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  1. #7
    Administrator Redrobes's Avatar
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    I have a tut and talk about some of the common / basic image algorithms in the post:
    http://www.cartographersguild.com/sh...ings-explained

    also, arctan2 is a function in programming languages which implements arctan except that arctan would be required to be given values of infinity to get certain results from it so arctan2 function is coded to give explicit results for values where it would need to have given an infinity to get it. Arctan is usually used to get an angle from a gradient so when the value of dy -> 0 for dx/dy then the function returns PI/2 or -PI/2 as appropriate. It also handles the angles > +/- 90 deg properly. So arctan2 is a doddle to use else you need to write a few extra lines of code to trap the infinities if you use plain arctan.

    oh and arctan2 should give +/- pi not 2pi. From -pi to +pi is one full rotation.

    And if your after lots of formulas like the one you quoted for the random number gen then the wiki page of them is a good source:
    https://en.wikipedia.org/wiki/Linear...ence_generator
    Last edited by Redrobes; 04-13-2012 at 09:44 PM.

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