Primitive (geometry)

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In geometry, a primitive is the simplest of default geometrical figures or shapes. More complex figures are built up by combining primitives.

There is no rigorous, logical definition of a primitive. What counts as a primitive and what does not is largely a matter of personal opinion and convention, and varies depending on the context.

In Computer Science, a primitive can either be a point, a line or a polygon, although some people prefer to consider the triangle to be the two dimensional primitive, mostly because every polygon can be achieved with triangles. Primitives are used to create figures during runtime when to replace a sprite, or because this figure is not static (a meta-ball, for example). In three dimensions, triangles are used to render models. It is common word to say that a model which apparently lacks details (appears blocky or triangular) is low poly, or simply lacks polygons. Curves cannot be created with primitives, it is rather created by approximating the edge of the figure with a sufficient number of smaller lines, depending on the size of the surface.

Commonly used geometric primitives include:

• points
• lines and line segments
• planes
• circles and spheres
• triangles and other polygons