Farseer Games: Blog

Farseer Games Blog Has Moved To www.FarseerGames.com

Thu, 17 Jan 2008 19:50:32 GMT

My blog as moved to www.farseergames.com

My First Farseer Interview

Mon, 19 Nov 2007 18:55:29 GMT

The folks over at www.infoq.com interviewed me regarding the Farseer Physics Engine.

Read it here:

http://www.infoq.com/news/2007/11/Farseer

Farseer Physics Engine 1.0.0.1 Released

Tue, 30 Oct 2007 09:19:42 GMT

Get the details here:

https://www.codeplex.com/Release/ProjectReleases.aspx?ProjectName=FarseerPhysics&ReleaseId=8008

The Farseer Physics Engine has been rebooted!

Wed, 03 Oct 2007 09:47:35 GMT

Jump right to the download page

The Details

This version supports XNA on both Windows and XBOX 360
This version supports Silverlight 1.1. See demo here. (Thanks Bill Reiss)
For a complete list of features see the home page.
To get late breaking news read my blog.
For acknowledgments see the acknowledgments page.
See screenshots and videos.
If you have questions please use the discussion page.
It's FREE!

Enjoy!

Thursday It Is!

Mon, 01 Oct 2007 00:55:52 GMT

I've decided Thursday will be the day I release the new version of Farseer.

I will not have all the documentation complete, but I will have all the samples done so you can refer to the code for now to see how things should be done.

I'm also going to include a very simple stand-alone Quick Start sample so people can see what it takes to make something happen with Farseer without having the clutter of the samples framework to get in the way.

Till Thursday!

-Jeff

A New Logo

Mon, 24 Sep 2007 01:30:09 GMT

The Farseer Physics Engine has a new logo.

I'd like to thank Jeremy Bishop of Zampano Studios for facilitating the creation of this logo and Stefan Warias for creating it.

Here is the logo: (please let me know what you think)

The release is still on schedule for the 1st week in October. I'll be spending this week tying up any looses ends and starting the docs.

-Jeff

The 1st Week of October

Mon, 17 Sep 2007 01:40:38 GMT

For those waiting for the new release of the Farseer Physics Engine, you will only need to wait till the 1st week in October. I have decided that is the week I'll post the new engine to Codeplex.

I said quite a while ago that I would not release the next version of Farseer until I had documentation. Well, I decided not to wait for the docs. I'll have a start on the documentation and will release what I have, but it will not be complete.

I will be releasing a number of samples as part of the samples project that will come with the engine, so people should be able to figure the basics out be looking at those.

Finally, I have a small surprise that might interest some (Thanks Bill). You'll have to wait till the release date to find out what it is.

And for the last time, the task list:

~~Limited Angle Joint (Joint limits for the RevoluteJoint)~~

~~Pin Joint with softness (60% complete)~~

~~Slider Joint with softness~~

~~Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)~~

~~Rewrite/Cleanup Collide method~~

~~Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)~~

~~Breakable Joints and Springs~~

~~Queue-up Added and Removed items and remove them when it's safe to do so.~~

~~Joint API (just some general clean-up of the Joint objects)~~

~~User Data Object (Tag property)~~

~~Factory Objects~~

~~Make static classes~~
~~Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)~~
- ~~Method(x, y, z)~~
- ~~Method(simulator, x, y, z)~~

~~General code clean-up~~

Docs! (in progress)

New LOGO! (in progress, thanks Jeremy)

Website (bare-bones for now) (on hold till after release)

RELEASE!!!!!!!

Move on to my ultimate goal: Make some cool physics based games. (can't wait!)

Feature Complete!

Mon, 10 Sep 2007 01:48:06 GMT

A milestone of sorts. All new features for this release are done!

Here are a few of the things I finished up this week.

Breakable joints are done!

I've added a "Tag" property to both the Body and Geometry object. This is similar to ODE's "UserData" object. It's also similar to the Tag object hanging off Forms in .Net. It allows the user to attach any type of object they please. This could be helpful in conjunction with a collision callback. The simplest example I can think of would be to use the Tag object to hold a name/description of some sort.

All Add/Remove calls now queue up the request and actually do the adding and removal at the beginning of the Update().

