Distance field blending

Kali

Fractal Supremo

Posts: 1138

Distance field blending

« on: November 15, 2012, 07:09:15 PM »

I want to achieve a blending effect between two distance-estimated objects.
I tried to do it my own way but no good results... Quilez describes a way to do it here: http://www.iquilezles.org/www/articles/distfunctions/distfunctions.htm
But he uses "smoothcurve()" function? What is it? at first I thought it was a GLSL function but is not, and I couldn't find any clear references about what this function means and what it does... huh?

Any clues?


« Last Edit: November 15, 2012, 07:32:47 PM by Kali »	Logged

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eiffie

Guest

Re: Distance field blending

« Reply #1 on: November 15, 2012, 07:25:09 PM »

I remembered another thread on this...
http://www.fractalforums.com/programming/overlapping-spheres/

THIS ANSWER CAME FROM SUBBLUE SO IT CARRIES SOME WEIGHT

I'm guessing smoothcurve is like the smoothstep function in OpenGL, which (from the spec):

Returns 0.0 if x <= edge0 and 1.0 if x >= edge1 and performs smooth Hermite interpolation between 0 and 1 when edge0 < x < edge1. This is useful in cases where you would want a threshold function with a smooth transition.
This is equivalent to:
t = clamp ((x – edge0) / (edge1 – edge0), 0, 1);
return t * t * (3 – 2 * t);

...or it may be like the exponential step function he shows here:
http://iquilezles.org/www/articles/functions/functions.htm


« Last Edit: November 15, 2012, 07:35:28 PM by eiffie »	Logged

Kali

Fractal Supremo

Posts: 1138

Re: Distance field blending

« Reply #2 on: November 15, 2012, 08:17:56 PM »

Thanks eiffie! The weird thing is that before opening this thread, I did a search here at the forums for the word "smoothcurve" and no results, I did it again now and I found the post you pointed at huh?


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