R

rasterize

To convert a projected point, line, or polygon, or the pixels of a bitmap or image, to fragments, each corresponding to a pixel in the frame buffer. Note that all primitives are rasterized, not just points, lines, and polygons.

rectangle

A quadrilateral whose alternate edges are parallel to each other in object coordinates. Polygons specified with glRect*( ) are always rectangles; other quadrilaterals might be rectangles.

rendering

Conversion of primitives specified in object coordinates to an image in the frame buffer. Rendering is the primary operation of OpenGL.

RGBA

The red, green, blue, and alpha color components of the RGBA mode.

RGBA mode

An OpenGL context in which its color buffers store red, green, blue, and alpha color components, rather than color indexes.