Next in line is the cleanup/refactoring of the factory objects. (for the formal OO coders out there, the factory objects in Farseer are not true Factory patterns, the name just fit)

Here's the task list for those keeping score.

~~Limited Angle Joint (Joint limits for the RevoluteJoint)~~

~~Pin Joint with softness (60% complete)~~

~~Slider Joint with softness~~

~~Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)~~

~~Rewrite/Cleanup Collide method~~

~~Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)~~

~~Breakable Joints and Springs~~

~~Queue-up Added and Removed items and remove them when it's safe to do so.~~

~~Joint API (just some general clean-up of the Joint objects)~~

~~User Data Object (Tag property)~~

Factory Objects

Make static classes
Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)
- Method(x, y, z)
- Method(simulator, x, y, z)

General code clean-up

Docs!

New LOGO!

Website (bare-bones for now)

RELEASE!!!!!!!

Move on to my ultimate goal: Make some cool physics based games.

Progress Report + Video Preview.

Tue, 04 Sep 2007 01:29:20 GMT

I made some good progress on breakable joints this week.

All joints and springs will have a Breakpoint and a JointError (or SpringError) value. The JointError is a measure of how "broken" a joint is. The Breakpoint simply indicates the maximum value the JointError can be before it breaks. When the JointError is greater than the Breakpoint, the joint (or spring) is automatically disposed and removed from the simulation. It's a very simple interface to work with.

As I add the breakpoint functionality, I'm also doing some api/code cleanup on the classes. Here is a list of all the joints/springs in Farseer. The items with the strikethrough have the breakpoint functionality added and are cleaned and ready for the release. (note: any spring or joint with "Fixed" in the name just means it is attached to the world rather than another body)

AngleJoint
AngleLimitJoint
AngleSpring
FixedAngleJoint
FixedAngleLimitJoint
FixedAngleSpring
FixedLinearSpring
FixedRevoluteJoint
LinearSpring
PinJoint
RevoluteJoint
SliderJoint

Finally, here is a video preview of the Farseer Physics Engine samples framework. Enjoy!

Making progress....

Mon, 27 Aug 2007 01:23:54 GMT

This has been a short work week for me as I was camping thur - sun. I did, however, manage to knock a few items off my list.

Here's where I'm at:

~~Limited Angle Joint (Joint limits for the RevoluteJoint)~~

~~Pin Joint with softness (60% complete)~~

~~Slider Joint with softness~~

~~Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)~~

~~Rewrite/Cleanup Collide method~~

~~Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)~~

Factory Objects

Make static classes
Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)
- Method(x, y, z)
- Method(simulator, x, y, z)

Breakable Joints and Springs

Queue-up Added and Removed items and remove them when it's safe to do so.

Joint API (just some general clean-up of the Joint objects)

User Data Object

General code clean-up

Docs!

New LOGO!

Website (bare-bones for now)

RELEASE!!!!!!!

Move on to my ultimate goal: Make some cool physics based games.

Wanting to be done!

Mon, 20 Aug 2007 01:52:59 GMT

Just another quick weekly progress report.

I'm done working on the new Joints (pin and slide). My "softness" implementation is still a bit suspect, but it's going to have to do for now as I don't have the time to dissect all the math.

Now I'm moving down the list. Hopefully I can start knocking these items off a bit quicker than I have been. I'm going camping this week (thur --> sun) though so I probably won't get much done till next week.

Here is the task list as it stands today:

~~Limited Angle Joint (Joint limits for the RevoluteJoint)~~

~~Pin Joint with softness (60% complete)~~

~~Slider Joint with softness~~

Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)

Rewrite/Cleanup Collide method

Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)

Factory Objects

Make static classes
Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)
- Method(x, y, z)
- Method(simulator, x, y, z)

Breakable Joints and Springs

Queue-up Added and Removed items and remove them when it's safe to do so.

Joint API (just some general clean-up of the Joint objects)

User Data Object

General code clean-up

Docs!

New LOGO!

Website (bare-bones for now)

RELEASE!!!!!!!

Move on to my ultimate goal: Make some cool physics based games.

