Old 29th January 2007, 01:04   #1
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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 co-ordinates 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?"
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Old 29th January 2007, 18:37   #2
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AVS Programming guide by PAK-9
Skip to chapter 3

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Old 30th January 2007, 00:21   #3
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Interpolation & Grid Sizes?

Thanks for the Quick Reply WOTL, i've already had a read of Pak-9'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?
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Old 20th March 2007, 11:32   #4
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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 x-0.25+0.25 and y-0.25+0.25 for your result. however, if you do x*2 and y*2 you'll get x-1+1 and y-1+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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