DeveloperError : All instance geometries must have an indices or not have one.
• DeveloperError : All instance geometries must have the same primitiveType.

Example:

for (var i = 0; i < instances.length; ++i) {
  Cesium.GeometryPipeline.transformToWorldCoordinates(instances[i]);
}
var geometry = Cesium.GeometryPipeline.combine(instances);

See:

• GeometryPipeline.transformToWorldCoordinates

Source: Core/GeometryPipeline.js, line 894

staticGeometryPipeline.computeBinormalAndTangent(geometry) → Geometry

Computes per-vertex binormals and tangents for a geometry containing TRIANGLES. The result is new binormal and tangent 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 binormal and tangent 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.computeBinormalAndTangent(geometry);

Source: Core/GeometryPipeline.js, line 1180

staticGeometryPipeline.computeNormal(geometry) → Geometry

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);

Source: Core/GeometryPipeline.js, line 1037

staticGeometryPipeline.createAttributeLocations(geometry) → Object

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:

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

Source: Core/GeometryPipeline.js, line 251

staticGeometryPipeline.createLineSegmentsForVectors(geometry, attributeName, length) → Geometry

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

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:

var geometry = Cesium.GeometryPipeline.createLineSegmentsForVectors(instance.geometry, 'binormal', 100000.0),

Source: Core/GeometryPipeline.js, line 183

staticGeometryPipeline.encodeAttribute(geometry, attributeName, attributeHighName, attributeLowName) → Geometry

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');

Source: Core/GeometryPipeline.js, line 675

staticGeometryPipeline.fitToUnsignedShortIndices(geometry) → Array.<Geometry>

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:

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

Source: Core/GeometryPipeline.js, line 486

staticGeometryPipeline.projectTo2D(geometry, attributeName, attributeName3D, attributeName2D, projection) → Geometry

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');

Source: Core/GeometryPipeline.js, line 591

staticGeometryPipeline.reorderForPostVertexCache(geometry, cacheCapacity) → Geometry

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

Source: Core/GeometryPipeline.js, line 407

staticGeometryPipeline.reorderForPreVertexCache(geometry) → Geometry

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

Source: Core/GeometryPipeline.js, line 319

staticGeometryPipeline.toWireframe(geometry) → Geometry

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);

Source: Core/GeometryPipeline.js, line 139

staticGeometryPipeline.transformToWorldCoordinates(instance) → GeometryInstance

Transforms a geometry instance to world coordinates. This is used as a prerequisite to batch together several instances with GeometryPipeline.combine. This changes the instance's modelMatrix to Matrix4.IDENTITY and transforms the following attributes if they are present: position, normal, binormal, and tangent.

Name	Type	Description
instance	GeometryInstance	The geometry instance to modify.

Returns:

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

Example:

for (var i = 0; i < instances.length; ++i) {
  Cesium.GeometryPipeline.transformToWorldCoordinates(instances[i]);
}
var geometry = Cesium.GeometryPipeline.combine(instances);

See:

• GeometryPipeline.combine

Source: Core/GeometryPipeline.js, line 774

staticGeometryPipeline.wrapLongitude(geometry) → Geometry

Splits the geometry's primitives, by introducing new vertices and indices,that intersect the International Date Line so that no primitives cross longitude -180/180 degrees. This is not required for 3D drawing, but is required for correcting drawing in 2D and Columbus view.

Name	Type	Description
geometry	Geometry	The geometry to modify.

Returns:

The modified geometry argument, with it's primitives split at the International Date Line.

Example:

geometry = Cesium.GeometryPipeline.wrapLongitude(geometry);

Source: Core/GeometryPipeline.js, line 1888