Game: Asteroids

justinmimbs 2017-12-01 18:33:34 UTC #1

Hi Elm Discourse!

I made a version of the arcade game Asteroids in Elm.

https://justinmimbs.github.io/asteroids/

Possibly interesting features: the asteroids split where you hit them and move accordingly, asteroid shapes are randomly generated, and text is rendered without traditional fonts.

Using Elm to make a game was delightful.

Happy blasting!

brian 2017-12-01 18:44:28 UTC #2

this is the coolest! How did you do that?

justinmimbs 2017-12-01 19:07:21 UTC #3

Thanks, Brian! Roughly: 1) split the asteroid polygon by the line of the blast, 2) find the center of each new fragment, and 3) apply the impulse from the blast to each fragment.

github.com

justinmimbs/asteroids/blob/c932ee6586e47af1b185044c29216207363a9028/src/Level.elm#L392-L438


interactBlastAsteroid : Blast -> Asteroid -> Maybe ( List Asteroid, Generator (List Particle) )
interactBlastAsteroid =
interactBlastCollidable
    (\impact asteroid ->
        asteroid
            |> transformPolygon
            |> Polygon.split (impact.blast |> blastTrailPosition) impact.blast.position
            |> List.foldl
                (\fragment ( fragments, particles ) ->
                    let
                        ( fragmentPosition, fragmentRadius ) =
                            fragment |> Circle.enclose


                        fragmentPolygon =
                            fragment |> List.map ((flip Vector.sub) fragmentPosition)


                        forceVelocity =
                            impact.blast.velocity |> Vector.normalize |> Vector.scale impact.forceSpeed


                        ( fragmentVelocity, fragmentAngularVelocity ) =

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