Jump to content
  • Advertisement

Archived

This topic is now archived and is closed to further replies.

SuperTomate

Bezier interpolation, 3dsMax style

This topic is 5240 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hello all, I have a problem determining how 3dsMax 6.0 computes bezier interpolation. For a keyframe, max stores the key time, value, in tangent, out tangent, in length and out length. Up till the tangents, things are fine for me, but with the lengths I have no clue how the computation is done. All I know is that it influences velocity in some fashion. Does anyone know how 3dsMax works with beziers ? Thanks, SuperTomate

Share this post


Link to post
Share on other sites
Advertisement
Do you know how Bezier curve computation works in general? Typically, you're given 4 points. In this case, you can get the 4 necessary points from what they give you. You should already have the start and end points. Then, from the start point, you travel along the in tangent vector by the length given you. This is your second point. Your third is offset from the last point in the same way, but using the out tangent and the out length. So now you have x0, x1, x2, x3, y0, y1, y2, y3 (and z0, z1, z2, z3 if in 3D, which I suppose it would be... either way, it's all the same).

With those values, you can now get an equation for each dimension in the form

x(t) = ax·t3 + bx·t2 + cx·t + dx

where t goes from 0 to 1. And here is how you calculate the four constants:

dx = x0
cx = 3·(x1 - x0)
bx = 3·(x2 - x1) - cx
ax = x3 - x0 - bx - cx

Do this for the yn and zn values as well, and you have equations for calculating x, y, and z at time t.

[edited by - Agony on April 13, 2004 11:00:46 AM]

Share this post


Link to post
Share on other sites

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!