T w e n t y S i d e d

I worked at Activeworlds for a lot of years. Activeworlds is a social / gaming world along the lines of Second Life or Roblox. It’s a virtual world with user-made content. The experience gave me some interesting phobias regarding CPU cycles.

Perhaps some anecdotes would help. For the sake of argument, let’s say these are all taking place around 2003 or so.

Joe User is building himself a virtual office in Activeworlds. He wants dark windows with a heavy tint, but the object library only has these windows with 50% transparency. Joe doesn’t understand transparency. He’s not a graphics artist or a programmer. He’s just a regular person, and to him tinted windows are tinted because they’re “dark”. He tries changing the color of the window from the default blue to black, but confusingly it doesn’t help. He can still see through the window just fine.

He makes a copy of the window to try another color when he has a eureka moment. Looking through both windows – one in front of the other – really makes a huge difference. What’s really happening is that the first window is blocking 50% of the outside color, and the second window is blocking 50% of the remainder for a final opacity of 75%. Joe doesn’t know this. All he knows is that this looks nicer. He makes another copy, and it’s better still! This is clearly the key to success. Two more windows perfect the look, giving him an overall opacity of 97% or so. He’s got five windows stacked up here. He nudges them so they’re only a centimeter apart.

If you’re a professional, your eye is probably twitching by this point. This isn’t art, it’s sabotage. Alpha surfaces (like our partly transparent windows) must be sorted before rendering. It’s a constant struggle to limit the number of transparent surfaces you’ve got in the scene and you want to be very careful about situations where the user will end up looking through multiple alpha polygons at the same time. The program has to get the distance to each surface, then shuffle them around and put them in order from furthest to closest before they can be drawn. All of this work must be done by your CPU. (Maybe new graphics cards have some trick for this, but in 2003 this load went right to the CPU.)

But that’s not the bad part.

Continue reading ⟩⟩ “Project Good Robot 4: The Clock”

Shamus Young is a programmer, an author, and nearly a composer. He works on this site full time. If you'd like to support him, you can do so via Patreon or PayPal.

A quick reminder that while I’m writing this in the present tense (easier for me than switching tenses) we’re actually looking at this game as it existed three weeks ago. My first code check-in is dated July 29, so we’re visiting the past right now. If things go the way they usually do, then this series will eventually catch up to the present, since coding tends to slow down as a project grows.

So I’ve got my world of random walls and I’ve got a little avatar I can fly through it. I guess next we should work on AI. But to work on AI we need some foes. Well, there’s no sense in adding foes if they can’t attack me, and I don’t want to debug both AI AND shooting mechanics at the same time, so I should add shooting first. Of course, shooting will require collision detection. And to add these things to the scene I need textures for it all so I can tell one thing from another.

I’ll be using one texture for all the foes and projectiles in the game. In old 8-bit games this was called a sprite sheet and it looked like this:

Continue reading ⟩⟩ “Project Good Robot 3: Killer Robots”

Shamus Young is a programmer, an author, and nearly a composer. He works on this site full time. If you'd like to support him, you can do so via Patreon or PayPal.

So now we’re working in 2 dimensions. The advantage is that 2D development is a lot easier than 3D. The disadvantage is that I don’t have the right tools for the job.

If you’re making a game or some other kind of 3D-rendering type stuff, then you need some basic variables and tools. The first thing you’ll want is some sort of geometric vector. Like, if you’re going to be using x, y, and z values then you probably want some way to bundle them together. With a proper vector toolset we can have this bit of code:

Continue reading ⟩⟩ “Project Good Robot 2: Welcome to 2D”

Shamus Young is a programmer, an author, and nearly a composer. He works on this site full time. If you'd like to support him, you can do so via Patreon or PayPal.