Re: [Visualpython-users] Collision-check

[Hans-Joachim G. <gu...@gm...>]

>As you know, none of these kinds of checks are currently built into 
>Visual. One of the problems is that what you're asking for is not 
>very well defined. 

>> I would like to
>> * check if objects in a scene overlap,
>Overlap in the 2D projection on the screen, or overlap in 3D?
>> * check if an area in space is empty,
>Presumably you mean volume? 

I meant volume, and overlap in 3D.

>> * get a list of objects that occupy a given point or area in space,
>Area on the 2D screen? Or volume in the 3D space?

I was thinking of a function like objectsAt(0,0,0) that would
return a list of all objects that occupy that point in space.


>> * get the distance between objects
>"Distance between objects" is an ill-defined term. 
>Shortest distance between any two points in the two objects?

The idea was to check if two objects are about to collide.
I realize that this gets more and more difficult with the form
and the velocities of the objects. So probably too hard...


>> E.g. in the demo "bouncing ball", I would like to check 
>> if the ball touches/overlaps the floor-object, as opposed 
>> to checking a fixed y-value for reversing the motion.
>Note that in "stars.py" there is such a check, a check to see 
>whether the center-to-center distance of two stars is less than 
>the sum of the two radii of the two stars.

Ok, that is another example for the user doing the 'housekeeping'.
I was thinking that the infos about all the objects in the scene
must be available to the renderer, and could somehow be queried.


>> The empty-check would be useful for automatic placing of labels
>> (e.g. by varying the offsets if an area is occupied),
>> so that they don't overlap curves/objects/other labels.
>maybe you're most interested in area on the 2D projection.

I had the gcurve-example in mind. There the problem is reduced to 2D.
For placing readable, non-overlapping labels, checking their area on
the 2D projection on the screen would be enough (if that can be done 
more easily).

But if you want, for example, fill a volume with objects  such as 
in the randombox-demo, (but also with other things than just boxes)
and check that those objects don't overlap, a 3D-check would be needed.


Regards,
 HaJo Gurt
-- 
Experience is what you get when you don't get what you want.