Subject: Pffffft...
Date: Fri, 27 May 1994 18:02:37 -0500 (CDT)
From: kirvan@SSESCO.com
Greetings -
Today on the "Ask Captain Video Show"...
- Ed Totman
>Here's a diagram of a cycle object I'm using to simulate a pistonand
>cylinder.
>...
>...Can you
>think of abetter way so that piston and cylinder are aligned automatically?
>I tried bones but it didn't realy work the way I wanted it to.
Bones isn't intended for doing things like this. Bones is more for doing
character animation with contiguous (as opposed to grouped) objects.
I have done something similar with constraints and states that works well,
but it does have some drawbacks (I'll get to those later).
Add an axis and move it to the edge of your work area - this will be a
parent axis for the group you are about to make. Add a primative disk.
Add another axis and put it on the periphery of the disk (this will be the
pivot point for the cylinder). Add a tube (piston), scale it down, and
move and rotate it to the right (posative X) side of the disk you already
added.
Now group these all together - parent axis to disk, disk to pivot axis,
pivot axis to piston.
Now you have to set up the constraints by freezing parts of this group.
Freeze the parent axis in X,Y,and Z world position and rotation. Freeze
the disk in X and Z world rotation (you can still rotate it around Y).
Freeze the piston in X,Y and Z world rotation and in Y and Z world
position (the piston can still move in X).
Now, turn on constraints. Switch to object mode, and rotate the disk around
Y - voila - you should get the piston moving properly. Now use states to
come up with tween positions (the transformation requester can be used to
get the rotation angle precise).
The group needs the parent axis because the parent object is automatically
frozen, and I don't think you can rotate it. Also, you will have to create
a lot of tweens, because the constraint info isn't used in animation, and
the piston will take short cuts between key frames.
- Lesk and Paul
>I want to rende a very simple particle animation. Using a sphere
>(which represents a pinata), I want o hvae the polygons "fall" off the
>sphere where they are, affected only by gravity. I'd also lie them to
>bounce a little. Here's what I'm thinking:
>
>Sphere object, size 50,50,50 set at coordinates 0,0,100
>
>Ground coordinate to be 0
>
>No wind or any other horiontal motion...strictly vertical (gravity).
>
>Object axis is at the bottom of the object. The elayed button in the
>particle requester is set.
I don't remember exactly how I did this, but here is some things that
come to mind:
- keep the explode distance small
- set the time to terminal velocities to something very small (0)
- crank up the gravity until the particles move fast enough
If this doesn't help, ask again and I'll try to find some more definative
numbers for you.
- Jeff Owens
>Is anyone besides me havng trouble with scaling objects in the stage
>editor? What has happened is that I have a scene I'e been working on
>for the past few days. Now whenever I load an object and scale it and
>then save changes, it doesn't save the scaling. It saves the fact that
>the object is tere, just not that it is scaled to a certain size.
The axis of the object has to be scaled for the stage editor to "take" the
changes. Do your scaling with "Loc" (local) turned on. This only happens
when you scale independantly in different axes.
- Tom Setzer
> ...[ bones - tablecloth / flag / curtain, etc] ...
You may not have enough faces in the areas between the big and small
subgroups.
I hate ascii pix, but here goes...
|-------b1------------|
|--s1--|
|-------b2------------|
|--s2--|
_____________________________________
| |
| |
| z z |
| | y | |
| | | | |
| | +-x | |
| | object axis | |
| | | |
| +y +y |
| |
| bone2 bone1 |
|_____________________________________|
Make the plane, like, 20x20 faces. You can move/rotate the bones anywhere
you want. Rotate bone1 around its Z axis, and the region of b1 that isn't
part of s1 gets changed into an S curve - region s1 stays flat. You may
want to make the s1/s2 groups only one face wide.
Hope this makes some sense.
- Jason K.
>i've been trying to scale the camera on its local y interactively
>without success. I ca interactively scale all 3 local axes but
>not just one or two axes.
>
>The only way I found aroun it is to use the transformation
>requester. But I really wish it worked interactively ike it used
>to work.
It still does. Turn on camera lines - select the camers - hit s - hit l -
then drag the mouse around - it scales.
Later - sorry so long again.
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