Silverlight 5 introduces new support for hardware accelerated 3D which makes it possible to create truly unique experiences. Unfortunately, the 3D API provided is very low-level, and probably not easily picked up by the average developer.

In this blog post, I’ll show you how to leverage existing libraries and tools to (relatively) easily create a 3D Physics based game or simulation using the new 3D features of Silverlight 5.

[DOWNLOAD SOURCE] [VIEW DEMO] * REQUIRES SILVERLIGHT 5 BETA 1 *

To accomplish our 3d scene and physics, we’ll be using two open source libraries:

1.       Balder 3D Engine: this engine was created by Einar Ingebrigtsen and allows Silverlight to load and display 3D models. Balder has been around for quite some time, but because of the lack of native 3D support in previous versions of Silverlight, performance was very limited. With the addition of native 3D support in Silverlight 5, much more is possible with Balder.

2.       JigLibX Physics library: this 3D physics engine has had many incarnations. It started as a C++ physics library, and was later ported to C# and XNA. Since there is no official Silverlight version of JigLibX, I created a slightly modified version of JigLibX with thanks to the great start on this work item.

Creating the 3D Models

There are so many different 3D model formats out there, it can be quite overwhelming. 3D Studio (.3DS), Wavefront (.OBJ) and Lightwave (.MDD) are just a few. Balder requires a model be in an ASE format (ASCII Scene Exporter), which is a popular format for 3D game frameworks.

Many tools can convert to ASE format, including the free Blender modeling software. You can download Blender 2.5 Beta here, and there is a Python script for Blender which enables ASE exports here. Also, MilkShape exports to ASE and can import a bunch of different formats and is just $35 US.

Balder also supports texture mapping of ASE models, but just be sure the texture is in either JPG or PNG format (often, modeling software uses a BMP format which Balder cannot display). You also need to make sure the reference inside the ASE file is correct for the texture file.  ASE files are just plain text, so you can open up the file in an editor and look for any BITMAP references like this:

                     *BITMAP "crate.jpg"

Displaying the Model

Once you have a model in ASE format, we can display this in Silverlight using Balder. The author of Balder has a great Getting Started Video which I recommend you watch if you are new to Balder. This video was created for Silverlight 4, so there are a couple of notes to keep in mind when using Silverlight 5 and the new version of Balder:

·         Be sure to Enable GPU Acceleration. This is required for Silverlight 5 to display 3D scenes. Add the following to the parameters of the Silverlight plug-in object:

<param name="enableGPUAcceleration" value="true" />

·         Sometimes you may see a “white screen of death” – that is, nothing is rendered to the window when using 3D. You can use the following properties to determine what’s up when that happens (but usually it is because you didn’t enable GPU acceleration as above).

Microsoft.Xna.Framework.Silverlight.GraphicsDeviceManager.Current.RenderMode
Microsoft.Xna.Framework.Silverlight.GraphicsDeviceManager.Current.RenderModeReason

Adding Physics

The job of the physics engine is to determine collisions, position, rotation, and the forces upon an object. We then take that position and rotation information and update our Balder 3D objects each frame.

I chose to use JiglibX as the physics engine, but there are several others that will no doubt make their way to Silverlight 5 in the near future. To get a quick overview of how JiglibX works, I recommend using the Basic World Tutorial.

If you take a look at the sample code, you will see that I sub-classed several of the Balder Geometries into Physics based classes. These wrap together both the visual Balder model and the JiglibX physics logic:

·         PhysicsBox displays a cube shape and is based on Balder.Objects.Geometries.Box. On the physics side, this uses the JigLibX.Geometry.Box class.

·         PhysicsCapsule displays a capsule model, like a pill shape. There is a special model for this, Capsule.ase. On the physics side, this uses the JigLibX.Geometry.Capsule class.

·         PhysicsRagDoll is the most complicated class, and creates a rag doll based on a whole bunch of other primitive objects including sphere, capsule, and box. This class was ported from the original JiglibX demo game.

·         PhysicsSphere displays a sphere model, using the sphere.ASE model. Note that Balder does not have a sphere primitive at this time, so that is why we need to bring in a custom model. On the physics side, this uses the JigLibX.Geometry.Sphere class.

Each of these classes implements an IPhysicsObject interface, which provides a Draw() method. This way we have a common way of updating the visual model with the underlying physics library data.

Adding Camera Control

For controlling the camera, I converted a class provided in this XNA Tutorial. This tutorial by Pete Street walks through basic camera control, so I suggest you read through it for the details. After the Camera class does its magic, we simply need to tell the Balder Camera where to move and point towards. This is done in the UpdateViewMatrix method of the Camera class:

_gameCamera.Position = Utils.VectorXnaToBalder(position);
_gameCamera.Target = Utils.VectorXnaToBalder(target);

Terrain Mapping

Terrains in a 3D physics game are often created using a Heightmap.  A heightmap is just a 2D bitmap image, where brighter pixel values represent higher elevation than dimmer pixel values. This 2D image data is then handed off to a 3D engine (or physics engine), and a corresponding model is created from the map. If you want to try creating a random heightmap, you can use a tool like Paint.NET to render clouds (in Paint.NET, just create a new image and select Effects/Render/Clouds).