Plus and Minus a Few Tasks

Mon, 13 Aug 2007 01:36:31 GMT

Well, instead of working through my list of things to complete and making the list smaller, I actually made the list longer.

I've decided to add two new Joint types and implement a "softness" factor on all the Joints. The two knew joints are Pin Joint (keeps two anchor points of two different bodies at a constant distance apart) and a Slider Joint (similar to the pin joint, but the anchors are allowed to move as long as they dont' go beyond some max distance)

I got the idea for the new Joints and some of the code from the Chipmunk Dynamics open source engine. It's a very cool "C" engine derived, like Farseer, from Erin Cattos Box2D engine.

Side note, there is a project on CodePlex to port Chipmunk to XNA. It seems to be just getting started but should be a nice when it's completed.

So, where am I at with my task list. Well it now looks like this:(strike thru means the item is complete)

~~Limited Angle Joint (Joint limits for the RevoluteJoint)~~
Pin Joint with softness (60% complete)
Slider Joint with softness
Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)
Rewrite/Cleanup Collide method
- Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)
Factory Objects
- Make static classes
- Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)
  - Method(x, y, z)
  - Method(simulator, x, y, z)
Breakable Joints and Springs
Queue-up Added and Removed items and remove them when it's safe to do so.
Joint API (just some general clean-up of the Joint objects)
User Data Object
General code clean-up
Docs!
New LOGO!
Website (bare-bones for now)
RELEASE!!!!!!!
Move on to my ultimate goal: Make some cool physics based games.

Light At The End Of The Tunnel... I Think!

Mon, 06 Aug 2007 02:28:17 GMT

I missed my weekly update last week because I was out of town on a camping trip.

I'm back now and I've made some progress on the physics engine. I think I can see some light at the end of the tunnel. I'm anxious to get this new release out so I can move on to new things.

Here is a list of the things I have left to do (this is an informal list taken from my whiteboard):

Limited Angle Joint (Joint limits for the RevoluteJoint)
Max Contacts To Detect, Max Contacts To Resolve, Resolve Deepest First (just some ideas I have about handling contacts)
Rewrite/Cleanup Collide method
- Replace collide event with callback/boolean return value (will allow the application to essentially cancel a collision)
Factory Objects
- Make static classes
- Overload as follows (If the simulator is passed in the object will automatically be added to the simulator prior to being returned. Just as a convenience)
  - Method(x, y, z)
  - Method(simulator, x, y, z)
Breakable Joints and Springs
Queue-up Added and Removed items and remove them when it's safe to do so.
Joint API (just some general clean-up of the Joint objects)
User Data Object
General code clean-up
Docs!
New LOGO!
Website (bare-bones for now)
RELEASE!!!!!!!
Move on to my ultimate goal: Make some cool physics based games.

Keep in mind I only have limited time to work on the engine (Mon-Friday: 4:45am to 6:30am) so progress is slow.... but very steady! If you are wondering why my time is so limited it's because I have a 6 month old son that seems to require my presence most the time I'm awake and not working. :-)

Here are a couple screenies of the latest demo added to the Farseer Demo Project. One without the simulator view enabled and one with it enabled.

Inching Along

Mon, 23 Jul 2007 01:57:53 GMT

Things were a bit slow this week. I got side-tracked doing some more performance tuning. The Joint code was not where it needed to be.

I've also just found a bug with collision detection. I'll be tracking that down over the next couple days. Once that is done, I'll be back to creating my Springs demo and then go from there.

I have decided I'm only doing 2 more demos after the Springs demo. Joints and something that involves many different things. If I don't limit myself to 2 more demos, I'll never get this thing released.

-Jeff Weber

Done with Collison Categories, On To Force Controllers

Mon, 16 Jul 2007 01:03:59 GMT

This week, I finished up the collision categories feature and sample. Here are some screenies of the final demo for this feature.

I've just started working on the next feature on my list, controllers. Controllers in Farseer are simple objects for applying forces to an object or objects. Springs are an example of a controller. All controllers inherit from an abstract Controller class. They then implement the "ApplyForces" abstract method however they see fit.

Controllers can be used for springs, explosions, steering behaviors, gravity wells, or anything else you can dream up that involves applying forces over time to a body or bodies.

