Algodoo

Nice job! I especially like that throttle gauge that sits in the sky a few meters above the ground!

I know exactly what you mean about the shaky objects, and there can be many reasons that cause it. One is if two objects that share the same collision layer are touching or overlapping each other. Another is when an object's mass is too small when it interacts with another object. Sometimes it requires a combination of changes to get a shaky object to stop shaking. Sometimes it's simply a matter of increasing the sim.frequency. The default value is 60Hz, and increasing it to 100Hz or a little higher will often smooth out a shaky scene. Try those things when you encounter shaky objects and see if they help.

Thanks Xray. and yeah I kinda got lazy with hiding the throttle

I don't think I explained the "shaky" problem right. its not the problem you're describing. It only happens when the scene is paused. When you zoom in and out everything slightly shifts back and forth, and gets moved more and more out of place over time. it can completely destroy mechanisms with tight tolerances like the engine and transmission.

Here's a scene I made a looong time ago that shows exactly what Im talking about.
open the scene and pause it and simple scroll in and out. you'll see what I mean.
http://www.algodoo.com/algobox/details.php?id=30140

Wow, that is very strange! I've never seen that happen before. I will look into what's causing it and get back to you. I'm sure that kilinich or electronicboy knows what causes it.

By the way, the shaking also happens when the scene is running.

Could you simplify controls like use arrows and auto-clutch.

The reason your dragster scene shakes is because the camera x position is 72000. If the dragster is moved closer to position [0,0], then the shaking will stop.

Nice job on this scene. The scene works well and I don't see any problem with it.

I'm pretty sure the shaking is because of the floating point percison and the farther from the origin point you get the less accurate Algodoo gets

The shake happened to me when an object goes really fast. Maybe it's what s_noonan said, but i'm not sure

10/10 That engine is pretty good, although you can make it even better if you change the spring's lenght instead of constant, from 0 to 10 for example. That will make it unrealistic because you'll have a 1 stroke engine, but who cares
Also check out the console, there's a "rand.normal" that gives errors. If you can, clean up that script!

s_noonan -- Thanks for figuring out that shaking problem!

But my rally car is really close to the center. It was shaking almost as bad as that dragster. And it seems to happen every time I make a somewhat complicated scene that isn't stationary. It happened with my tank, and it happened to my RX7.
But what's weird is only certain geoms shake, and it's usually ones that are glued together or glued to the background rather than using the fixate tool. If I delete the parts that are shaking it usually goes away for the whole scene.

Regarding:
"But my rally car is really close to the center. It was shaking almost as bad as that dragster."
1. Was it shaking when the scene was stopped?
2. What did you do to fix it?
Regarding:
"it's usually ones that are glued together"
If this happens only when the scene is running, then most likely some overlapping geometries have the same collision layer and are not glued together. Even if they were glued together at one time, gluing additional objects and ungluing subsets of objects may have unpredictable results. A test for overlapping colliding geometries is to save your scene and then take everything in the scene and uncheck all collision layers. If things stop shaking, then you know what (but not where) the problem is.
If the shaking objects are part of an engine or attached to a spring, then increasing sim.frequency may help.

Steve, make this experiment:
Take some objects, fix them together, and make them fly at a very high speed (like 1000 m/s or even more), then brake them with a spring for example, and zoom in on one of the fixjoints. That's what lethalsquirrel is trying to say I think.
The objects will move of place, and the fixjoint's borders will be irregular (same would happen with a hinge)

Yes The Linkage is right. It's just like. It's not because objects are colliding with eachother or anything like that. for example. if I take a box and glue a bunch of circles too it with "glue objects together" over time, the circles will begin to shift their position slightly. and you can see them vibrate back and forth ever so slightly when you zoom in and out. Sometimes if you were to select one of those circles and move it with the arrow keys while the scene was stopped, it would cause all the other circles to shift in the opposite direction. This is really hard to explain without experiencing it first hand.

Here's a screen shot of what Im talking about.
http://prntscr.com/3dqajr

Here is what it looked like before
http://prntscr.com/3dqata

The buckle and the treads all shifted position. This happened slowly over time as I worked on the scene.
All the geoms on that tire were glued together using "glue objects together" then I just used the fix tool to attach it to the body of the car.
Deleting that tire helped fix the problem.

The weird thing is. the car is in the center of the scene, and not going fast.

I don't know if this is what contributed to the shaking problem or not, but I recall someone in the Algodoo forum (maybe kilinich) said that you should never use both "glue together" AND fixates in the same geometries because unexpected things could happen. Either use only "glue" OR use fixates.

I thought I would mention this in case it has something to do with this issue.

Hm, try resetting algodoo. It does that to me, but very slightly

We may be looking at two different problems:
1. Camera shakes when too far away from origin.
Comment: The killer planes are 1000 meters from the origin. It appears that the Algodoo camera can't handle objects way beyond 1000 meters.
2. Objects glued together migrate relative to each other.
Comment: I don't know what causes this and can't seem to force it to happen. It appears that gluing together and using a fixate perform similar functions but use different methods. Maybe the methods conflict if you use a combination of fixate and gluing together. Normally in mechanical, electrical, and software systems you don't want two things determining the same output unless the components or functions match perfectly or have some compliance.

In regards to the belt and tire, if you just tighten up the belt a little, then all your problems will be solved.

The buckle moving is from floating point precision. Algodoo is trying to keep track of 1000's of different variables and to save ram and performance it isn't 100% accurate. Every time you undo your scene it shifts some items.

Thanks for the information guys. It makes a lot of sense now.

Another thing I just though of, is sometimes I accidentally drop objects with no collision group, so they just keep falling forever. I bet that has something to do with it too.

I did some tests and it appears that Algodoo does a good job tracking "glued together" and fixated objects and doesn't allow over-definition (two things determining the same output). I tried stretching the fixate mechanically and through code and can't seem to do it. It is interesting to note that both fixates and axles (fixJoint and hinges) are over-defined (both have geom0pos and geom1pos, but only need one of those to determine its world position). In the case of hinges, the hinge will stretch (compliance) if things don't add up right. In the case of fixJoints, the fixate will maintain its relative position with the top object if things don't add up right.

It appears that there is an opportunity for someone to create a "Migrating Object" scene that somehow demonstrates the problem. I would do it myself, but I don't know how to do it.

You can do that using scene.my.clone.pos or other variables. I've already done that, and if you fixate the clone and another object with a fixjoint (I haven't tested with glue) the fixjoint will appear in the center of a line between the two objects. Try it, it's pretty old.
See Kilinich's Super Portal Demo scene for details

Ok, I can get a fixjoint to appear between two separate objects, but the fixjoint looks crisp (not blurry) and the connected objects do not migrate, so I don't see the connection between this and the migrating object problem. I also don't see the connection between Kilinich's "Super Portal Demo" scene and scene.my.clone.pos, fixjoints, or migrating objects since none of those are in the scene.

I just wanted to say that if you attach two objects with a fixjoint, and then you modify one of the object's pos constantly (for example, using clone feature), the fixjoint will appear between the two objects. A similar effect can happen when the object is very far from the center point, at least in algodoo 2.0.2b15

OK. Thanks for making me aware of that.

So here's the best story I can come up with:

Every time you run and then undo a scene all the objects are spawned on the redo. For some reason the objects don't come back in the exact location and complicated shapes are worse at relocating than simple boxes or circles. Also the location error gets larger the further you are from the origin. I'm not sure if the story is true but its my best guess.

Good guess. Neither I know, but what should be interesting to see is if two objects are so moved tht the fixjoint is NOT overlapping any object, those two objects are still fixed together? They should. I can't test it because it doesn't happen for me