Both Balder and JiglibX have support for heightmaps, so we are in luck! In the sample code you can see there is a PhysicsHeightMap class to handle feeding height data to a JiglibX Heightmap Collision Skin. The Balder Heightmap object is fed the same data through its HeightInput event in the MyGame class. I had some issues instantiating a Balder heightmap from code, so I designed the PhysicsHeightMap class to instead accept an existing visual heightmap object.

Summary

Although 3D in Silverlight 5 is very low level, we don’t have to be 3D experts to implement fantastic experiences using this new API. Instead, we can leverage existing open source libraries to get a quick start on 3D applications.

These basic 3D capabilities of Silverlight 5 borrow a great deal from the XNA Game Library. One has to wonder if all of XNA will eventually be implemented in Silverlight, making it a powerful development framework for everything from 3D games to business applications!

If you are interested in creating physics based Games for Windows Phone 7, you might find this useful:

Creating an Air Hockey Game for Windows Phone 7

I created this tutorial for the Expression Toolbox Site, using the Physics Helper Library and the Farseer Physics Engine. The design assets for the game were created by Pixel Lab. The tutorial consists of several videos and source download which walk you through creating this fun physics game!

There are also some other great Windows Phone 7 Tutorials available on the .toolbox site:

Calculator and Daily Awesome show you some of the design-side of Expression Blend. And Golf Tracker shows you how to creatively display and handle data.

Boss Launch 2: Zombie Attack is now available on the Windows Phone Marketplace.

It's the zombie apocalypse, and your only ammunition against the walking dead is an office chair and your fat, lazy boss. Launch your obnoxious leader at waves of oncoming flesh eaters in this fun physics game. Three episodes containing 42 total levels take you through office, city, and country environments. Launch your boss onto vehicles to crush your enemies, and use grenade power-ups for that extra touch of destruction.

Boss Launch 2 is FREE, but this may change in the future, so go out and grab your copy now!

Last night at the CNY .NET Developers Group, I presented a talk titled "Windows Phone 7: Monetize your Apps" where I detailed my WP7 revenue numbers and tips on monetization. Many of my fellow WP7 developers such as Farseer Games, Occasional Gamer, and many others have shared their sales as well.

In this blog post, I'll repeat my sales and ad revenue for my apps that I have on the marketplace. You can also download the slide deck for my presentation.

TALKING RAGDOLL

"Talking Ragdoll" has been in the Top 100 paid apps for awhile, it now hovers around #82. This is a little physics toy that allows you to import your enemy's face onto a ragdoll and then throw various objects at it, dress it up, and place it in different scenes. The ragdoll will also repeat what you say in a funny voice. This app was selected for LG's hAppiness campaign, and while I'm sorry I can't share the numbers for that particular opportunity, I will share the numbers for Marketplace sales below.

TALKING RAGDOLL STATS 11/8/2010 thru 1/24/2011
Type	Paid with Trial
Category	Entertainment
Trial Downloads	4274
Number Purchased	1280
Conversion Rate	30%
Developer Take	$896

As a "thank you" to its Windows Phone customers, LG is giving away 10 different apps every 60 days. The aptly named "hAPPiness" campaign has its own Facebook page which showcases the selected apps.  

I'm happy to announce that "Talking Ragdoll" was selected for the recent group of apps!

If you own an LG Windows Phone 7 device, you can go to the LG app store and download Talking Ragdoll for free, for the next 60 days.

See here for a full list of the other apps offered in this round, including the challenging physics game Krashlander by Jeff Weber.

In the coming weeks we should hear some more promotions centering around LG's "hAPPiness" campaign. For now, if you're an LG device owner, go out and have some fun, complements of LG!

UPDATE 1/9/2011: 1800POCKETPC has a nice video walkthrough of most of the apps featured in this promotion from LG.

[DEMO] [SEE A VIDEO WALKTHRU] [INSTALLER] | [SOURCE CODE]

Note that if you are alreay using the Physics Helper and upgrading to 4.2, you may encounter a few minor breaking changes in the Farseer Physics Engine. These are outlined on the Farseer download page under the Breaking Changes section.

Also check out all of the great New Features that the Farseer team has introduced in this version, including great performance enhancements!

If you are new to the Physics Helper, be sure to view the Intro Video and read through the Docs to get started.

Earlier this week I was sent a fun new toy – an EXOPC Slate running Windows 7. I was a bit skeptical about how well Windows 7 would work in a tablet form, but I was pleasantly surprised to find this is a great little device. Don’t get me wrong, there are a few quirks that come along with Win7 on a slate, but overall the experience is fun.

Unboxing the EXOPC

The EXOPC comes in simple, attractive packaging and includes a power adapter and Getting Started Manual. The device itself weighs just over 2 pounds and has an 11.6” capacitive touch display. It might be a little bulky for an e-reader, but I did find it very comfortable to handle.

We all know that MIX and PDC are historically premiere venues for unveiling important new Silverlight features, but it looks like Microsoft is really promoting the Silverlight Firestarter on Thursday, December 2nd 2010 - including a keynote by ScottGu and online streaming of the entire event!