The first demo involving controllers will show off the different types of springs:

Linear: regular spring between two bodies
Angular: attempts to keep a certain angle between two bodies
Fixed: used to attach a body to a world position

I'm still trying to decide what to put in the demo, but here is an early screenshot.

That's it for this week.

-Jeff Weber

Shall We Collide ?

Mon, 09 Jul 2007 00:16:05 GMT

Nothing really new to post. I've been working on the new features and samples. Currently I'm working on the new collision categories feature.

I am borrowing the technique used by the ODE engine... modified slightly to be more .Net friendly. Each Geometry can be set to be a member of up to 32 arbitrary categories. Each object can then define which categories it can collide with.

So for example say you defined your categories as such: Cat1 = Red objects, Cat2=Blue objects, Cat3 = Black objects.

You could then have a red rectangle geometry setup to be a member of Cat1 and able to collide with Cat2 and Cat3 objects. This would mean the red rectangle would collide with blue and black objects but not other red objects.... This system would also let you set up categories for things like walls that everything could collide with etc..

It's a pretty flexible system for defining collision behavior amongst geometries.

I haven't actually implemented it in the engine yet but I do have it scratched out in a small test app and I have a start on the sample that will show how to use it. Here is a screenshot of that:

And here is one from the same demo that shows what things look like with the new PhysicsSimulatorViewer turned on. I have everything turned on so the framerate kinda drops to a crawl. I wouldn't normally have the collision grid visible as it is the performance hog. The draw code could stand a little tuning. Here is the shot:

I'm still trying to get my to-do list off my white-board and into my computer so I can post it and let everyone see where things are at and what is left to do.

-Jeff Weber

Performance Tuning Farseer For The XBox 360

Sun, 01 Jul 2007 23:53:57 GMT

Well, it's been a week of trying to eek as much performance out of the 360 as possible.

Turns out the compact framework used by the XBox 360 does float math a fair bit slower than .Net on Windows. The good news is, this forced me to go through Farseer and tune the hell out of the critical performance path. I've got most of the high impact methods tuned and will finish the rest as I come across them while building samples.

Why is this good news? Because the engine really cruises on Windows now and it runs fast enough on the XBox to make some interesting game play.

The biggest performance bottleneck in the engine is simultaneous contacts. Anytime a scene contains a lot of stacked bodies, performance (especially on the XBox) will need to be considered. It is fortunate that there are a LOT of game ideas that don't require a large number of stacked bodies.

Here are a couple screens to give an idea of the performance difference (for stacked bodies) between the XBox 360 and my PC which is a Core 2 Duo, 2.13 Ghz, and 2 Gig of ram.

The physics for the scene on the right takes ~5ms to update on my PC, the physics for scene on the left takes ~5ms to update on the XBox. The XBox cannot run the larger scene.

Another way to look at it, considering just the scene on the left, the PC can update the physics in less than 1ms while the XBox takes ~5ms.

So, what now... well I'm back to upgrading the engine and creating samples/demos. I'll try to get a list of the things I'm working on posted so people can track where I'm at and how much I have to go.

-Jeff

XBox 360 Performance Woes

Mon, 25 Jun 2007 00:50:58 GMT

I spent the last few days performance tuning Farseer for the XBox 360.

I was not planning to do any performance tuning until I had everything else done, however the latest sample I created forced me to do it now.

The sample simply demonstrates stacking a number of boxes into a pyramid. It worked great on windows with a fair amount of boxes. When I ran the sample on XBox, expecting to get much better performance, the sample came to a crawl

Long story short, I've been researching best performance practices for the compact .Net framework and implementing them in Farseer. I still have a performance isssue on the XBox, but I think I know, finally, the cause. I'll be fixing it in the morning and then I'll know if I'm right.

Once the performance tuning is complete, I'll get back to implementing the rest of the features for the engine so I can get it released... and get back to making a game.

-Jeff

Simplifying Farseer

Mon, 18 Jun 2007 01:27:21 GMT

I mentioned in the last post that the next version of the Farseer Physics Engine will not be backward compatible with the previous versions.

I apologize if this causes any headaches. I made the decision to break compatibility in favor of simplicity of the object architecture.

