attributes
Attributes, which make up the geometry's vertices. Each property in this object corresponds to a GeometryAttribute containing the attribute's data.
Attributes are always stored non-interleaved in a Geometry.
There are reserved attribute names with well-known semantics. The following attributes are created by a Geometry (depending on the provided VertexFormat.
position- 3D vertex position. 64-bit floating-point (for precision). 3 components per attribute. See VertexFormat.position.normal- Normal (normalized), commonly used for lighting. 32-bit floating-point. 3 components per attribute. See VertexFormat.normal.st- 2D texture coordinate. 32-bit floating-point. 2 components per attribute. See VertexFormat.st.bitangent- Bitangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. See VertexFormat.bitangent.tangent- Tangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. See VertexFormat.tangent.
The following attribute names are generally not created by a Geometry, but are added to a Geometry by a Primitive or GeometryPipeline functions to prepare the geometry for rendering.
position3DHigh- High 32 bits for encoded 64-bit position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.position3DLow- Low 32 bits for encoded 64-bit position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.position2DHigh- High 32 bits for encoded 64-bit 2D (Columbus view) position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.position2DLow- Low 32 bits for encoded 64-bit 2D (Columbus view) position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.color- RGBA color (normalized) usually from GeometryInstance.color. 32-bit floating-point. 4 components per attribute.pickColor- RGBA color used for picking. 32-bit floating-point. 4 components per attribute.
geometry.attributes.position = new GeometryAttribute({
componentDatatype : ComponentDatatype.FLOAT,
componentsPerAttribute : 3,
values : new Float32Array(0)
});