Drawing 3D curve with varying width

I am trying to draw a curve in 3D in which the width may vary. I am doing something similar to what described in the following tutorial: http://www.merowing.info/2012/04/drawing-smooth-lines-with-cocos2d-ios-inspired-by-paper/#.U1QkTOaSy-T

Meaning, i create quads (and triangles) with the desired width instead of using OpenGL width. The problem is that the triangles are actually in 2D - they are drawn in a specific plane. The width will look different, of course, from different angles.

Am i tackling this problem in the correct way? Is there a good solution for my problem?

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