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Game in 7 Days, Day 2: Boom boom boom boom!

Posted by ManTis, in Programming, 7days1game 14 December 2013 · 836 views

artillery programming ludumdare warmup 7d1g
Day two is done!

Since I had a long day at work yesterday, the coding had to be moved to today. At first, my goal was to make full collision, physics and movement for the character. That proved bit too much to be done in one day. As always when faced by huge wall, I got bummed out and played around with graphics and effects Posted Image

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Basically, this is a single octave Perlin noise generation. I've also added dirt tiles for underhangs (I think it looks really sweet now, even if graphics is temporary and put together in couple minutes) and slime/squid alien thingie as a player character. Because, as Shakespeare said, everybody loves slime/squid alien thingies Posted Image.

I've later added bit more complex and customisable level generation. Apart from possibility to go multiple octaves, for more jagged look, I've also added option for controlling amount of terrain appearing, changing between more vertical and more horizontal levels, and some other tiny knobs that you can twist for cool effects:

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Then I returned to working on physics. Since there was no implementation of per-pixel collision for Unity anywhere online, I had to put together one on my own.

I've solved this by dividing problem into wide and narrow phases, for optimisation purpose. First, broad phase. I take AABB (axis aligned bounding box) of the object I'm moving in the Origin position, AABB of place where it will be, int the Target position, and wrap both of them in one AABB, like this:

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Then I take this big boundaries AABB and iterate over every pixel within level geometry that is contained within this box, and check if it's solid (nonzero alpha). If so, I procede to narrow phase: for each solid pixel that could be encountered, I fire a ray in the direction that is opposite to movement direction, which means that only the pixels who are on direct route will fire a ray that will collide with origin box. If such points in the map are found that the rays for them hit the origin AABB, the one closest to the origin AABB is chosen as collision point, and the function returns.

That sounds complicated but is necessary for pixel perfect collision, and that is what I need if I'm going to make Artillery game. Again, like I said, since this took me quite a while and I needed to take care of baby, and now I need to sleep, for now the game will be oldschool Artillery, with no movement for the squids. Once I had the collision code I could quickly hack together a physics code and add some explosives to be thrown. No special effects yet, just canonball that has gravity, and when it detects collision with ground, explodes destroying everything around it. Here's the result:

Posted Image

You can see holes in the ground to the right of our brave alien hero. I understand that static images can't really show how awesome this is, so here's a tiny .MOV file (click) that shows level destruction. Now on to day 3!

Story so far:

Day 7
Day 6
Day 5
Day 4
Day 3
Day 2
Day 1




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