Picking question...I think.
I have an application that shows some fairly complex 3D models. I need to allow the user to select a point with a mouse click, drag the mouse to another point on the model, then calculate the linear distance between those two points. In other words, I don't need to know the distance across the surface of the model (the curve), just the actual distance of the line between the points.
I assume that this is just a picking related question, but as I have never dealt with picking before and guidance on this would be greatly appreciated!
Also, can someone recommend a good tutorial on picking? I know that it has changed since the time when my Selman book was written!