I use the excellent SpriteGrabber class from the corona forum to split the sheet.

Please use the current PhysicsEditor 1.0.6b2 or newer if you want to try this example – it might not work with 1.0.5.

While developing Lander Hero iPad Game, I had to deal with large number of physics bodies. In each level, I needed huge 2048x2048px cavern to work with the physics engine.

There were 50 levels and each level was divided to 20-25 smaller parts to keep the framerate smooth. So There was a need to convert over 1000 irregular cave parts into physical objects.

I started doing it manually, but soon realized the amount of work would be insane and started looking for third party tools to ease the work. I discovered Physics Editor which was exactly what I needed.

Using PhysicsEditor to trace the cavern parts

It was dead simple to use and traced complex physics bodies automatically. For its price, Physics Editor really is a bargain. I literally saved weeks in development time because of this wonderful software!

Lander Hero is a Corona SDK based game and available in App Store November 30th 2011.

http://www.physicseditor.de/?p=301 I had planned to release a bigger update with many wishes fulfilled but I had to pause on that and do a small release before since the big update is not in a stable phase yet.

Since I already used a preview version of PhysicsEditor for the book I had worked on together with Steffen Itterheim I now need to do a smaller release right now.

The book is called Learn cocos2d Game Development with iOS 5. It’s the update of Steffen’s old book with several add ons and also covering my both tools!

The blog post in german is here: PhysicsEditor in Verwendung mit Cocos2D

Thanks you, Christoph!

One important thing is that even simple shapes might get divided into several polygons – e.g. if one polygon is concave. In this case PhysicsEditor decomposes them into convex polygons and distributes mass according to the size of each polygon.

PhysicsEditor treats convex shapes as one shape. This means if you set parameters for a convex shape all concave sub shapes share the same values. The loader composes a body with all of them – so you don’t have to care about that.

Physics parameters

Shapes have physics parameters. They define how a body is moved by the physics engine.

Mass / density

Mass / density tells the physics engine how heavy an object is. This has effect on collisions between objects. It does not have any effect on how fast the bodies fall.

Friction

Friction comes in play when one object slides on another. Low friction lets the object slide a longer distance, higher values make the object stop faster.

Restitution / elasticity / bounce

Restitution, elasticity or bounce are used when objects collide. They get repelled depending on the strength of this value. E.g. a basket ball will usually have a high value here whereas a block of steal will have a low value.

Surface velocity (x,y) [chipmunk only]

This value can be used to create conveyor belts. The value creates a speed component on objects that collide / rest on the body.

Collision parameters

Additionally collision parameters can be set directly from PhysicsEditor.

Chipmunk

These are chipmunk’s physics settings:

Chipmunk collision settings

IsSensor

This value tells the physics engine that the shape is only used to create inform your main program about the collision but the shape itself does not collide with other objects.

Type

This is the collision type. Use this value to set up dedicated collision handlers using
cpSpaceAddCollisionHandler. The default exporter/importer for chipmunk added to PhysicsEditor uses int as cpCollisionType – the default for the chipmunk engine. You might want to change this by modifying the exporter.

Group

Shapes in the same non-zero group do not generate collisions. Useful when creating an object out of many shapes that you don’t want to self collide
The default exporter/importer for chipmunk uses int as cpCollisionGroup which is the default for chipmunk.

Layers

Shapes only collide if they are in the same bit-planes. i.e. (a->layers & b->layers) != 0 By default, a shape occupies all bit-planes.
You can set names for simpler reference in the left column under Bit’s name. To add a shape to a specific layer set the checkmark in the right column under Layers.

Starting from zero I found Emanuele Feronato’s Blog and took a quick lesson in Flash and Box2d. Starting with his tutorial I managed to get my own demo up and running, creating an exporter for PhysicsEditor. Surprisingly creating the exporter and demo while learning action script on the fly took only 3h(!).

The new exporter writes ActionScript source code which you can directly integrate into your Flash projects using the Box2D flash port.

How do you set up physics data right now?

It’s easy: Import the physics data with import and add a variable containing the class:

Next create the body with the createBody method:

Parameters are:

• Name of the body
• The world object
• Type of the body: static, dynamic, kinematic
• The user data to store into the body object

Download the demo project (it’s also included in the newest version): Flash-Box2D.zip

(Sprites used in this example are from VectorJungle.com)

The loader is located in the loaders folder inside the dmg file. The class is called GCpShapeCache. For windows users: The folder with the loaders is inside the application’s folder after the installation.

First create your physics data, publish and add the resulting file to your resources.

Next create your sprite and attach the physics shape:

Here’s the current draft: