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Re: Circle?

Hi,


From: David Remahl <email@hidden>
Subject: Re: Circle?
To: email@hidden
Message-ID: <email@hidden>
Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes;
    format=flowed

Thanks for that suggestion! Hadn't thought of that...

I'm also replying to myself; I figured out how to act without source
material. The function I had missed in the reference material was
destCoord (). Here is some code generating a circle centered around
(0,0):

kernel vec4 circle ()
{
     vec4 v = destCoord ();
     float c = ( sqrt ( v.x*v.x + v.y*v.y ) < 300. ? 0. : 1. );
     return vec4 ( c, c, c, 1.0 );;
}

/ David 

A more efficient way to write this would be:

kernel vec4 circle(vec2 center, float radius, __color color)
{
return color * clamp(radius - distance(destCoord(), center), 0.0, 1.0);
}

the built-in function distance() is usually faster than using sqrt (sum of squares).
- Ralph

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