Forum: Poser - OFFICIAL

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<h1>Forum: Poser - OFFICIAL</h1>

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<h1>Subject: Loop-making script</h1>

<p><strong><a href="https://api.renderosity.com/users/Cage">Cage</a></strong> opened this issue on Apr 03, 2010 · 610 posts</p>

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            <a href="https://api.renderosity.com/users/markschum"><img class="rr-forum-print-avatar" src="https://rr-live-site.s3.amazonaws.com/static/default-avatar.png" /></a>
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<p>
    <strong>markschum</strong><span class="text-muted"> posted Mon, 19 April 2010 at 1:13 AM</span>

    
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            <p>This was on page 5 of this thread - repeated for convenience.</p>
<p>I found some good explanations on the internet for solving the formula for a parabola if you have 3 points on it.  so if you have (-4,4)(0,1) (3,2) as points you can get the values for y = ax^2 + bx + c  (general formula for a parabola)  values a.b.c  and then calculate<br />
for x = -4 to 3 step 0.5<br />
  y = etc<br />
next x   and create the curve.  (a bit more complex to calculate he exact positions and angles of each link but can be done ) </p>
<p>to solve you get three equations (one for each point known)  which can be solved by an inverse matrix multiplication <img src="../../mod/forumpro//art/emoticons/scared.gif" alt="" /><br />
which some kind mathematician did http://stackoverflow.com/questions/717762/how-to-calculate-the-vertex-of-a-parabola-given-three-points</p>
<p>here is the matrix thing expanded :</p>
<pre><code>&lt;pre class=&quot;prettyprint&quot;&gt;
&lt;span class=&quot;pln&quot;&gt;denom &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;=&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x2&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;&lt;br&gt;&lt;/br&gt;A &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;=&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y1&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y2&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;))&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;/&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; denom&lt;br&gt;&lt;/br&gt;B &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;=&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;^&lt;/span&gt;&lt;span class=&quot;lit&quot;&gt;2&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y2&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x2&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;^&lt;/span&gt;&lt;span class=&quot;lit&quot;&gt;2&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y1&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x1&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;^&lt;/span&gt;&lt;span class=&quot;lit&quot;&gt;2&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;y2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;))&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;/&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; denom&lt;br&gt;&lt;/br&gt;C &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;=&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x3 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x1&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;+&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x2 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;(&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt;x1 &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;-&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; x2&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;*&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; y3&lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;)&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; &lt;/span&gt;&lt;span class=&quot;pun&quot;&gt;/&lt;/span&gt;&lt;span class=&quot;pln&quot;&gt; denom    once you have the three values you can calculate any point on the curve  for x from x1 to x3 (the start and end positions)    This has point of reference issues and works for the parabola in a plane x,y    in a 3d situation you would find the plane of the endpoints, and rotate it parrallel to an axis.   Then when you calculate the curve and pose the chain, you have a simple rotation back into position.     I hope you can follow that :(     &lt;br&gt;&lt;/br&gt;&lt;/span&gt;
</code></pre>

        
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