The previous version of the engine had 3 main objects: The Body which handled the dynamics, the Geometry that handled the collision, and the RigidBody, which was designed to tie the Body and Geometry together.

For the new version, the RigidBody is gone! I decided it was not necessary and really just added to the complexity of the object model. The new version of Farseer has just a Body object and Geometry object. A Body object knows nothing about collisions. The Geometry object does. With the new version of Farseer, one to many Geometry objects can be attached to a Body (with offsets if desired) to give the Body a geometrical awareness in the simulation space.

I also mentioned in the last post that I created some "Factory" objects for creating Bodies, Geometries, Joints..etc... Below is a code snippet of how the new version of Farseer works.

//declare variables
PhysicsSimulator physicsSimulator;

Body rectangleBody;
Gometry rectangleGeometry;
...
//in the constuctor
physicsSimulator = new PhysicsSimulator(new Vector2(0, 0));
...
//create the body and geometry objects using factories
rectangleBody = physicsSimulator.BodyFactory.CreateRectangleBody(128, 128, 1);
rectangleGeometry = physicsSimulator.GeometryFactory.CreateRectangleGeometry(rectangleBody,128, 128);

And that's it. You may be asking where the Geometry was added to the Body. Well, that was done in the factory!

I'm out of time... before I go, here are a couple screenies of a couple more demos I've done for the Samples framework. (ignore the framerate, my screen caputure tool affects that... need to build screenshots into the framework)

Farseer Physics Engine Refresh (Coming Soon...)

Sun, 10 Jun 2007 11:53:39 GMT

For the past couple months I've been going back and forth on whether to keep working on my game, or take the time to release another version of my physics engine. I told myself I wasn't going to another physics engine release until my game was done.

Without going into all the details of why, I changed my mind and decided to take a small break from my game and update the physics engine.

First things first: This version I'm working on now will NOT be backward compatible with the previous release. There are to many things I wanted to clean up and for now, backward compatibility isn't in the cards.

So, here is a preview of what's to come. Some of these features already exist and some are new.

Farseer Physics Engine (Refresh) Features

Easy To Use!
Supports Both XBOX 360 and Windows
Full 2D Rigid-Body Dynamics with Collision Detection
Supports Both Concave and Convex Polygons
Multiple Geometries Per Physics Body with Offsets
Body, Geometry, and Joint Factories for Easy Object Creation
Collision Categories For Complex Interaction Between Physics Objects
Collision Events
Joints
- Revolute Joint
- Angle Joint
Linear and Angular Springs
Built In Debug Viewer To View All Major Physics Objects
Samples Framework With Samples Covering All Major Engine Features.
User Manual

Some of these are worth further mention.

I've built a Debug Viewer into the physics engine. The 'PhysicsSimulatorView' object makes it easy to see the detail of all current bodies, geometries, joints, and other miscellaneous details.

I will not release until I've documented all the core features of the engine. Here is a very small sneak peak at what that will look like:

I've created a samples framework to gather all my samples into a single application. This framework based on the Game State Management Sample and uses a separate "Screen" for each demo to make code-viewing easier. Here a some early screenies: (yellow objects represent objects you can control)

So, when will this new version be released you are probably asking yourself... or maybe not.

I don't have a hard release date. I'd say I'm currently about 50% done with the updates. My work hours are limited to a couple hours a day so if I had to guess I'd say it'll be a month or 2 before I have things ready to go.

Create Polygons From Images Tool Created By Ian Qvist

Wed, 06 Jun 2007 15:28:06 GMT

This is a very cool little tool that will generate code to create Farseer polygons from an image file.

Check it out here: http://ianqvist.dk/Polygonmapper/

Thanks Ian.

Farseer in Develop Magazine. Wow!

Thu, 31 May 2007 00:58:15 GMT

This caught me completly off gaurd. There is a small mention of the Farseer Physics Engine in the May 2007 issue of Develop Magazine. You can read it for free in .pdf format. Farseer is mentioned on pg 42.

Here is a screeen capture:

Blog Activity Coming Soon...

