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Ehsan Kamrani
10-23-2005, 03:53 AM
Hi
I want to move an object in 3d space. The object should move on a curve with a constant velocity. My problem is that if i use from the following function:
R(t) = x(t) i + y(t) j + z(t) k = sin(t) i + j + 2*t k

Then the vector function is:

v(t) = d R(t) / dt = dx(t)/dt i + dy(t)/ dt j + dz(t) / dt k = cos(t) i + 0 j + 2 k

So | v | is:
sqrt( cos^2(t) + 0 + 4 ) = sqrt( 4 + cos^2(t) ).
As you see, | v | is not constant--it changes with time....

This is an example. There are many example that | v | is not a constant value. So what should i do?How the programmers solve such a problem?
Regards
-Ehsan-

jide
10-23-2005, 05:06 AM
Well I haven't looked at your equation, but you might find some that depends on the speed so that you can ensure it's always the same speed.

ToniS
10-25-2005, 05:56 AM
He Eshan,
my suggestion for this problem would be the following:
dt := time interval
t := total time intverals elapsed
v(dt) := movement per time invterval
now
pos(t+td) = pos(t) + v(dt)
This just came to my mind when I read your post, but i hope it helped you a little bit :)

Greetz
Toni