2D Angular Interpolation

It has been a while since my last post. I've done a lot of work with the Farseer physics engine and intend to write up a post on how I've managed to use the Tiled polygon tool to create static Farseer bodies that are loaded though Nick Gravelyn's TiledLib library.

Anyways I'm getting off topic. I just came across this stackoverflow question. I expected googling "2d angular interpolation" to give me a simple function I could pass on to the asker. However, I found few and they seemed overly complex so I wrote my own.

The concept is that I can lerp to either the angle specified or to the angle a full revolution from the one specified.

So for example if the object is rotated 50 degrees and the destination is 290 degrees. I add a second destination of -60 degrees.

Since 50 - -60 = 110
And 290 - 50 = 240
We know that rotating towards -60 is quicker and I simply lerp the current angle towards -60.

Anyways I hope that now anyone googling "2d angular interpolation" finds this a simple, easy to understand funtion to use.

Creating a Farseer Physics Body from a TiledLib map

(Please note I have found a much better way to do this. In fact I don't recommend you use this method at all. Expect a new post eventually.) I've been playing with TiledLib and Farseer and while doing so wrote some extensions to make integrating the two a bit easier.

The idea is to render a layer of a TiledLib Map to an image and then use Farseer's texture to poly tools to create a collision body. To do this I extended the TiledLib Map class to allow you to draw individual layers and save a rendering of the whole map to disk. Then I added a function that automatically creates a physics body from any giver layer.

There are some limitations to the above for example it only works on 1 object per layer, so split up your collision layers so that there is only one polygon on each layer. Fortunately, Farseer's textures to polygon tools seem to really like the consistency and uniformity that comes with a typical tilemap. Because of this I have had no problems so far with the tools failing to create a physics body.

Below is the whole class of extensions. Feel free to use it just keep the copyright notice up top.

PasteBin.com Class File

Embedding XNA Content in Compiled Code

I recently discovered that you can use the Content Pipeline in conjunction with a resource (as in .resx). This is very useful for embedding resources in a .dll if you need to ship your library with textures or models.

Compile any content you want with this project and add the resulting .xnb to your .resx.

Then create an instance of the ResourceContentManager class and load the content in the same way as you are accustom to doing with a content project.

Event driven input for XNA on the PC

XNA Input limitations:

XNA has a rather severe limitation with regards to handling keyboard input. It is unable detect any keystrokes that occur between pollings. Because of this if your game is updating at the default 60 fps there are 0.017 seconds between polls can be to slow for individual characters of memorized sequences such as "ing".

To solve this leidegren.se created a hook that is very easy to incorporate into your project. This post is to help you get set up and serve as a reference should you need it. Feel free to post any quirks you run into and I'll add them.

Here is how to set it up:

To initialize the hook.


After initializing the hook there are 9 events that it will trigger. The names are very self explanatory so I'm only gong to talk about a few of the quirks I have come across.


CharEntered returns everything that is a character including returns, backspace  characters, and the like. Also keyborad combinations such as Ctrl + C are represented as a single character which can be compared by casing the integer value of the character (for example Ctrl + x == (char)3). CharEntered repeats if the corresponding key is healed down, a behavior very useful for text boxes and the like.

Different types of delegates