bug: polygon
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Devil may Cry
Jan 3, 2013, 8:45:01 AM1/3/13
to haskel...@googlegroups.com
I believe I have stumbled upon another bug. This time in polygon function.
Try drawing this:
star = polygon [ -- line [ works fine
(0,50),
(10,30), -- bug or feature? it reads point, but shows it incorrectly
(40,20),
(20,0),
(30,-30),
(0,-10),
(-30,-30),
(-20,0),
(-40,20),
(-10,20)
-- (0,50)
]
It's easiest to spot if you add point by point:
translate 0 (-100) $ color red $ line my_star,
translate 0 (100) $ color blue $ polygon my_star
]
my_star = [
(0,50),
-- (10,30),
-- (40,20), -- line is ok, but polygon creates triangle surface, disregarding next points
--(20,0)
]
Try drawing this:
star = polygon [ -- line [ works fine
(0,50),
(10,30), -- bug or feature? it reads point, but shows it incorrectly
(40,20),
(20,0),
(30,-30),
(0,-10),
(-30,-30),
(-20,0),
(-40,20),
(-10,20)
-- (0,50)
]
It's easiest to spot if you add point by point:
translate 0 (-100) $ color red $ line my_star,
translate 0 (100) $ color blue $ polygon my_star
]
my_star = [
(0,50),
-- (10,30),
-- (40,20), -- line is ok, but polygon creates triangle surface, disregarding next points
--(20,0)
]
Chris Smith
Jan 3, 2013, 10:59:14 PM1/3/13
to haskel...@googlegroups.com
Gloss requires that your polygons are convex. If they are not, they often will not be drawn correctly.
--
Ben Lippmeier
Jan 3, 2013, 11:05:26 PM1/3/13
to haskel...@googlegroups.com, Chris Smith
On 04/01/2013, at 2:59 PM, Chris Smith wrote:
Gloss requires that your polygons are convex. If they are not, they often will not be drawn correctly.
Yeah, I just added this to the wiki. Someone needs to write a triangulation function.
It would be a GOOD holiday project...
Ben.
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