Forums » Help » Adding Shapes to Physics body at runtime Using Box2D.js

I'm trying to add shapes to a physics body at runtime as a result of some player action. I can add the new shape and that works fine, but I cant seem to set the new shapes position relative to an existing shape or really set the position at all. The new shapes are just getting stacked on top of each other.
Suggestions?

I believe you have to manipulate the shape's vertices "by hand". See this blog post and the documentation.

I.e. something like this might do (untested):

var shape = new b2.PolygonDef();
shape.SetAsBox( 20 * b2.SCALE, 20 * b2.SCALE );
		
var moveX = 10, moveY = 20; // new relative position
for( var i = 0; i < shape.vertices.length; i++ ) {
	shape.vertices[i].x += moveX * b2.SCALE;
	shape.vertices[i].y += moveY * b2.SCALE;
}

That did it, Thanks for the help. Impact is a great engine.