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Implementing Mix Modes on Plotters Disclosure Number: IPCOM000064293D
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18

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Ayres, MD Holden, IG [+details]


INTRODUCTION This article describes how overlapping shaded lines and areas drawn in the three different modes can be clipped to produce the desired output on a plotter. Graphics systems, for example, the IBM Graphical Display Data Manager, can have three modes of drawing: Overpaint, Mix and Underpaint. See Fig. 1. If a green area is overpainted onto a red area, the intersection of the two areas will be coloured green. If the green area had been underpainted, the intersection would be coloured red. In mix mode, the intersection of two coloured areas is coloured with the mixture of the two colours. It is considered unnecessary to clip lines to lines or areas to lines because the area of intersection is so small.