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From: robert@texas.asd.sgi.com (Robert Skinner)
Newsgroups: comp.graphics
Subject: Re: How to arbitarily break a bezier.
Message-ID: <1990Sep13.165916.21995@odin.corp.sgi.com>
Date: 13 Sep 90 16:59:16 GMT
References: <1990Sep12.235912.14229@allgfx.agi.oz> <776@sol.deakin.OZ.AU>
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In article <776@sol.deakin.OZ.AU>, peter@aragorn.cm.deakin.oz.au (Peter
Horan) writes:
|> See Foley Van Dam Feiner & Hughes which is open before me at the very
topic pp507-514
|> 
|> Given the control points P1, P2, P3, P4, a Bezier curve may be split
in half by computing L1 - L4 and R1 - R4
|> where
|> 	L1 = P1
|> 	L2 = (P1 + P2)/2
|> 	H  = (P2 + P3)/2
|> 	L3 = (L2 + H)/2
|> 	R2 = (H + R3)/2
|> 	L4 = R1 = (L3 + R2)/2
|> 	R3 = (P3 + P4)/2
|> 	R4 = P4
|> 
|> Draw a picture of it all. Its nice and easy.
|> -- 
|> Peter Horan

Or, if you want to split it into any a:1-a ratio, you can generalize 
the above interpolation equations:

	L2 = a*P1 + (1-a)*P2
	...

etc, etc.

So that splits the Bezier at an arbitrary point in *parameter* space.
Is that really what you wanted?  Or did you want to split it in object
space?

Robert Skinner
robert@sgi.com

	When I woke up this morning, my girlfriend asked if I had slept well.  
	I said, "no, I made a few mistakes."