Geom
The Geom object collects together a GeomVertexData and one or
more GeomPrimitive objects, to make a single renderable piece of
geometry. In fact, an individual Geom is the smallest piece into which Panda
will subdivide the scene for rendering; in any given frame, either an entire
Geom is rendered, or none of it is.
Fundamentally, a Geom is very simple; it contains a pointer to a
single GeomVertexData, and a list of one or more GeomPrimitives, of various
types, as needed. All the associated GeomPrimitives index into the same
GeomVertexData.
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Geom
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The GeomVertexData pointer may be unique to each Geom, or one GeomVertexData may be shared among many different Geoms (each of which might use a different subset of its vertices). Also, although the GeomPrimitive objects are usually unique to each Geom, they may also be shared between different Geoms.
Although a Geom can have any number of GeomPrimitives associated with it, all
of the GeomPrimitives must be of the same fundamental primitive type:
triangles, lines, or points. A particular Geom might have GeomTriangles,
GeomTristrips, and GeomTrifans; or it might have GeomLines and GeomLinestrips;
or it might have GeomPoints. But no one Geom can have primitives from two
different fundamental types. You can call
geom.getPrimitiveType() to determine the
fundamental primitive type stored within a particular Geom.