SketchyPhysics Alpha

CPhillips · 5 Nov 2007, 11:28

i did that funny work
you need the last version of sketchyphysics http://code.google.com/p/sketchyphysics/wiki/LatestVersion

By the way. I see you made your track out of blocks. That is fine, but you can also just edit the floor. Any staticmesh (like the floor) can be edited at a per face level and will still work.

[url=http://www.sketchucation.com/forums/scf/sas/SketchyPhysics/avance3c-track.skp:33txugzx ]avance3c-track.skp[/url:33txugzx]

CPhillips · 5 Nov 2007, 11:29

@namza said:

@cphillips said:

@namza said:

i did that funny work
you need the last version of sketchyphysics http://code.google.com/p/sketchyphysics/wiki/LatestVersion

Very cool. That is the simplest self moving machine I have seen.

Chris

i made it afer a lost of test. The problem is that now i CAN'T ( !!) reproduce this machine. It goes with join and groups but all depends of what do i have to join ans what do i have to group ...and in wich order .....

You can use the joint connection tool to examine the way the joints are connected. In this case each of the 3 cylinders is grouped with a hinge. And the bars are just connected to the hinges.

Joint connections can be confusing at first.

not registered yet · 5 Nov 2007, 11:29

Chris,
That is nothing short of amazing. I'm awestruck. I'm curious as to why and what it took (in general terms) to create this.

Mark

P: marsol

CPhillips · 5 Nov 2007, 11:29

@unknownuser said:

Chris,
That is nothing short of amazing. I'm awestruck. I'm curious as to why and what it took (in general terms) to create this.

Mark

Thanks Mark.

The why is because its fun. I like making things that actually behave the way you'd expect.

What it took was a good physics engine (newton) and a lot of work. I have been working on it on and off for over 2 years. Its currently around 10k lines of ruby but I have probably written and discarded 20k.

Some of that 10k is code that isn't even enabled yet. SketchyReplay for example records animations and features some non-linear editing. Here is an example. Note the camera behavior and the rewind stuff at the end.

Chris

architectboy · 5 Nov 2007, 11:30

So, I've set up a Sketchy Physics competition for anyone who is interested in modeling with Sketchy Physics.

Krisidious · 5 Nov 2007, 11:30

is there or could there be, a way to turn on a shader, that would shade or highlight the area in which SketchyPhysics was available with in the model.

know what I mean? there is an area in which the Physics work and one where it does not, I'd like to see that area...

architectboy · 5 Nov 2007, 11:30

Yea, for some reason objects seem to stop moving about 200 feet from the origin.

Krisidious · 5 Nov 2007, 11:31

that's because the Physics are not global... it's just a small area around the axis...

not registered yet · 5 Nov 2007, 11:32

Very cool plug in!
If I move the sketchyphysics tool window any other toolbars that are open on my second monitor close.

P: SABBA

CPhillips · 5 Nov 2007, 11:32

You can adjust the size of the world under Plugins->Physics Settings. Adjust world scale to make it bigger or smaller. Note if you make it too big small things will stop working.

Chris

CPhillips · 5 Nov 2007, 11:32

@unknownuser said:

Very cool plug in!
If I move the sketchyphysics tool window any other toolbars that are open on my second monitor close.

Hm. Thats wierd. Ill look into it.

Chris

not registered yet · 5 Nov 2007, 11:33

@cphillips said:

Any other comments or feedback?

Has anyone used the SketchySolids toolbar? I am thinking that it is almost worthy of being a separate plugin.

Chris

Where can I download SketchySolids?

P: Invader ZIM

Krisidious · 5 Nov 2007, 11:33

is there a way to convert a regular group or component into sketchy solids?

CPhillips · 5 Nov 2007, 11:34

@unknownuser said:

is there a way to convert a regular group or component into sketchy solids?

Right click it and use the Set Shape menu.

CPhillips · 5 Nov 2007, 11:34

There are some pretty good user generated demos popping up on 3d warehouse. Here are a few good ones!
http://sketchup.google.com/3dwarehouse/details?mid=f27b91714ea5752a87d6d7c29947ae22
http://sketchup.google.com/3dwarehouse/details?mid=4ceb45eacc729c5ea611269c93d910
http://sketchup.google.com/3dwarehouse/details?mid=fefb0ae5c3399f426e49a9db8e76daf1
http://sketchup.google.com/3dwarehouse/details?mid=d972bcb8198c5770ac03d4486f1f7520

And a good YouTube video:
http://www.youtube.com/watch?v=YQquRx7rmkk

not registered yet · 5 Nov 2007, 11:34

Can I use a spring like a piece of elastic?

What I would like is that the model starts with the elastic stretched, so that once the simulation begins it will try to shrink to zero length (or some other predefined minimum length) pulling any attached object with it.

Where-as the spring seems not to exert any force on attached objects until it is either streched or compressed from the start position.

Ampa

CPhillips · 5 Nov 2007, 11:34

@ampa said:

Can I use a spring like a piece of elastic?

What I would like is that the model starts with the elastic stretched, so that once the simulation begins it will try to shrink to zero length (or some other predefined minimum length) pulling any attached object with it.

Where-as the spring seems not to exert any force on attached objects until it is either streched or compressed from the start position.

Ampa

It doesn't do that yet. Ill add it to my todo list.

Thanks Ampa.

not registered yet · 5 Nov 2007, 11:35

This is a great plugin - congrats of the work so far.

Noticed one other bug: pressing Ctrl+Z (Undo) while the simulation is running causes seriously bad things to happen! Can Undo be disabled temporarily?

Some more playing…

I decided to create a chain, and tried in a number of ways…

Create rings (torus) and arrange them so that they interlock in 3d space. Why does this not work? I assigned Shape:convexhull, but this is obviously not correct.
Create rectangular 'chain links' where each 'link' is made of 4 cuboids. This should overcome the convex hull issue and be easier on the maths Indeed it works! But looks ugly!
A different sort of chain… Created a linear array of cubes and inserted a ball joint between each one. At this stage I have a vertical column of swinging cubes, but they all act independently. And I can't work out how to correctly group the joints with the cubes to create a single chain of linked cubes. What is the correct way to do this?

P: Ampa

CPhillips · 5 Nov 2007, 11:35

@ampa said:

Noticed one other bug: pressing Ctrl+Z (Undo) while the simulation is running causes seriously bad things to happen! Can Undo be disabled temporarily?

Yeah, Ill mark it as a bug.

@ampa said:

Create rings (torus) and arrange them so that they interlock in 3d space. Why does this not work? I assigned Shape:convexhull, but this is obviously not correct.

A whole torus marked as convexhull will really resemble a solid wheel. If you want to create linked torus you need to break each segment of the torus apart into a convex hull and then group all the pieces. I did it once and it takes a while.

@ampa said:

A different sort of chain… Created a linear array of cubes and inserted a ball joint between each one. At this stage I have a vertical column of swinging cubes, but they all act independently. And I can't work out how to correctly group the joints with the cubes to create a single chain of linked cubes. What is the correct way to do this?

Group each of the ball joints with one of its two connected links and then use the JCT tool to connect the other link to the ball joint.

I should warn you that the ball joints aren't very stable when you connect them like this. The chain will fly wildly out of control if you try to move it too fast. This is a limitation of the underlying physics engine.

Chris

CPhillips · 5 Nov 2007, 11:36

"Google Guy" has an example.

Error 404 (Not Found)!!1

(sketchup.google.com)