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Is this how keyframing works?

Started by AcidJazz Oct 28, 2002 at 10:10 AM 3 replies 1.3k views

Original Post

Oct 28, 2002 at 10:10 AM

Basically you store a certain number of frames for a certain animation then you go through them a fraction at a time? So for example if I had 100 vertices and 10 frames for lets say a person walking and 30 frames per second and it took 3 seconds to get through an entire walk cycle. I''d have to go 1/9th of the way for each x, y, z, between frame 1 & 2 right? However that''s a linear equation which has to cause some error, are there more accurate ways of doing this? Am I even thinking about this the proper way?

If you know any articles on key framing (or other methods of 3D animation) send em this way =) Thanks a lot

Waverider

108

Waverider

Oct 28, 2002 at 10:20 AM

Well, you may want to provide the ability to vary the amount of time between frames (that is, each frame has its own duration).

I had a character that used a run cycle with only 4 keyframes. the keyframes with the feet coming forward were long, and the step-down keyframes were fast, making it look more realistic.

simbobx

Oct 28, 2002 at 10:39 AM

You don''t have to use linear interpolation between frames .. you can use splines if you prefer (tho note that afaik splines need four control points not the two (start+end) which linear interpolation will use, so you''ll need a way to get/generate these. Not sure, but usually the previous & next frames in line are used).

Linear interpolation: use this frame + next frame
Spline : use last, this, next and next again.

nb: E&OE. I''ve never actually done this myself

Zorodius

Oct 29, 2002 at 10:24 AM

quote:
Originally posted by AcidJazz
Basically you store a certain number of frames for a certain animation then you go through them a fraction at a time?

Yep.

As far as I know, keyframing is normally done with linear interpolation and all frames considered to be the same amount of time apart. At least, that''s how I did it when I implemented a .MD2 viewer. Waverider''s suggestion would be a great way to save some space.

I don''t think using something besides linear interpolation would give a noticable improvement in the quality of the animation, but it would probably take a lot more processor time to do. Maybe it would be worth it if your frames were a long time apart, though.

Rian

Oct 29, 2002 at 10:31 AM

Because linear interpolenation is linear, vertices will only move in straight lines between keyframes. This is usually not a problem, though, because it happens too quickly for us to notice.

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