It’s about how you can record and playback player inputs to generate game replays. Check it out, and let me know what you think.

For example, the player’s walk animation has been the same for months. I was happy with it, and had moved on to other things. As soon as I linked the video, many developers reported that they didn’t care for the animation, and pointed out ways I could make it better.

We took the suggestions to heart, and made a bunch of changes. He’s now taller, and has smaller shoes, which doesn’t force him to shuffle so much. Also his shoes now bend when they should, so it looks more natural.

I think the results are a pretty drastic improvement, and I’m really happy with the changes. Have a look, and let me know what you think.

It looks like youtube has fixed the slowdown bug, and they’re reprocessing the videos. So if you see anything funny on my older embedded videos, please try back in a little bit.

We’re having some technical difficulties with the videos we posted on Youtube. The video is running at half speed with distorted audio. Youtube says they have engineers working on the problem. So for the time being, I’ll post my update videos on Vimeo, instead. (I don’t have a paid Vimeo account, so I can’t embed high def, but you can see the high def version over on Vimeo.)

Hero In Training – Progress Update August 5, 2010 from Jesse Chounard on Vimeo.

What we need:

1. Foot position of the player. (Bottom center of the player’s collision rectangle works well.)
2. Line segment we’re checking for collisions with, specified by its end points A and B.
3. Player’s velocity.

Let’s get to it:

1. Is the player moving down? If not, we can stop here.
2. Is the player’s expected position (foot position + velocity) within the horizontal region of the segment? If not, we can stop.
3. Calculate the interpolated Y position on the line segment of the player’s X position both before and after the move.
4. If the Y position before moving is above the segment, and the Y position after moving is below, then the player is landing.

And today I’ve put together a quick sample project to go with that. You’re welcome to do whatever you want with the code. (License – Ms-PL.) I hope it’s helpful. Feel free to hit me with any questions.

Here’s a video:

Bullyfrog is a frogman who simply runs across the screen. If he reaches the edge of a ledge, he’ll leap to the next ledge. (If he can reach.) He’s really quick, and not very easy to dodge. I think we’ll do a palette swapped version of this character who is a bit tougher and will stop to throw projectiles at the player.

Spikey is a big spike covered block who waits for the player to get near and then smashes down trying to squash them. I added a neat screen shake effect when he hits. He’s completely immune to boomerangs, they just bounce off of him.

I was left with two options:

1. Add the ability to attach textures to the custom objects in Tiled.
2. Change to a different level editor.

Option one sounds reasonable, and the source code is really clean and pretty easy to edit. But I’d need to add a bunch of functionality to support rotation, scaling, and draw order for the textures. It would take me awhile. After spending so much time on Demina, I’m very tired of working on tools. I want to write my game!

So I asked my friend Google for help, and I wound up finding Gleed2D. I’ve spent a few days playing with it, and it seems really nice. It supports all of the features I was looking for. It has support for a few primitive types, so you can set up region boxes, or collision polygons pretty easily. You can attach custom properties to any element into the editor, so the automatic game entity creation system I used with Tiled works perfectly without much change. It also has support for parallax layers right in the editor. Nice!

There is a pretty big drawback to Gleed2D, though. The creator uploaded a flurry of updates during July of last year, and then went silent. On the forums (if you dig through the heavy spam) are a bunch of requests for updates or access to the source code. But there’s been no response. This isn’t an insurmountable problem, since the editor is in an easily usable state, but it still stinks.

It took me a little while to get it up and running, since I had to rewrite the collision system to allow for slopes, but it’s looking pretty nice. Here’s a new work in progress video. (The graphics are just random stuff I had lying around.)

So I made my own, and I made it open source, so anybody can use it. It’s called Demina.

Using it, we’ve managed to make a little progress, and I can finally show you a work in progress video. There’s not much to see yet, but now that the animation system is usable this game should really start taking shape in the next few weeks.

Comments are welcome.

I’m beyond thrilled with what she’s done so far, and I’ll share more as I can.