Tuesday, August 31, 2010

Rect and Point Extension Methods

I'm currently working on multiple Windows Phone projects and don't have much time for longer blog posts, but I just wanted to get this out.
For one of the projects I need to calculate some simple vector arithmetics like the Euclidean distance. I also need other properties of the Point and Rect structs that aren't built-in the Silverlight framework. As you might know I'm a huge fan of extension methods for extending built-in functionality (12). That's why I wrote a few extension methods for the Point and Rect structs that might come handy.

public static class RectExtensions
   // Calculates the center point of this rectangle.
   public static Point Center(this Rect rect)
      return new Point(rect.X + rect.Width * 0.5, rect.Y + rect.Height * 0.5);

   // Tests if this rectangle intersects with the other.
   public static bool IntersectsWith(this Rect rect, Rect other)
      // Test for separating axis
      if (other.Bottom < rect.Top || other.Right < rect.Left 
       || other.Top > rect.Bottom || other.Left > rect.Right)
         return false;
      return true;

The usage should be pretty obvious.
Rect r = new Rect(0, 0, 200, 300);
Point center = r.Center();

bool isIntersecting = r.IntersectsWith(new Rect(500, 600, 100, 50));

public static class PointExtensions
   // Calculates the distance vector of the points.
   public static Point Distance(this Point p1, Point p2)
      return new Point(p1.X - p2.X, p1.Y - p2.Y);

   // Calculates the length of the vector.
   public static double Length(this Point p)
      return Math.Sqrt(p.X * p.X + p.Y * p.Y);

   // Calculates the square length of the vector.
   public static double LengthSquare(this Point p)
      return p.X * p.X + p.Y * p.Y;

The squared length saves some cycles if this information is only needed for comparison.
Point p1 = new Point(200, 300);
Point p2 = new Point(400, 500);
Point distance = p1.Distance(p2);

double length = distance.Length();
double lengthSq = distance.LengthSquare();
length = Math.Sqrt(lengthSq);

Source Code
You can download the two C# files from here.

Tuesday, August 10, 2010

Coding4Fun - Part 1 of the Windows Phone Picture Effects App and Roadmap

My new Windows Phone 7 article for Microsoft's Coding4Fun site is live. It's the first part of a short series about the development of a Windows Phone 7 picture effects application called "PicFx". The first article will show how to create the base Windows Phone application and how to implement some basic effects. The source code is licensed under the Ms-PL and can be downloaded from the CodePlex site.
I'm already working on the second part of the series, which will explain how to implement advanced effects (the cool stuff) and other features. After this article I'll add more features and important effects, enhance the existing effects and release it as "Pictures Lab" on the Marketplace.

The video below demonstrates the Coding4Fun PicFx application features and also shows how it can be used. It was recorded with the application running in the emulator.

Monday, August 2, 2010

Book Review - 3D Game Development with Microsoft Silverlight 3: Beginner's Guide

A couple of weeks ago I got a review copy of the book 3D Game Development with Microsoft Silverlight 3: Beginner's Guide. The book has 452 pages, is written by Gastón C. Hillar and shows how to write games with Silverlight.
Although the title includes "Silverlight 3", the concepts are also valid for newer versions of Silverlight, like the current version 4.
This blog post is a short review of the book. I also have one physical copy of the book to give away. Yeah, a free book, like free beer.

The Content
The book 3D Game Development with Microsoft Silverlight 3: Beginner's Guide starts by explaining what tools are needed for Silverlight game development. Then the first simple Silverlight application is developed.
The second chapter explains what Sprites are, how they can be used for 2D games and frame based animations. Silverlight 2.5D hardware accelerations is also covered and how basic vector transformations work.
The next chapter introduces a Sprite wrapper class and how to simplify the game loop with it. Basic 2D collision detection with an axis-aligned bounding box is covered too. The author also shows in this chapter how to use keyboard input for the game control.
Chapter 4 finally brings 3D game development. It starts with a WPF XAML Browser Application (XBAP) application that draws a 3D model, which was generated with the 3D modelling tool Blender and then exported to a XAML file. After this, the 3D engine Balder is introduced and a simple application is created. To be honest, Balder has come a long way since the book was written and a lot of new features were introduced. Nevertheless, many concepts and the basics are still valid.
The next chapter explains some 3D concepts like Cameras and shows how to use them with Balder and XBAP. The 6th chapter is about input controlling and demonstrates how to use DirectInput with the XBAP application. Chapter 7 explains textures, lights and the usage of these in a game. The next chapter is all about animation.
The 9th chapter introduces the Silverlight physics engine Farseer and chapter 10 shows how to detect collisions and apply basic artificial intelligence. The next chapter adds an asteroid belt to the space game, which is used as an example throughout the book.
In Chapter 12, the author shows how to measure the game progress and how to use Expression Blend to create screens for highscore and other statistics. The next chapter continues with this and also explains the usage of pixel shaders from the WPF Pixel Shader Effects Library. Persisting settings to the IsolatedStorage is covered too. The last chapter demonstrates how to play and control audio and video with the Silverlight MediaElement.

If you want to get into game development with Silverlight, this is the right book for you. It starts with the basic tools, then shows how to write a simple 2D game, finally how to write a 3D Silverlight game with Balder and how to add a physics system. Another nice thing of this book is that the tools and techniques to create / convert content are also shown step-by-step.
3D Game Development with Microsoft Silverlight 3: Beginner's Guide lives up to its title: "Beginner's Guide". If you are a beginner in the field of Silverlight game development and don't know where to start, buy this book here.

Free Book!
I actually got two physical copies of the book and I like to give one away. If you want the book, just write a comment why you should get this gift. Make sure to include some form of contact information.