TGB particles, and such...

Hello all, long time since I got around to write anything here, been awfully busy (as usual I suppose).


In either case, what have I've been up to then? Well, also as usual, lots of stuff I can't talk about yet etc so let's just skip that. I have had a chance to work a lot with TGB lately though, which is perfectly fine with me. There's a lot of interesting ways to "cheat" when you're working with 2d art and effects...


The challenge

One of my recent challenges came when Jon Frisby needed nicely animated grass in his game Harmonic Convergence, I promised him to do a little write up about how I ended up doing it so I figured I might as well put it into a blog here. My first thought was of course to just create a number of animated sprites but I quickly realized this would both take me way too long to get it "just right", require a rather large amount of images to get the animation smooth and most likely have various issues with the animations being obviously looped and such.







Particles to the rescue
The solution ended up being particles! It's of course pretty obvious, but the way I ended up going about it may not be. You could use one particle per "strand", but this would quickly get prohibitive due to way too many particles. What I did was to create one(!) image frame of a couple of dozen of strands (fig 1). (it was created with the 3d studio max "hair and fur" system by the way (fig 2)). The fact that I only needed a single image to make the effect work of course saves on both resources (texture memory, download size and what not) and the time needed to produce the stuff.
Systems a go
This is the particle system I ended up with (don't worry, I'll explain what makes it tick in a moment), there IS a lot of "cheating" going on here. For one a particle can't have infinite life, like a piece of grass (at least not with the TGB particle system they can't). So the "sheets" of grass are constantly being faded in/out, the trick is to tweak the life, size and other parameters just right so it doesn't become too obvious.
As you can see by the image to the right our particle system will play infinitely, the particles will be spawned on the extent of the entity in the editor on the X axis (LINEX) and it's using our single frame grass imagemap for the particles.


Getting all the parameters correct will most certainly take some messing, what you want is a rather long life for your particles and a rather high quantity (not too high though, you have to balance this against the life of your particle so you don't get too many). Further you don't want your particles to move (since grass really doesn't "move" now does it?), you instead give them a tiny amount of spin (notice that I have the limits set to a very, very low amount in the image to the right).

























To make the fading in/out thing something you don't really think about I came up with this visibility graph.






Covering up
Due to the spinning of the particles the bottom of the effect will always look pretty horrible, so what do we do when something looks horrible? We cover it up of course! Just adding a big static sprite on top of the effect to make sure nothing shows that we don't want to and we're done.


Here's the finished effect in the TGB editor; I had to use two separate grass particle systems for this particular level (the stuff on the far right is a separate system).

In motion
And since all of this REALLY can't be made justice with just static images here's a video for you too! (it does look a bit sharper in the game, stupid video compression killing it a bit). All the levels in the video use the same basic effect with a few tiny parameters tweaked and the grass image switched out. As you can see you can get a quite different effect with only very minor changes.

www.blikstad.com/gg/grass_particles.wmv


Hope I've managed to show you you can do some very nice things with TGBs particles, this particular system could be used for a lot of things like fur or hair or whatever. I'm also using some very similar ideas to create animated water/waves and nice subtle light beams and such.


Other stuff...
In addition to working with Jon on Harmonic Convergence I've been working with some of the final things on GameSlingers TaeKwonDo World Champion... getting really close to release now.


Then of course we have all that secret stuff I'm not allowed to talk about, but well... as I said before, we'll take that another day... =)


I also of course have to shout out a huge congratulations to Josh and Lara on the pending wedding!













In conclusion
I'm finishing up some contracts at the moment, so, if you have any art that need to be done or any problems that need fixing feel free to take a look at my portfolio, my profile or simply fire off an email (magnus@witentertainment.com) and we'll talk.