Tue, 10 Apr 2007 01:46:03 GMT

I've been working away on my game every spare minute I get. (Unfortunately I don't get a lot of minutes that are spare.) This is just a heads up post. I will soon be changing directions with this blog. Instead of being mostly about the Farseer Physics Enigne, it will be used as a development log for my game. (Which of course uses the physics engine.)

Stay tuned...

Focus on the game

Sat, 10 Feb 2007 00:33:15 GMT

It's been some time since I've posted. In case you are wondering what the heck I've been up to, well I've just been spending time working on my game engine layer and editor for my game

I've made some small tweaks here and there to the physics engine, but nothing to major.

I have added some debug visualizers to my game layer so I can see what's going on. It gives a good view of the inner workings of the collsion detection mechanism.

It's kind of hard to see in the image, but the yellow dots represent the vertices of the polygon, the white dots represent the distance grid, the green border is the AABB, and the black lines represent the polygon edges. There are also some red dots that reprsent collision but none are showing in the image.

Not sure when I will have another update. I think what is out there now is pretty stable for the time being. Sometime in the near future I will go after peformance tuning the engine and I'll release a new version then for sure.

Till then, have fun.

-Jeff

Farseer Video Tutorial On XNATutoral.com

Fri, 12 Jan 2007 04:19:32 GMT

Joran over on XNATutorials.com has posted a very cool video tutorial on the Farseer Physics Engine. You can find it here

He gives a very detailed description of the inner workings of the engine.

Happy New Year and a New Release!

Sun, 31 Dec 2006 14:30:56 GMT

First, Happy New Year to everyone.

I've just uploaded the latest release of the Farseer Physics Engine. You can get it here.

This release contains some older demos (4,5,6,7) that have been updated for XNA 1.0. It also contains a new demo number 8. This demo shows some of the newer stuff in this release.

This release also contains a change log which I will copy below for conveinence.

Have fun and as always let me know what you think.

Some screenies:

The change log:

Farseer Physics Engine Change Log

Changes For Version 0.1.0.0

FarseerXNAGame

· Refactored RectangleEntity, PolygonEntity, and PointEntity to inherit from a common base class: PolygonEntityBase.

· Added CircleEntity to go along with the other entity types.

· Made all private class level variables use the naming convention: _name

· Added a “RigidBodyDiagnosticEntityView” object to the Entities namespace. This object creates a diagnostic view of a RigidBody. Currently, it shows the vertices of the RigidBody and the collision points. (See FarseerDemo8)

FarseerXNAPhysics

· Added CollisionEnabled boolean property to RigidBody.

· Added CollisionResponseEnabled boolean to RigidBody. This will allow collision info to be generated without the bodies interacting physically.

· Modified PolygonRigidBody, RectangleRigidBody, and CircleRigidBody. Hopefully, the process of creating a rigid body and setting the way its collision grid is constructed is a little cleaner. I added a ‘CollisionPrecisionType’. If this value is set to “Relative”, the collision precision value will be multiplied by the shortest side of the rigid body’s geometry and this value will be used for the grid cell size. If the collision precision type is set to “Absolute”, the collision precision parameter will be used directly for the grid cell size. Currently, the Rigid Body Entities in the FarseerXNAGame project all use the “Relative” setting, but this change will allow for more flexibility if desired.

· Removed the PhysicsSimulatorBase class. It really wasn’t being used.

· Made all PRIVATE class level variables use the naming convention: _name

· Added RemoveJoint and RemoveSpring methods to the PhysicsSimulator class.

· Added Reset method to the PhysicsSimulator class. This method simply clears out all the list objects: RigidBody, Joint, Spring.

· Added CollisionEvent to RigidBody. The CollisionEventArgs object that is returned when the event fires will return a list of contact points.

· Added AngularJoint. This acts to keep 2 bodies at a specified relative angle. It is usually used in conjunction with a RevoluteJoint. Very similar to AngularSpring, but stiffer.

· Added Collide(Vector2 point) method to RigidBody. This adds the ability to check collision of a point with a rigid body. The method returns a bool.

· Added a “CollisonPoint” object. This object contains a boolean and a pointer to a RigidBody. It is used for doing collision tests between a point and the physics world. (see next bullet item.)

