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Index › Programming Questions & Help › Syntax Questions › finding points between two vectors, help with alg
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finding points between two vectors, help with alg (Read 460 times)
oompa_l
finding points between two vectors, help with alg
May 1st, 2009, 9:09pm  
I'm having trouble with some simple math. I want to use a for loop to make equal vectors between two given vectors. I know that to get the midpoint you would add them together and divide by two but in order to get the quarter way point or the 3/4 way pt multiplying the summed pair by 1/4 and 3/4 (respectively) are not giving the right answers...I just need to develop a pattern so that I can cycle through a for loop and create the vectors as a function of the number of cycles...

I can't get my head around this one even though it's staring me in the face...help?
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Kaeltyk
Re: finding points between two vectors, help with alg
Reply #1 - May 2nd, 2009, 2:29am  
I think that's because you mutliply after summing.

You can do a loop like summing P1*a + P2*(1.0-a) (vector lerp) with a going from 0.0 to 1.0 and this will give you a point moving from P1 to P2.

your first case is (P1+P2)*0.5 = P1*0.5 + P2*(1.0-0.5), this is just the above equation with a = 0.5.

With your description I think what you're doing is (P1+P2)*a, and the result with a going from 0.0 to 1.0 is a point moving from 0 to (P1+P2).
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oompa_l
Re: finding points between two vectors, help with alg
Reply #2 - May 2nd, 2009, 8:59am  
Yes! it worked...I was trying to work backward as you did to figure out what the pattern in getting the (a+b)/2 but it just wasn't happening. Thanks for coming ot my rescue.
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