Dynamically updating vertex coordinates on a Mesh' Geometry?

Hi,

Im trying to update the vertex coordinates on the geometry of a (custom) mesh by doing this on some loop callback:

<meshvar>.geometry.vertices[idx].position.y = someNewYVal;

however the render on the screen is not showing the modifications. My question is whether this should work and the error is somewhere else… or is there anything I need to do to ‘invalidate’ the mesh geometry?

Thanks!

[mrdoob]

It’s now geomety.verticesNeedUpdate.

[nvjkmr]

I’ve a similar problem. I’m still a noob. I have created a 3D cylinder geometry with a set of 2D points using LatheGeometry class. Now I have a small sphere in the scene. What I want is, when the sphere touches the cylinder, I want a groove in the surface of the cylinder at the point of collision. My question is, if I find the collision point using Raycaster, then how do I get to the point (that I defined in 2D) and change the geometry?

Or do I have to do it in some other way? And another question is, if I get to the point (that I defined in 2D) do I have to redraw the cylinder using LatheGeometry?