· Added CollidePoint(Vector2 point) to the PhysicsSimulator class. This method will return a CollisionPoint object. If the CollisionPoint’s “IsCollision” property is true, then you can use the CollisionPoint.RigidBody property to determine what body was collided with.

· The above two bullet points give the ability to do mouse dragging of rigid bodies. I’ve implemented a version of this in FarseerDemo8.

Heads Up...

Fri, 29 Dec 2006 15:26:27 GMT

Just a quick heads up. I've been working on a new release over xmas break. I should have it out tomorrow some time.

This release will include the much desired CollisonEvents... plus quite a bit of other stuff.

-Jeff

No More Bounce!

Sun, 10 Dec 2006 22:56:32 GMT

Well, I finally dug in and found the bug that was causing rigid bodies to bounce un-predictably upon collision. It was a simple mistake, but took me 6 hours to pin-point.

I've posted a new version of the physics engine on the Farseer Physics Engine code plex site. Just follow the link and go to the Releases Tab.

This release also contains a simple demo to show how things react with the new fix in place. It is important to now that when two bodies collide, the RestitutionCoefficient between them is taken as the average of the two. So, if you want no bounce then make sure the RestitutionCoefficient is 0 for both bodies.

This release also contains a project called FarseeXNAGame. This is a graphics/game layer that I am building for personal use. It is based somewhat on the Model-View-Controller pattern. Fell free to use it, but it is currently un-finished and may be changing a lot in the future.

Here is a screenie of the new demo.... nothing to exciting.

Very quick update...

Wed, 22 Nov 2006 03:21:05 GMT

Just a quick post to let everyone know I'm still working on the engine. I began working on the collision events, then decided I needed some drawing utilty functions so I can see what's going on. This has side tracked me a bit into creating a rendering system to sit on top of my engine.

I will be away for the next few days do to Thanksgiving. I'll pick up where I left off when I get back.

Another New Farseer Physics Engine Release

Sun, 12 Nov 2006 13:49:09 GMT

I just posted another physics engine release to fix up some known issues and some issues that came up in the forums.

Here are the details:

This is a physics engine only release. No new demos.

Updated PolygonRigidBody, RectangleRigidBody, CircleRigidBody, and PointRigidBody.

Rectangle, circle, and point rigid bodies now all derive from PolygonRigidBody.
Fixed up the constructors so that the collisionPrecisionFactor can be passed in if desired.

Updated all the Joint and Spring code.

RevoluteJoint now derives from the abstract Joint class.
LinearSpring and AngularSpring now derive from the abstract Spring class.
All springs and joints now support the Dispose pattern. Calling Dispose on any of these objects will instantly remove there influence within the physics world. If a body is disposed that is part of a joint or spring, then the corresponding spring or joint will automatically be destroyed.

Started help file:
I started creating a .chm help file. You can currently find it in the bin-->Debug-->Help folder. Not much there yet, just a few things in the "Body" class, but I'll be adding to it continuously.

That's all I can think of... Have fun and post in the forums if you have questions.

New Release... Sort Of.

Thu, 09 Nov 2006 00:06:59 GMT

I've uploaded a new release of the physics engine to CodePlex. This release has nothing new over the previous release except this time it includes the source for the physics engine. I forgot to add it last time.

In other news, the guys working on WildBoarders have posted some good info on there blog as well as a video showing the game in action.

In more "other news", Markus posted a link to his game Project Balance in the CodePlex forums. Looking pretty good so far.

As for the engine itself, I've got a few things to wrap up with the spring, angular spring, and joint objects. All are working pretty nice! I should have them finished this weekend. Next on my list is the collision event system so you can get some notification from the physics system when collisions occur. Lastly, I've got some general clean-up and .chm documentation in the works.

That's all for now...

New Release of Farseer Physics Engine

Sat, 04 Nov 2006 22:54:45 GMT

I updated 2 of my original demos for XNA Beta 2 and I added a new Demo showing some simple Joints.

You can get it here:

http://www.codeplex.com/Release/ProjectReleases.aspx?ProjectName=FarseerPhysics

Back From Vacation

Thu, 26 Oct 2006 11:32:32 GMT

Just a quick post to let everyone know I'm still around.

Over the next week or two, I'll be working on adding a spring system to attach bodies together. I'll also be re-visiting the collision response logic to make sure everything is working as well as it should be.

