i want a script to move objects smoothly

[sneakyimp webforumsuser@macromedia.com]

hey folks:

i've been doing some animation and one problem i have repeatedly is that i want to mimic REAL 3d movement....in particular, i want to move objects by the user as they would appear to move if the user was moving with some constant velocity and a 90 degree field of view (pi/2). this could be really cool as it might help a lot for creating realistic movement for 3d type space games or something.

i believe TRIGONOMETRY will be my salvation but my math skills are somewhat stunted these days.

if i assume the following:
1) some object on the screen with dimensions X and Y (in meters?) at distance D moving with velocity V (in a more general case, this would be a 3d velocity with X, Y, and Z components).
2) i have a 90 degree field of view

at one point, i did a simplified approximation of this problem...i assumed the object (a planet in this case) would be flying toward the viewer but the viewer was going to go some 10 meters to one side of the object.

anyways....has anyone done something like this? i've seen some animations which are obviously using formulas of some kind for motion as they are so smooth and realistic looking.

[Pea webforumsuser@macromedia.com]

Hi sneakyimp,

I'm afraid if your basic trig skills are waning, you will have major problems with "real" 3D. These require quite complex vector and matrix calculations, even without lighting and texturing....

Perhaps what you are trying to do, or imagine, is using flash's normal tools (rotation, tweening, resizing of clips etc) to create a clever illusion of 3d movement?

With planets its not so bad because these are spherical, and from any angle on a 2D surface (the screen) these will look the same - i.e. like a circle basically.

Your movement of a planet may go something like this:

1) Make a planet clip with a nice drawing/animation of a planet and place it on the stage.
2) Make it very small and near the center in frame 1
3) Make a keyframe in frame 30, and in this frame resize the planet to 300% and place it just off the side of the stage.
4) RIght click between the keyframes (e.g. frame 20) and select motion tween.

Hey presto. looks like 3D....

I have attached a clip of the first part of a movie I am making using only flash tools and a bit of scripting... you can do some cool stuff without doing "3D".

Hope it helps,
Pea

[url]http://webforums.macromedia.com/attachments/scene001a.zip[/url]

[sneakyimp webforumsuser@macromedia.com]

i know motion tweens....the problem is that a simple motion tween doesn't look realistic. the objects tend to scale much more quickly as an objects approaches the viewer....it's a logarithmic sort of thing...things very small when far grow quickly in size as they approach...

my statement that my math skills are not so great wasn't intended to suggest that i am incapable of implementing complex equations...i've been thru hardcore math in college...it was more go suggest that i don't want to recreate the equations from scratch...i've found this useful article but it has some flash 4 stuff that i'm trying to modernize (and apparently i'm encountering some problems with variable scope).

[url]http://www.flashkit.com/tutorials/3D/3D_Engin-KStor-189/index.php[/url]

[Pea webforumsuser@macromedia.com]

Hi,

Not questioning your math skills at all...
Here are a few tips that may help doing it the 'easy' way...

1) Add more keyframes to a motion tween to slow the object down at the appropriate times - or -
2) Use the 'ease in/ease out' features to slow the object at the appropriate times (this works really well)

Or doing it with script:

3) Instead of tweening, use a function to calculate the new scale based on whatever factors you want (e.g. log). Call the function giving it the distance from the viewer, and it gives you back the scale of the clip.

Cheers,
Pea

[sneakyimp webforumsuser@macromedia.com]

thanks pea...


i actually did one flash movie with planets whizzing past...i sat down and did about 3 pages of trig and it worked pretty well....i just manually scaled stuff according to calculations i put in a spreadsheet. (note: had to be careful of dividing by 0!).

i've been trying to think of ways to do that in a flash movie where i can just put in a formula but i wasn't sure where to put my formula...in the object that's scaling? in my main movie? i was also hoping that someone else out there had done this before and just had some good advice. admittedly, i'm being a bit lazy but thought it was worth a try.

as for the EAST IN/OUT stuff...i can't find any thing in the help file on that. where do i find it? what does it do? OH...just found it. hmmmm.....looks very interesting. THANKS! (fyi folks, EASE is found on the frame properties pane when you have selected a motion tween.