[Ohrrpgce] SVN: teeemcee/12805 rasterizer: fix rounding errors which caused artifacts for almost-horizo

[subversion at HamsterRepublic.com]

teeemcee
2022-02-20 02:23:01 -0800 (Sun, 20 Feb 2022)
289
rasterizer: fix rounding errors which caused artifacts for almost-horizontal edges

The X intercept was miscomputed for such edges.

Removed the intermediate results LineSegment.m_{x,y}Intercept. Measure from one
end of the segment rather than from x=0 or y=0. m_slope has changed meaning.
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U   wip/rasterizer.cpp
U   wip/rasterizer.hpp