@chriswman said:

Thanx for the reply but sketchup crashes everytime I try to "play".

Does anyone else have a problem with that model crashing? It seems to work OK on my PC. To ChrisWMan: Is it just my model crashing or are you generally having a problem with SP crashing?

I have attached a new file with examples of joining hinges and sliders. In this one I have not directly connected the hinge to the slider in case that is what is causing your crashing problem. Let me know if this one works. The small white connecting blocks can be made invisible if required.

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IndirectJoints.skp

Hi angy,

I'm afraid 'sand' might be too much for most computers to handle, so I have attached a model with a load of bricks that can be offloaded instead. I hope your son finds it inspirational and it spurs him on to greater things. Perhaps he might like to have a go at animating the wheels?

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dump truck2b.skp

Yes, it is possible. Just group the hinge with the piston and then connect to the rest of the model. This works, but is not very rigid. (See the red group in the attached model file.) A better way is to put an intermediate block between the hinge and the piston, which gives a more rigid set up. (See the green group in the attached.) If the intermediate group spoils the visual look of the model it can be made invisible or made smaller. If making smaller, increase the density of the intermediate object to compensate and maintain the rigidity. For some applications you might actually prefer the more flexible result of the direct method.

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DirectJoints.skp

Just for fun I have added some rudimentary suspension and steering control to your wheel assembly. Hope you find it useful.

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FRONT WHEEL JOINT3.skp

Check out the attached file. I have scaled up the whole model except the physics joints by a factor of ten, made the white cylinders cylindrical rather than the default rectangular shape and made the wheel a sphere rather than convex hull. All the joints move freely now.

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FRONT WHEEL JOINT2.skp

Hi jemaxwell,

If you you could upload a file with what you have so far it would be lot easier for us to pinpoint the problem.

Offhand it may be the small dimensions you are working with. Try building a similar model with everything scaled up by a factor of ten and see if that helps. Do your objects seem to be dominated by the size of the joints?

Kev.

Hi Angy and son,

Well your son made a good attempt and got everything lined up properly. He was just fell foul of the less intuitive aspects of using SketchyPhysics. I have attached a simplified and fixed windmill (windmill3) and another file (windmill2) to act as a tutorial for your son to practice on.

First thing I should mention is that the everything seems to have been made into one big group. Everything in a group moves as one and nothing in a group moves independently of other parts of the group and this is the main reason the windmill does not work.

Using windmill2 as the tutorial:

1. Select the big block and the two hinges and make them a group.
2. Click on the "UI" button and with the big block selected, tick the "static" box.
3. Select the 3 parts of the handle and make them a group. (Handle assembly)
4. Select the 4 rectangular blades and 2 cylinders and make them a group. (Fan assembly)
5. Select the handle and the fan assemblies and make them one group. (this makes them move together so need for a connecting axle through the block)
6. Click on the "Joint Connector Tool" (next to the "UI" button) and click on the big block.
7. Now holding "ctrl" (on the right of the keyboard) and with the big block still selected, click on the two hinges.
8. Press the spacebar or select the arrow pointer tool and click on the handle or fan. In the UI it should say connected to hinge4102 and hinge2418 if everything has been done right. The model should now be ready to run.

Some general rules:

If connecting two objects with a joint, the joint should be grouped with one of the objects and connected (using the joint connector tool) with the other object.

Parts that move independently should not be grouped together.

Use as few joints as possible. The original had 6 when 1 or 2 is sufficient.

Always group joints last as they do not work if grouped in lower layers.

Do not superimpose solids or separate groups on each other so that they share the same space. For example in the original model there was an axle passing right through the main block. This will cause problems. If you must do this, set one of the objects such as the axle to "no-collision" and "ignore" in the UI.

Hope that helps. Good luck!

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windmill3.skp

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windmill2.skp

@unknownuser said:

Well here is a quick and crude solution, it just checks if all the named blocks are positioned beyond the border.

Once again some really impressive ruby coding from Mr.K! I like the use of two gyros and cylinders for the corner squares. It all works so well!

Thanks for sharing this with us. I has a look at your mini game and I see there is a LOT I can learn from you. Your Ruby programming skills and knowledge of SketchyPhysics inner workings is just awesome.

About the game itself, bumping into your future/past self going about its/your business is mind bending, even more so than the well known "Portal" games. Hopefully you are not doing any damage to the fabric of time and what about the grandfather paradox?

Mr.K beat me to it!

My version has a gyro too, but I have added a hidden layer with chamfered corners which makes it less likely that the corners will catch on each other. You can pretty much "slam dunk" the pieces into place, but to be honest it not much improvement on Mr.K's version which is pretty good already.

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slidergame_v03e.skp