Pick up 3dPoint in canvas

[juan974]

Hi all,
I m new to programing.
I m learning python at work, and at home : i m writting my first ruby code for sketchup.
To start it, i need a method to pick points (magnet to entities in model), lock to inference and type length in vcb.
The only thing i can do is to pick 2d points from screen with :

def onLButtonDown(flags, x, y, view)

For now my code works with UIbox in which you enter value.
All advice is welcome

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plugin

[juan974]

Finaly i achieve the plugin for a straight stair.
It's easier and it's a good way to learn ruby.
To draw a stair :
-install the file FaStair-i_Shape.rbz with the SU extension installator
-activate the tool named FaStair-i_Shape in the Plugins / Extension menu
-pick the origin of the stair
-pick the width
-pick the depth
-finaly pick the height

et voila

plugin FaStair-_i_Shape

Now i'm working on the FaStair-L_shape, it's much more complicated.