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barycentric coordinates for quads

Hi everyone, some of you know how fill a quads in 2D using barycentric
coordinates?At the present, I'm splitting the quads into 2 triangles,
but that way is inefficient because I have to iterate over the second
bounding box which repeats pixel that were filled previously (by
example, to fill the 2nd triangle I traversed the 1st triangle that
belongs at bounding box formed by 2nd triangle)
Thanks

esmitt
0
esmitt (5)
6/30/2010 10:50:18 PM
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Am 01.07.2010 00:50, schrieb esmitt:
> Hi everyone, some of you know how fill a quads in 2D using barycentric
> coordinates?

I think we all know that that's a bad idea, so don't worry about its 
implementation too much.

> At the present, I'm splitting the quads into 2 triangles,
> but that way is inefficient because I have to iterate over the second
> bounding box which repeats pixel that were filled previously (by
> example, to fill the 2nd triangle I traversed the 1st triangle that
> belongs at bounding box formed by 2nd triangle)

You appear completely confused about the terms you're using.  What makes 
you think that filling using barycentric coordinates would require a 
bounding box?

And while we're at it: what makes you think barycentrics are a useful 
tool for a polygon into pixels?  They have nothing to do with pixels!
0
HBBroeker (925)
6/30/2010 10:55:04 PM
Thanks for your answer.

On Jun 30, 6:55=A0pm, Hans-Bernhard Br=F6ker <HBBroe...@t-online.de>
wrote:
> Am 01.07.2010 00:50, schrieb esmitt:
>
> > Hi everyone, some of you know how fill a quads in 2D using barycentric
> > coordinates?
>
> I think we all know that that's a bad idea, so don't worry about its
> implementation too much.
I know that a scanline solution better but for now, I need to use
barycentric coordinates.
>
> > At the present, I'm splitting the quads into 2 triangles,
> > but that way is inefficient because I have to iterate over the second
> > bounding box which repeats pixel that were filled previously (by
> > example, to fill the 2nd triangle I traversed the 1st triangle that
> > belongs at bounding box formed by 2nd triangle)
>
> You appear completely confused about the terms you're using. =A0What make=
s
> you think that filling using barycentric coordinates would require a
> bounding box?
Well, when I talk about bounding box is just like a delimiter for my
splitted triangle and iterate over each pixels and decides if (x,y) is
inside..nothing else

>
> And while we're at it: what makes you think barycentrics are a useful
> tool for a polygon into pixels? =A0They have nothing to do with pixels!
I'm using it to make another algorithms


0
esmitt (5)
6/30/2010 11:51:01 PM
Am 01.07.2010 01:51, schrieb esmitt:
> On Jun 30, 6:55 pm, Hans-Bernhard Br�ker<HBBroe...@t-online.de>
> wrote:
>> Am 01.07.2010 00:50, schrieb esmitt:

> I know that a scanline solution better but for now, I need to use
> barycentric coordinates.

How did you arrive at the conclusion that you "need" them?  I have to 
ask again, because they make no sense whatsoever for the job at hand.

> Well, when I talk about bounding box is just like a delimiter for my
> splitted triangle and iterate over each pixels and decides if (x,y) is
> inside..nothing else

And what would be keeping you from iterating over the bounding box of 
the entire quad, and just evaluating

	if (pixel_inside_triangle1(x,y) || pixel_inside_triangle2(x,y))

> I'm using it to make another algorithms

Well, if you're going to loop over pixels in bounding boxes, that 
effectively _is_ a scanline algorithm anyway --- so what's keeping you 
from using a proper one?
0
HBBroeker (925)
7/1/2010 1:24:25 PM
Reply:

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