Jetboard Joust Devlog #17 – Beam Me Up, Dotty

More going over old ground as the game starts to develop it’s own visual style. It’s annoying but necessary – one has to take an organic approach to these types of things I think. Really I should stick with placeholder art and work on the design almost completely separately from the gameplay (as if I was working with another artist) but I find it very hard to do that. Consequently I’ve wasted at least two or three days so far which is kind of frustrating. Hey ho!

Anyway, the latest thing to be redone is the new life/appear animation. I did have the main character being shot from a Mario-style pipe as you’ll see here but that didn’t really seem in character any more. I wanted something more spacey and in keeping with the feel of Defender which is my main inspiration for Jetboard Joust.

So I started work on a ‘teleport’ effect. I knew I wanted the main character to dissolve into a kind of pixelated fog and the most appropriate way to achieve this seemed to be through a custom shader – down the HLSL rabbit hole again.

I started by creating a shader that reduced the pixel resolution of the drawn texture. I split the texture into a series of chunks and took a sample from the centre of each chunk which was returned as the colour to draw. Having no HLSL experience it took a while just to get to this stage. I have all my animations on sprite sheets so each sprite drawn is generally a small portion of a much larger texture, HLSL works with coordinates relative to the full texture (regardless of the region being drawn) so initially the results I was getting were pretty random (when they weren’t completely blank) but when I figured out to pass the coordinates of the cropped region to the shader and do my calculations based on that instead things started to progress pretty quickly.

Initial results were promising (though somewhat static) and the effect looked like something I could progress with. I added some motion by sampling from a random point in each chunk rather than the center (I do this every other frame) and a kind of ‘spark’ effect by inverting the colour balance every so often (currently every four frames). I also added the ability to sample from a smaller portion of the texture than that being drawn, effectively scaling up the sprite. Then I added the ability to set the alpha for the entire shader allowing it to fade out smoothly.

We were getting there now! This was all the functionality I really needed from the shader and the next stage was setting up some tweens in my main game code to control the various parameters. There’s quite a few tweens chained together in the final result, one controlling the sample size, one the scaling and one the transparency. I wanted it to look like tuning into a radio station sounds with big adjustments at the start (no reception) and small ones at the end (finding the point of best reception).

Once I was happy with that I added some more particles, trying to keep things fairly stylised looking. A small change to the particle generator was required to allow for imploding particles. There’s also a pixel particle generator which blurs the edges of the actual texture (this looked a bit too obviously square at low sample sizes).

And now I think almost done. Only thing that’s really bugging me is the very dark pixels from the shader when they get large, these look a bit too glitchy (not in a good way). May have to knock these back a bit or something. And there’s something about the small explosion/implosion particles not quite sitting right with the larger pixels – I might need to make these particle fx more ‘pixelly’ somehow…

One HLSL thing that had me stumped for a while was that, whilst I was tweaking and commenting out bits of code, the C# code that set an effect parameter in the shader suddenly started throwing a null pointer exception indicating that that parameter was no longer present in the shader. WTF? Turns out that, though I hadn’t removed the parameter declaration in the shader, I’d removed all references to it in the actual code so the compiler was optimising it out (doh)!

It may also interest you to know that I did all this thinking ‘Defender’ had a similar ‘implosion’ effect when the player’s ship appears – but it turns out it doesn’t at all – neither does the sequel ‘Stargate’! Damn childhood memories deceiving me.

Dev Time: 0.75 days (including project setup)
Total Dev Time: approx 18.5 days


Attempt #1

Attempt #2

Attempt #3

Attempt #4 – Almost Done(!)

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