29th January 2007, 01:04  #1 
Junior Member
Join Date: Dec 2006
Posts: 12

Dynamic Movement Mathematical Explanation
First off i wanna apologise if this post is at all noobish, but i did search the forums and saw nothing which really helped, and i do realise that this is one of the most commonly asked Q's, but i'm asking it from a different (probably even more difficult to answer) perspective, so try an bear with me. So my Q is : can anybody give a (semi) mathematical explanation of what A dynamic movement is doing? I kind of understand how to use them, the very basics anyway, but the reason i ask is i'm doing my uni project in AVS n need to give an explanation of what the APE's i'm using are doing? specifically why do you get ghosting when you divide cartesian coordinates by less than 0.5, and what form of interpolation is used? I kinda understand the concept of interpolation but don't really get how it's used with the DM  i've messed around with grid size values and don't get how they relate to the image on screen & my knowledge of interpolation.
Again sorry to ask an age old question, but i am asking more from a pure understanding point, as opposed to "how do i make this to make stuff look cool?" 
29th January 2007, 18:37  #2 
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AVS Programming guide by PAK9
Skip to chapter 3 Jesus loves you [yes, you] so much, he even died for you so that you will not need to die, but live forever 
30th January 2007, 00:21  #3 
Junior Member
Join Date: Dec 2006
Posts: 12

Interpolation & Grid Sizes?
Thanks for the Quick Reply WOTL, i've already had a read of Pak9's Guide (its pretty much been my bible for learning AVS) and tbh i think I get What a DM is doing well enough to explain it(well at least give an example n let folk who haven't used them think its simple lol), what I don't understand is the whole interpolation thing, which i need to give a decent explanation off. for example if i plot a square In a SSC from points along all the 0.5 & 0.5 points, then use A DM to zoom by doubling x and y values, I get no effect with a gird size of 2x2 or less, but anything more (or turning wrap on) gives me a square half the size as you'd expect. I can see how it might be something to do with those points lying on the grid intersections where the interpolation is sampling from, but ... i can't... quite.... get it! I do (think) i get what interpolation does, i've know about it in different contexts I just don't quite get how it works in DM's. Any clues?

20th March 2007, 11:32  #4 
Major Dude

if you double x&y (x=0.5+0.5,y=0.5+0.5) by doing x*x and y*y, you'll get x0.25+0.25 and y0.25+0.25 for your result. however, if you do x*2 and y*2 you'll get x1+1 and y1+1, which is kinda backwards if you don't think about it too much, because if x=2, then x*x=4, and x*2=4, which can turn into a logical fallacy (you can easily fall into the assumption that x=0.5 then x*x=1 because x*2=1)
however, if x=3, then x*x=9, and x*2=6. 1*1=1, and 1*0.5=0.5=1/2, and 0.5*0.5=0.25=0.5/2 I sure hope I haven't lost you... I process these things weirdly in my head 

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