Talk:Physics (activity)

Current work

• DONE Project hosting application being processed
• DONE User:Bjordan/Physics.activity/Slimming down Elements into its bare essentials for (1) Use (Box2D, python/activity scripts) and (2) Devel, (Box2d sources, building)
• Physics.activity/Activity+Menus

-Bjordan 19:25, 27 June 2008 (UTC)

From main page

Some discussion is required here... most shapes can't be defined simply by a single line. Any shape with fixed (relative) dimensions can, but that's not always what you want —Preceding unsigned comment added by [[User:{{{1}}}|{{{1}}}]] ([[User talk:{{{1}}}|talk]] • [[Special:Contributions/{{{1}}}|contribs]])

Teaching electricity in India

See this report recently posted to OLPC_India by User:Hbonwit. Cjl 16:30, 12 July 2008 (UTC)

Cjl -- this is great, thanks! Is there a central source for these sorts of in-the-field teaching-with-XOs documents? I added this to Physics. --Bjordan 21:17, 19 July 2008 (UTC)

Questions/Comments

I'm using the most recent (as of 16 July 2008) version from the git repository on joyride 2153

• The background is black, so I can't see the joint line very well (or not at all).
• The "pushpins" used to suspend an rectangular object flicker when an object joined to the rectangle is in motion. (not really a problem, but I just wonder why they do that).
• Is there any way to duplicate an object? (so that I can be sure that the "mass" of 2 objects is identical)
• Is there a way to change the color of an object once created (or choose the color before creation)?
• trying to use the joystick tool causes the program to crash.

--AuntiMame17 July 2008 2:11 UTC

A few things I plan to do should address most of these problems...

• A "world" tab will allow you to edit the color of the background or make it an image, in addition to changing the gravity vector (supported in Box2D). The black background is just leftover from when I was doing
  • Some speed tests of SDL drawing over image backgrounds are in order.
• The pushpin flicker is a problem User:Alexlevenson and I are looking in to -- we think it has something to do with the conversion from Box2D units (meters) to real units (pixels).
• Get the XML scene format together and allow groups of objects to be selected, moved together, duplicated and deleted much like shapes in a vector graphics editor
• Add a second-layer contextual menu much like Paint has to allow for changing of things like friction, restitution (bounce), color, etc
• Add the joystick tool (disabling it from showing for now). The joystick tool will allow you to click on an object and use the game buttons / arrow keys to move it around in various ways.
  • This is a first step towards letting kids make their own goal-based games from within Physics (or maybe move this to a new game building activity)
• Put all of these things in as bugs on Trac to keep track of issues

I always appreciate your helpful input, AuntiMame! :) Keep it up!

--Bjordan 16:05, 18 July 2008 (UTC)

Spent some time experimenting while on airplane. :)

Great program, many people around me on the airplane were very intrigued by the program.

Here's some ideas/thoughts while I was experimenting with various tools.

1. 'Environment' options : (Tool for 'settings' ?)
   1. Adjust 'time' from "off" to 'very fast' (so a scene can be created/setup, or accelerated )
   2. Adjust 'gravity' from "None" ("outer space"), to "very heavy" ("standing on Saturn")
      1. (or direction?) To center, to upper/lower Left/Right corner/edge ..
   3. Adjust default "bounce/resistance/friction", when two heavy object hit, do they 'stick' or 'slide'.
   4. Border (top and sides) interaction (hard edge, limitless, object size, etc)....
   5. Deform on interaction. (When two object hit, do they deform slightly and rebound, or solid?)
2. New Tools
   1. "Elastic" connections (string, rubber, bounce or rebound between to points)
   2. "Magnetism" attraction/repel of two objects (image two 'objects' fend off each other.)
   3. "Duplication" assign/record/macro to keys (? 1,2,3,4, etc ?) to make duplication of same object easier (i.e. circles of same size : hit key, click for new center)
   4. "Zoom" to zoom in or out of scene, for creation of large interactive scenes
   5. "EXPORT/IMPORT" of scenes, or starting points for demos (similar to v.01 demos, drop-down-box?)
   6. "Change Properties" of specific selected objects.
      1. Color, Resistance, Mass, texture-effect, solid/hollow, breakable, bounce, etc
3. Keyboard shortcuts for tools, time (faster/slower/off), gravity (off/lighter/heavier)
   1. (I thought I read somewhere there were, but I couldn't find them again)

:) Well, ok..  more than just one or two... ideas there..

If I have some time, I'll peek at the code and see if I can offer some patches... :)

--ixo 08:26, 6 August 2008 (UTC)

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