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GeometryPipeline

GeometryPipeline

Content pipeline functions for geometries.

See:
Source:

Methods

<static>

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.

Parameters:
Name Type Argument Description
instances Array <optional>
 The array of GeometryInstance objects whose geometry will be combined.
Throws:
  • DeveloperError : instances is required and must have length greater than zero.
  • 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.
Returns:
Geometry A single geometry created from the provided geometry instances.
Example
for (var i = 0; i < instances.length; ++i) {
  GeometryPipeline.transformToWorldCoordinates(instances[i]);
}
var geometry = GeometryPipeline.combine(instances);
See:

<static>

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.

Parameters:
Name Type Description
geometry Geometry The geometry to modify.
Throws:
Returns:
Geometry The modified geometry argument with the computed binormal and tangent attributes.
Example
GeometryPipeline.computeBinormalAndTangent(geometry);

<static>

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.

Parameters:
Name Type Description
geometry Geometry The geometry to modify.
Throws:
Returns:
Geometry The modified geometry argument with the computed normal attribute.
Example
GeometryPipeline.computeNormal(geometry);

<static>

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

Parameters:
Name Type Description
geometry Geometry The geometry, which is not modified, to create the object for.
Throws:
DeveloperError : geometry is required.
Returns:
Object An object with attribute name / index pairs.
Example
var attributeIndices = GeometryPipeline.createAttributeIndices(geometry);
// Example output
// {
//   'position' : 0,
//   'normal' : 1
// }
See:

<static>

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.

Parameters:
Name Type Argument Default Description
geometry Geometry The Geometry instance with the attribute.
attributeName String <optional>
 'normal' The name of the attribute.
length Number <optional>
 10000.0 The length of each line segment in meters. This can be negative to point the vector in the opposite direction.
Throws:
  • DeveloperError : geometry is required.
  • DeveloperError : geometry.attributes.position is required.
  • DeveloperError : geometry.attributes must have an attribute with the same name as the attributeName parameter.
Returns:
Geometry A new Geometry instance with line segments for the vector.
Example
var geometry = GeometryPipeline.createLineSegmentsForVectors(instance.geometry, 'binormal', 100000.0),

<static>

Encodes floating-point geometry attribute values as two separate attributes to improve rendering precision using the same encoding as EncodedCartesian3.

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

Parameters:
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.
Throws:
Returns:
Geometry The modified geometry argument, with its encoded attribute.
Example
geometry = GeometryPipeline.encodeAttribute(geometry, 'position3D', 'position3DHigh', 'position3DLow');
See:

<static>

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 Context#getElementIndexUint is false.

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

Parameters:
Name Type Description
geometry Geometry The geometry to be split into multiple geometries.
Throws:
  • DeveloperError : geometry is required.
  • 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.
Returns:
Array An array of geometries, each with indices that fit into unsigned shorts.
Example
var geometries = GeometryPipeline.fitToUnsignedShortIndices(geometry);

<static>

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.

Parameters:
Name Type Argument Default Description
geometry Geometry The geometry to modify.
projection Object <optional>
 new GeographicProjection() The projection to use.
Throws:
DeveloperError : geometry is required.
Returns:
Geometry The modified geometry argument with position3D and position2D attributes.
Example
geometry = GeometryPipeline.projectTo2D(geometry);

<static>

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.

Parameters:
Name Type Argument Default Description
geometry Geometry The geometry to modify.
cacheCapacity Number <optional>
 24 The number of vertices that can be held in the GPU's vertex cache.
Throws:
Returns:
Geometry The modified geometry argument, with its indices reordered for the post-vertex-shader cache.
Example
geometry = GeometryPipeline.reorderForPostVertexCache(geometry);
See:

<static>

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

Parameters:
Name Type Description
geometry Geometry The geometry to modify.
Throws:
  • DeveloperError : geometry is required.
  • DeveloperError : Each attribute array in geometry.attributes must have the same number of attributes.
Returns:
Geometry The modified geometry argument, with its attributes and indices reordered for the GPU's pre-vertex-shader cache.
Example
geometry = GeometryPipeline.reorderForPreVertexCache(geometry);
See:

<static>

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.

Parameters:
Name Type Description
geometry Geometry The geometry to modify.
Throws:
Returns:
Geometry The modified geometry argument, with its triangle indices converted to lines.
Example
geometry = GeometryPipeline.toWireframe(geometry);

<static>

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 {@see Matrix4.IDENTITY} and transforms the following attributes if they are present: position, normal, binormal, and tangent.

Parameters:
Name Type Description
instance GeometryInstance The geometry instance to modify.
Throws:
DeveloperError : instance is required.
Returns:
GeometryInstance The modified instance argument, with its attributes transforms to world coordinates.
Example
for (var i = 0; i < instances.length; ++i) {
  GeometryPipeline.transformToWorldCoordinates(instances[i]);
}
var geometry = GeometryPipeline.combine(instances);
See:

<static>

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.

Parameters:
Name Type Description
geometry Geometry The geometry to modify.
Throws:
DeveloperError : geometry is required.
Returns:
Geometry The modified geometry argument, with it's primitives split at the International Date Line.
Example
geometry = GeometryPipeline.wrapLongitude(geometry);
Documentation generated by JSDoc 3 on Tue Sep 03 2013 11:10:57 GMT-0400 (EDT)