[REGISTER FOR ONLINE EVENT]

So if you are interested in the Future of Silverlight, I have it under good authority that this is not to be missed!

Today I released a new version of the Physics Helper Library, which makes it easier to create Silverlight 4 and Windows Phone 7 games using the Farseer Physics Engine.

Here are the highlights for this release:

• Now supports Version 3 of the Farseer Physics Engine
  • Bullets
  • Continuous Collision Detection
  • Resting Bodies
  • see the Farseer project page for more details on this release of the Farseer Engine!
    
• Installer (msi) makes setup easier

[DEMO] [SEE A VIDEO WALKTHRU] [INSTALLER] | [SOURCE CODE]

I am very excited about the great work that the Farseer team did on version 3 of their engine. They sort of went back to the drawing board and brought in enhancements from the Box2D Physics Engine, which Farseer spawned off from long ago.

In the past, it was possible to hit tunneling problems (objects colliding and sticking together) with Farseer, and lack of support for resting bodies made large worlds difficult. But with the new enhancements, these issues have been resolved!

Please note that this is an initial Alpha version of the Physics Helper 4.0, and given the big change in the Farseer Engine, you can bet that there are some bugs and things yet to be implemented. But I have been using it for my latest creations and feeling quite productive with it. Be sure to view the Intro Video and read through the Docs to get started.

My first two apps for Windows Phone 7 are now on the Marketplace!

My Experiences with the App Hub

This past Monday (Oct 11, 2010) Microsoft unveiled its new developer portal for submitting applications for Windows Phone and Xbox 360 Indie Games, http://create.msdn.com. I was lucky enough to get early access to Marketplace Submission, and wanted to share some of my experiences.

Ian Walker has posted some great tips on his blog as well, so be sure to check those out.

While the process was pretty simple and smooth, it wasn’t without issues – in fact, as I write this the portal is down entirely! But keep in mind that this is the first real world test of the App Hub and they are most likely shaking out the bugs.

Icons + Panorama Image

Be sure you have all of your icons ready as specified in the Marketplace Submission Guidelines. You'll need 99x99, 173x173, and 200x200 PNG format Icons, and they need to be the same image. Folks have had their submissions rejected because of different icon imagery. Also, avoid any transparency in your icons, because they will show up as white in the Zune client until the user hovers over them (thanks to Rene Schulte for that tip)

The Panorama Image should be 1000x800 pixels (there is still some old docs lying around that state otherwise, ignore them). The pano image is shown as your background in the Zune client when the user drills into your app using a link like this: http://social.zune.net/External/LaunchZuneProtocol.aspx?pathuri=navigate%3FphoneAppID%3D74e401d0-8ad5-df11-a844-00237de2db9e

If you are lucky enough to have a "featured app" (which I think equates to a top seller in a category), then your Pano image will also be featured as the Marketplace background for that category. Be sure that you do not include any text or title in your Pano image. The Marketplace UI does that for you.

Watch Your App Sub-category

This is something I hosed up when submitting my game. When you select the Category, it is easy to miss the Sub-Category drop-down next to it. Be sure to select this because even changing something as simple as this requires a full re-submission! 

Take Your Time and Plan

Really be sure that you take your time and get your verbiage right for your app description. Note that the app description CANNOT contain any formatting such as CR/LF or HTML breaks. This is a reall bummer and I hope they fix that soon because you can't really list out your app highlights in a bulletted list.

Same thing for your icons and images. Currently any tweaks at all to an image or text requires a full resubmital.

Turn-Around Time

Microsoft is shooting for "5 days or less" for approval of your apps. Because I participated in the early access program, my turn-around times might not be typical. But both my apps were approved in less than 2 days.

Get Ready for Feedback

This is something that many developers might not be used to: Immediate feedback on your creation! Once your app is on the marketplace, people can add reviews which I find can cause huge mood swings. For example, when I submitted my first game I saw this review come up:

Woohoo! Thank you. I did a little jig around the house. But then, some more reviews started popping up:

What is really frustrating here is that you cannot reach out to these people and help them, or ask them for more details. Why is the app taking too long to load? Do they know that the game has a "How to Play" tutorial in the Option screen? You'll never know because reviews are a one-way street.

Also note that there are very few WP7 devices out there in the world right now (I've heard just 2000 or so?), and guess who has those devices? Fellow developers --- probably your harshest critics!

Get Help

To be honest, I saw little or no help coming from Microsoft on the App Hub Forums, which was a bit frustrating. Maybe their hands are full with the App Hub early trial. But it did help to commiserate with fellow devs on the Forums who were having the same issues you were. It's great to know that you are not alone when something is awry!

Summary: Have Fun!

I have had a total blast since I first heard of Silverlight being the premier development platform for Windows Phone 7! If you've followed my blog, you know that I am a hobbyist game developer and have been creating casual games in Silverlight since the SL 1.1 Alpha (see them here). Like me, I hope you concentrate on having fun with WP7 and sharing your apps with others. And who knows, you might make a little money, 99 cents at a time!