Phun!- Free Physics simulator

Posted on May 18, 2008 at 5:01 am

No, I’ve not forgotten how you spell fun, Phun is, in fact a free Physics simulator. Despite its free nature, Phun’s Physics engine is eerily accurate, and even though it can be immensely useful to students who would like to really understand mechanics or dynamics a lot better, it was really designed with the intent of letting people design their own cool little machines and seeing how they would react in real-life situations.

Just to get you started off, I’ll be making a simple cart. But first things first, you need to download Phun. Its barely 2MB, so it shouldn’t take too long.

Once Phun is up and running, you should be looking at the home screen.

First off, some performance tweaks. If you have a slow system, un-tick the “Enable Shaders” and “Draw Clouds” options and tick the “Simple water rendering” box to make Phun lighter on resorces. Now we can get on with the designing!

Hold on! You should first familiarize yourself with your workspace:

The “Toolbar” on the left is pretty much all you need to design stuff. The “Control” Box helps you start and pause the simulation, as well as redo or undo something you did. The “Options” toolbar is used to fine tune performance and behavior.
If you click on “File”, you get several useful options such as loading one of the pre-designed scenes or even integrating them into your current scene.
Two of the most important tools in Phun are the “Brush” and “Drag” tools. The Brush tool is used to draw polygons, and only polygons. You cannot draw an open shape or even a line. If you just draw a line across something, it deletes that object. If while using the brush tool, you click and hold an object, you can even move it around the workspace.
The Drag tool helps you drag stuff around in real-time. What’s the difference between dragging and moving? Moving is merely relocating, while dragging actually simulates how the object would behave in real life. Dragging works only when the simulation is in progress.

Now, we can get to building that cart. You can create a lot of things in Phun, but they’ll all just hurtle into an abyss unless you have a plane to keep them on. So, select the Plane tool, and click and hold down somewhere near ground level. A plane should pop up, move your mouse until its level and release the mouse button. If done correctly, you will now have a plane!

As you can see, my plane is a nice green one.

Onward to the cart. Draw a Box and a Circle. Now right-click on the Circle and choose the Clone option. This is to ensure our wheels have the same size.

Once done, align them to form a cart. Like so:

Make sure the center of the wheels is higher than the base of the cart. Now, right-click on each wheel and choose the “Add center hinge” option from the “Geometry Settings”. If the hinge is too large, just erase it, Zoom in a bit, and try again. Now hit the Play button in the “Control” menu to see if your cart works!

If you did everything right, the cart should now fall to the ground [if it just stays there, make sure the "Gravity" check box is ticked] and bounce a bit. Choose the Drag tool and drag it around to see how it moves. You now have a fully functional cart!

You can always assign a hotkey to your cart by grouping it. To do so, draw a circle around it using the drag or brush tool and hit Ctrl+1 on your keyboard. Now you can select the cart as a whole by pressing the 1 key.

Remember, there are virtually endless possibilities in Phun. In this very scenario you could experiment with a slanting slope, or even a ramp built onto a slanting slope.

You could even read up a bit on some simple machines or load some of the pre-made scenarios for new ideas. Exploring Phun’s many features is sure to be a lot of fun, and don’t be scared to try stuff you don’t understand or know about, for you can always undo it!

This is a guest post written by Om J. Bathija, a tech enthusiast and blogger.

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