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Elysia game moving platform character

Topics: Developer Forum, User Forum
Feb 7, 2012 at 9:56 PM

Hey all I work for whisper game studios, and we're developing elysia (youtube link here: and we have a character called whisp. He's essentially a moving platform that the player controls in addition to quiff, our main character. We're using farseer as our physics engine, but I'm having so much trouble trying to get this to work. Without any extra coding, quiff stays on whisp when whisp moves along the Y axis, but as soon as whisp moves left or right quiff falls off. I've tried using a fixed prismatic joint, but that gave me some really weird behavior. If someone could show me the proper way to do this I would really appreciate it!

Feb 8, 2012 at 3:43 PM

Woudn't a weld joint be a better solution? Altghough from the physics point of view perhaps playing with the friction between the characters is closer to the real world.

Feb 8, 2012 at 3:59 PM

I've never heard of a weld joint. Is that in Farseer 3? We're using XNA, so I'm not sure if we only get certain aspects of farseer. Could you provide some example code?

Feb 8, 2012 at 7:15 PM
Edited Feb 8, 2012 at 7:19 PM

Farseer 3.x is based on Box2D with some extensions so you can use the Box2D manual:


A weld joint basically glues two bodies together. It's a constraint that restricts both angular and linear motion between the bodies. As for code it's actually the simplest joint, only that box2d a few versions ago made it "soft" so for example you can't make a perfectly stiff rod from rectangle elements just with weld joint (it will bend a bit). But that's not your case anyways.