Subject:
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Re: Math Help Needed PLEASE
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Newsgroups:
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lugnet.cad.dev
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Date:
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Mon, 19 Jun 2000 12:45:55 GMT
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Viewed:
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1995 times
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In lugnet.cad.dev, Michael Lachmann writes:
> Hy,
>
> I'm running into math problems again, after I recogniced whats the problem
> with the movements in MLCad. Now here is what I would like to do:
>
> There is a virtual grid which is bound to a part. The distance of the grid
> lines is given by a vector 'GRID' [x-spacing, y-spaceing, z-spacing] (e.g.
> default for coarse grid [10, 8, 10]. This grid rotates together with the part
> so a rotation-matrix 'RM' is available. I assume the origin of the grid to be
> the same as the origin of the part and the offset is a vector 'OFF'.
> Now the user views the part (and invisible) the virtual grid seen from a
> certain side given by the view-rotation-matrix 'VM'. If this matrix is [1,0,0
> 0,1,0 0,0,1] the part and grid is show from FRONT.
>
> The user can move the move the part in x and y direction (which actual axes
> depend on the view-rotation-matrix). I need to know where is the nearest point
> on the grid for a given screen point 'PS' [x, y, z] (translated into model
> space already)
>
> I sum. everything now:
>
> Given is a vector 'GRID', a rotation matrix 'RM' (for part and grid), a view-
> rotation-matrix 'VM' and a screen point 'PS'.
>
> Searched the snapped screen point 'SPS' which is snapped to the nearest grid
> point.
Transform PS from model space to unrotated part space.
Round the x, y, z values to the nearest grid points.
(add half a grid size, divide by grid size, multiply by grid size)
Transform PS back to model space.
I think this algorithm may be covered by the GPL though. You'll have to
publish your source if you use it ;-)
Don
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Message has 1 Reply:
 | | Re: Math Help Needed PLEASE
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| How embarrassing. Please ignore my previous post. Apparently Lars beat me to it and even brought up a point I missed. Now I have to go figure out how to retract a message. Don (26 years ago, 19-Jun-00, to lugnet.cad.dev)
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Message is in Reply To:
| | Math Help Needed PLEASE
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| Hy, I'm running into math problems again, after I recogniced whats the problem with the movements in MLCad. Now here is what I would like to do: There is a virtual grid which is bound to a part. The distance of the grid lines is given by a vector (...) (26 years ago, 19-Jun-00, to lugnet.cad.dev)
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