April, 2010

This article is prerecorded. Shawn is away (getting married later today). Replies to comments will be delayed. Plagiarizing my MIX talk , I thought it would be useful to summarize the performance implications of choosing between the different shader permutations...

This article is prerecorded. Shawn is away (getting married at the end of the week). Replies to comments will be delayed. Remember the story about the chessboard and the grains of rice ? Shader programmers have the same problem. We start with a bunch...

The BasicEffect API and feature set did not change in Game Studio 4.0, but the implementation saw some aggressive optimizations. In previous versions, BasicEffect was intended as a starting point for beginners. We expected expert programmers to soon move...

Where in previous XNA versions you used to write: effect.Begin(); effect.CurrentTechnique.Passes[0].Begin(); DrawStuff(); effect.CurrentTechnique.Passes[0].End(); effect.End(); With Game Studio 4.0 this becomes just: effect.CurrentTechnique...

In previous XNA versions, a VertexBuffer was just a loosely typed bag of bytes. A separate VertexDeclaration object specified how to interpret these bytes. As of Game Studio 4.0, every VertexBuffer now has an associated VertexDeclaration, which is specified...

Game Studio 4.0 includes some tweaks to simplify common patterns when working with Viewport objects. We added two constructors: public Viewport( int x, int y, int width, int height); public Viewport(Rectangle bounds); And we added a Bounds property...

I often refer back to internal design documents and bug databases while writing these "what's new" blog posts, but it rarely makes sense to quote directly from them. In this case, though, the existing text seems clear enough that I shall simply...

I like to think I know what I'm doing with computer graphics, so I find it embarrassing that it took us four versions to get something as fundamental as alpha blending right . To cut a long story short, I didn't properly understand alpha blending until...

As of Game Studio 4.0, the default alpha blending mode is now premultiplied rather than interpolative.   Why? I was fed up of repeating this conversation: Customer: Why do I see ugly borders around the edges of my sprites ? (or sometimes: Why does...

Every now and then, a Game Studio 3.1 customer tries something like: spriteBatch.Begin(SpriteSortMode.Immediate); SetRenderStateFoo(); spriteBatch.Draw(...); SetRenderStateBar(); spriteBatch.Draw(...); But this does not work! Sadness...

Improvement #1: Our Sprite Effects sample uses SpriteSortMode.Immediate to draw sprites with a custom pixel shader: // Begin the sprite batch, then activate our custom effect. spriteBatch.Begin(SpriteBlendMode.None, SpriteSortMode.Immediate, SaveStateMode...

The theory: SpriteBatch was designed to provide an easy and efficient way to draw 2D sprites. Everything it can do, you can also do yourself by creating vertices and calling the lower level Draw* APIs, so our goal with SpriteBatch was to make the most...

Steve Hazen has some great articles about the kind of math used in 3D game programming: Matrix Basics. How to step away from storing an orientation as '3 angles' Working with and Visualizing Vectors Be sure to follow the links in that second article ...

The most-often-linked-to article I ever wrote is about renderstates, so it should come as no surprise that we tried to improve this area in Game Studio 4.0. There are fundamentally only two sane ways to manage renderstates: Assume nothing: explicitly...