Querying Geometry

Each object in your xeometry viewer has a geometry, which describes its shape.

A geometry consists of:

• a primitive type ("points", "lines", "line-loop", "line-strip", "triangles", "triangle-strip" or "triangle-fan"),
• an array of World-space vertex positions (Float32Array),
• an array of tangent-space vertex normal vectors (Float32Array), and
• an array of indices (Int16Array or Int32Array), which index the vertex arrays to form primitives¹.

Examples

Getting an object's geometry primitive type:

var primitive = viewer.getPrimitive("saw#43");
// Eg. "triangles"

Getting the World-space vertex positions of the geometry of the object:

var positions = viewer.getPositions("saw#43");
// Eg. [2,2,2,-2,2,2,-2,-2,2,2,-2,2,2,2,2,2,-2,2,2,-2,-2,2,2,-2,

            // v0-v1-v6-v1 top
            2, 2, 2,
            2, 2, -2,
            -2, 2, -2,
            -2, 2, 2,

            // v1-v6-v7-v2 left
            -2, 2, 2,
            -2, 2, -2,
            -2, -2, -2,
            -2, -2, 2,

            // v7-v4-v3-v2 bottom
            -2, -2, -2,
            2, -2, -2,
            2, -2, 2,
            -2, -2, 2,

            // v4-v7-v6-v1 back
            2, -2, -2,
            -2, -2, -2,
            -2, 2, -2,
            2, 2, -2]

Note that the value of these positions will change whenever we transform the object (see Transforming).

Getting the tangent-space vertex normal vectors of the geometry of the object:

var normals = viewer.getNormals("saw#43");

Get the indices of the geometry of the object:

var indices = viewer.getIndices("saw#43");

Get the World-space boundary of an object's geometry's vertex positions (see Querying Boundaries):

var aabb = viewer.getAABB("saw#43");

Note that the extents of this boundary will change whenever we transform the object (see Transforming).

¹. The primitive type indicates the layout of the indices array - see The OpenGL Wiki for more information. ↩