An electronic data processing pipeline system and method for processing encoded control points representing graphical illustrations. The pipeline comprises a number of separate micro-programmed circuit cards, each of which are programmed to perform a specific processing operation.
A command is first sent to a matrix maker card defining a geometrical transformation to be performed on the graphical illustration. The matrix maker card, together with a matrix multiplier card, then calculates a transformation matrix representing the desired transformation.
Electronic representations of control data points are then transmitted to the pipeline for processing. These control points are 3D points comprising both the vertices which terminate linear edges of the illustration and the control points corresponding to curved edges of the illustration. Each of the points is encoded to indicate whether it represents a vertex or a control point for a curved edge. In addition, the various points are encoded to indicate whether the corresponding portion of the illustration is to be rendered as a solid figure or a line drawing.
The control points are then multiplied by the transformation matrix, computed previously, in a vector multiplier circuit card. Next, the control points are clipped to the planes of the viewing frustum by a number of clipper cards (one card for each clipping plane). The 3D control points are then mapped onto the 2D viewing window by a viewport card.
Once the control points have been processed as set forth above, the clipped control points are then exploded to generate a plurality of small line segments representing each of the curved edges of the illustration. A sufficient number of line segments are generated for each edge such that the edges of the illustration appear smooth to the viewer. Finally, the appropriate portions of the illustration are rendered as a line drawing, in accordance with the code attached to the various control points; and the processed data is then converted into a form which is appropriate for scan conversion.