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Update the Second!: Physics, Gravity, and Trigonometry

Update #3 · May 23, 2012 · 6 comments

Helloooo everybody!

Here's the rightnow lowdown on the uphigh: The project has received over $3000 from 140 backers with 9 days left to go. That is a LOT of haikus that need to be written! (plus at least two bobcats to catch...)

I've just finished moving, and things have settled down enough for me to really start working on Rubicon in earnest. For instance, over the weekend + Monday + Tuesday, I gave the physics engine an overhaul, which allows for pretty little things like black holes (soon to be joined by grappling hooks/tractor beams!):


(music by Sanjay)

For those of you who are interested in the process of coding the game:

Working on Rubicon is just a CONSTANT re-crash course in trigonometry. Let me regale upon you the sordid tale of updating the physics!

The demo faked a lot of things in the interest of gameplay (things didn't have mass, as per se; collisions used maximum armour to calculate momentum, all the ships had hardcoded acceleration/maximum speed). Of course, in order to have gravity/spring effects, I'd need to put the actual underlying machinery in place. It shouldn't be too hard, I thought- coding 2D physics is relatively straightforward, and most of the time doing so was just killing all of the obsolete workarounds.

But wait! If thrusters provide a constant forward force, everything accelerates up to obscene speeds and it's impossible to tell what's going on. Fake physics for the sake of gameplay are required: once the ship approaches some set maximum speed, have the thrusters provide less and less force.

But wait! That makes it impossible to redirect the ship once you get up to that speed, since your thrusters no longer work. So that means that I need to only look at the speed vector parallel to the angle of thrust, as far as decreasing the efficacy of the thrusters.

So, net problem: I need to take an absolute angle (and force), compare it to the parallel vector of another absolute angle (and speed), and reduce the force according to how close that vector is to a maximum speed.

But wait! This makes it impossible to steer finely- if you're thrusting at an angle close to the one you're moving at, the new thrusting force is almost zero. So I need to keep track of speed-altering and angle-altering forces separately... and so on.

TL;DR: dammit, Jim! I'm a neuroscientist, not a mathematician. :D This is the sort of problem-solving I love about making games.

Comments

    1. Fb_profile_picture.small

      Creator Ben Puliafito on May 24, 2012

      Pshhh, math.

    2. Beaticon.small

      Creator Beatscribe on May 24, 2012

      You lost me near 'but wait!' :S Glad you understand all that mathination..

    3. Lucy-11.small

      Creator Lucy Bellwood on May 23, 2012

      WHOMAGAWD. You blow my mind, Wick. Keep kicking ass.

    4. Missing_small

      Creator Gabriel on May 23, 2012

      Cool black hole! Can't wait to play with it.

    5. Skj_avatar2_128x128.small

      Creator Veav on May 23, 2012

      Oh, this is going to be a fun summer for you. You've scratched the surface. }:D

    6. Rachel_facebook_photo.small

      Creator Wick on May 23, 2012

      And by "update the second", of course, I mean "update the third".
      ...
      I hear that in some cultures those are the same thing?

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