[x3d-public] LineSensor

[Leonard Daly]

Doesn't  a PlaneSensor degenerate to a (proposed) LineSensor in the case 
where minPosition[x|y] == maxPosition[x|y] (min==max for either X or Y). 
The spec 
(http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/pointingsensor.html#PlaneSensor) 
essentially says that at the end of the 7th paragraph after the node 
definition.

Also rotation of the parent doesn't change the local coordinate system, 
just how it appears on the display. If the parent is rotated so that the 
local coordinate system has Z in one the screen primary direction 
(across or up/down), then all that would be generated is a line sensor 
-- changes in either X or Y (the one into the display) could not be 
detected.

Leonard Daly

> I now understand the need for LineSensor and may give it a try for
> x3dom. I know freewrl has it. It may make sense to replicate it.
>
> My initial idea would be to use the x axis of the local coordinate
> system as the Line orientation. Or maybe the y axis since X3D
> geometries tend to align along y (cylinder, extrusion).
>
> Then one can construct an intersection plane which includes the x axis
> and another direction at a high angle with the viewing direction to
> get a clean intersection for the inital point and subsequent points
> during dragging.
>
> Is that how freewrl does it ? I think I saw that it may use an
> additional field for the line orientation but it may be best to avoid
> it.
>
> Andreas
>

-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Past Chair
President, Daly Realism - /Creating the Future/
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