That's all for now...

Dispose Pattern, CircleRigidBody, PointRigidBody, and Some Raw Documentation

Tue, 17 Oct 2006 01:11:56 GMT

The physics engine has been progressing. I've implemented some the "Dispose" patttern on a number of the objects in the engine. The cool part about this is I was able to tie it all in so that calling dispose on any "live" rigid body will cause it to be removed from the arbiter list and from the rigid body list and then be clear for garbage collection. Put another way, call dispose on a rigid body and it and all it's affects in the world will disappear. If other objects are resting on it, it's as if the disposed object was pulled out from underneath it. Simple! the way I like it.

I've also fixed up some of the "primative" rigid bodies/geometries. I cleaned up the code a bit and added "CircleRigidBody", "CircleGeometry", "PointRigidBody", and "PointGeometry" object. The circle stuff is pretty self explanatory, it's just a polygon in the shape of a circle. The "PointRigidBody" is used to model a point mass, good for shooting at things!

I think I'll be disecting the collision response logic next. I have a feeling it's not quite right... close, but something seems a little bit off. I also plan to implement a spring/dampner system since it's a pretty easy thing to do and it allows for some pretty cool affects.

A first draft of documentation is up, you can get it here. Or just go to my CodePlex home page. Note: This is NOT help file style documentation, it is my attempt to explain what's going on in general terms.

Gotta run!

Dreaded Documentation

Tue, 10 Oct 2006 11:23:37 GMT

While digging through various XNA websites yesterday, I came across a post by someone using my physics engine for their game. In the post he said good things about the engine, but the thing that jumped out at me was the amount of time he had to spend digging through my code to figure things out.

So, that made me decide it was time to bite the bullet and throw together some documents to explain some of the more confusing parts of the physics engine. I will be putting this together over the next few weeks while at the same time continuing development. I'll post the documention on the code plex site as I get it done.

Next Steps

Thu, 05 Oct 2006 16:23:06 GMT

Just a quick post about what my next steps are with the Farseer Physics Engine (FPE).

I released the first alpha of the FPE last Sunday. I noticed it has been posted on a few XNA resource sites and received some positive feedback in the XNA and CodePlex forums. Thanks to all who commented and/or posted it on their site.

For my immediate next steps, I will just be adding more robustness to what already exists.

This includes:

· Some new RigidBody types to go along with RectangleRigidBody and PolygonRigidBody. (Both are simply extensions of the underlying RigidBody object.) This will probably include, CircleRigidBody, TriangleRigidBody, LandscapeRigidBody(2D only), etc…

· Expose some of the more advanced parameters in the constructors/properties of these higher level RigidBodies. There are a number of parameters in the RigidBody base class that are not currently exposed in the subclasses. These parameters control collision and collision response characteristics

· Misc. other logic changes/additions to increase robustness of the collision detection and response.

In addition to the working on the Farseer Physics Engine, I will also be putting some time in to my Farseer Game Engine which will utilize/wrap the FPE. In order to better flush this layer out, I will be building/releasing a simple mini-game that utilizes the existing features of both engines.

First Release of Farseer Physics Engine now on CodePlex

Mon, 02 Oct 2006 00:25:55 GMT

I just posted the first release of the Farseer Physics Engine on codeplex. You can get it in the 'Releases' section.

Here are some sceenshots.

Some Teaser Screens

Sat, 30 Sep 2006 14:04:50 GMT

I've got 2 Demos completed and one to go before I upload my Farseer Physics Engine for the first time. I should have everything ready to go for tomorrow.

Here are a couple screenshots from Demo2. ASDW, moves the "N" box around. Left, Right arrows applies torque(rotates) the "N" box. The space bar adjusts the gravity to: none, down, up, left, right, and back to none. (each press changes the gravity)

Getting Ready For 1st Release

Mon, 25 Sep 2006 19:41:39 GMT

I am currently getting things organized for my 1st release of the Farseer Physics Engine.

The 1st release will contain an alpha version of the Farseer Physics Engine as well as some simple samples to show how it can be used. I expect to have things ready to upload by Monday, October 30th

Stay tuned...