Videogame Biscuit

As promised, here’s a tutorial on how to create a space nebula in The Gimp. It’s a bit experimental, and I must admit I can’t remember exactly anymore how exactly I created it. You really need to experiment a lot with it to see what different effects you can achieve. But let’s get started! The nebula consists of two layers. Start by creating a layer called “Blue nebula”. I added this layer to the background image file I use in Wasabi defense.
First of all, you need some sort of random cloud pattern. This is the trickiest part, because the various filters used can be a bit unpredictable. You’ll probably need to experiment quite a bit, and afterwards you probably won’t remember exactly how you did it. Here’s a good starting point: Filters -> Render -> Clouds -> Plasma with the standard settings. Next, Filter -> Render -> Clouds -> Difference clouds with X and Y size set to 16. This resulted in this ugly beast:

Next, the color is changed to blue with Colors -> Colorize and the brightness and contrast is adjusted until you like what you see. This is the part that requires lots of trial and error. I don’t remember exactly how I did it, but I ended up with this:

I duplicated this layer, named it “Red nebula”, changed the color to red (Colors -> Colorize) and hid it for now; we won’t need it for another few minutes. You now have a screen-filling bright blue cloud, from wich we’re gonna sculpt our nebula. Add a layer mask and edit it with the paintbrush tool to hide the parts of the cloud you want to remove. The advantage of this over the eraser is that you don’t actually erase anything, so it’s easier to fix mistakes. So after editing the mask, I ended up with this:

Since you want to see the stars behind the nebula, set the layer mode to “Addition” and the opacity to 40%. The result doesn’t look very bright, but remember you still have the hidden red nebula layer.

So next, you’re gonna do the same thing with the red layer. I’ve hidden the blue layer for the sake of clarity, but it probably works better if both layers are visible, so you see the effect of the two layers blending together. Here’s what the red layer looks like after editing the mask:

And here’s the final result, with both layers blending together nicely:

Of course, this tutorial is just a starting point. Feel free to experiment away with other colors, more layers, different blending effects and opacities, filters, …

Slowly but steadily, Wasabi Defense is crawling through the development process. Here’s the latest screenshot of my work:

The enemy pictured here is the second gunship. This ship actively tracks the player and fires bursts of plasma bolts. They always operate it pairs. One ship is hunting the player while the other one evades him. It works pretty well!
As you probably see, I also changed the background a bit. The density of the stars is a bit different and, most important of all, I added a nebula. I had no idea how to get started on this, but eventually it turned out quite easy and the result is, even though I say it myself, quite spectacular. Expext a tutorial on this very soon!

Level two is in development, so here are a few screenshots. First of all, another fighter. These guys come flying in horizontally and then pull up. Unlike the previous fighters, these don’t fly in some elaborate twisting formation but perform short, fast attack runs. The fighter swarm actually consists of somewhere between ten and fifteen fighters, but only three of them attack at the same time. The rest waits outside the screen, and when you take one out, the next one is sent in. Kinda like a Steven Segal movie!

And then there’s the first bomber. I haven’t implemented the bomb-dropping yet, but yes, that big sphere thingy it’s carrying is the bomb! Bombers function independently from the attack waves and appear at random intervals during the game. They are also the key to getting a great score. The deal is, a bomber carrying a bomb is worth a lot more than an empty bomber, or even the score of an empty bomber and its bomb (you can shoot the bomb after it has been dropped). And they can destroy your base!

Whew, I finally managed to get some actual work done this week. I got the gunship up and running and managed to create a working first level. And, another important feature has been added: a soundtrack! I’ve done some searching on Jamendo, a website full of Creative Commons licensed music, and I have found the perfect game soundtrack: “Another One” by Ghostfog. Here are a few videos of the game in action:

Wasabi Defense combat level 1 from Videogame Biscuit on Vimeo

Wasabi Defense level 1 combat, part 2 from Videogame Biscuit on Vimeo

I have also created a sort of warp-in effect, as you can see in the videos. A problem with the way I calculated the paths for the fighters was that they appeared in the middle of the screen, and it was very difficult to make them enter the game outside of the screen. So I decided to try something different: make them teleport into existence! And I think it looks pretty cool!

Once again, I’m in game developer hell. Short on time all week, and struggling with the artwork. With two fighters done, I got started on the first gunship. Gunships are slower than fighters, but can take more damage and have more powerfull weapons. As usual, I started the design with some sketches on paper. While watching tv. Over the past few months, I seem to have developed the ability to watch tv and draw at the same time. After watching Grounded For Life, That 70’s Show and Dharma & Greg (in that order), I had some sketches that looked quite fine. So I fired up Inkscape and started drawing, but for some reason they looked quite stupid on the screen! Okay, so all those sketches were useless. Starting all over again, and it wasn’t until this morning that I finally came up with something usefull. Here’s what it looks like:

The central sphere, with the cannon, rotates to aim at the player, while the engine pods stay horizontal. This is only the sprite, it doesn’t do anything yet. They will always operate in pairs, and fire bolts of blue plasma at the player.
Another word on the problem of generating paths for the enemies to follow. I think it sucks bigtime that the path object included in Torque doesn’t work. You can’t seem to get smooth movement with a curved path. I hope this problem will be solved in one of the next versions. For the fighters, I have already come up with a very good solution, in the form of plotting a path with trigonometric functions. I have found a function that does a pretty good job at generating random looking paths (gonna explain how I did it in one of my following posts) and the result looks impressive. For the gunships, I’m gonna try something else I’ve been testing. These enemies actively try to evade the player instead of following a preset path.