Can I move an object in the canvas along with the mouse?

According to the title,I want to move an 3d object in the canvas though a matrix using a move method.But the question is when I push the delta value,which is calculated by the newClientX substracting the lastClientX of event.clientX,as a parameter to the translate method,it can not match the Coordinate system of the webgl in the canvas.Because the mouse's position on the website uses pixels,so when I move the mouse a little,the object in the canvas will move so fast.Is there any method to fix the problem?

[huanghuan]

worldDelta = screenDelta * k. Experiment with different values of k and choose the one you are most comfortable with. It's up to your scene setup & personal preference.

[mrdoob]

Or, you can also reuse the code/approach from this example:
http://mrdoob.github.com/three.js/examples/webgl_interactive_draggablecubes.html

[zz85]

this reminds me that I should attempt work on DragControls sometime :)

the invisible plane + projector seems like a good solution, but i wonder if there's some sort of maths formula to do the same without the use of the plane?

http://mrdoob.github.com/three.js/examples/webgl_interactive_draggablecubes.html
it's a good example for me.thanks

I also want to deal with it though some maths formulas...But it seems to be too hard to figure it out

[chandlerprall]

@zz85 You can do this by getting the vector from the user's mouse position (normal projector.unprojectVector) and then determining what scalar multiplication needs to be done for that vector to reach a given 2D plane. For instance, if your vector is (0, -1, 0) and you want to reach the XZ plane where Y=1,

This is off the top of my head, not sure if the math is 100% - but I've implemented this logic in a few of my projects

camera = 0,10,0
v = 0,-1,0 // normalized vector from projector.unprojectVector
t = 0,1,0 // the target plane is along XZ where Y=1

camera.y + s(v.y) = t.y
s(v.y) = t.y - camera.y
s = (t.y - camera.y) / v.y

user_position = camera + s*v

Thanks~~I got it.I think I'll figure it out soon.