[GEM-dev] view for gemwin

[ben at ekran.org]

Hey Jamie,

I think the simplest solution (perhaps for the next release) would just be
to add view support to change the pivot point/rotation of the camera. So
you could just specify the 0,0,0 point as the pivot, place your camera and
point it at the pivot and then rotating the camera accordingly. A camera
object would be pretty cool, how would you attach the view to a particular
camera object? It would be nice to be able to use the same translate and
rotate objects as with any other geometry... It may be confusing without
an objective view though, so you can see the camera's relation to the
scene, rather than looking through it...

I've never heard of this gimbal lock issue, I've written a simple little
3D renderer in SDL that just plotted points on a 2D surface. I used:

x' = cos(za)x + sin(za)y
y' = -sin(za) + cos(za)y

etc.. I then rotated around each axis consecutivly. I did hear about uding
quaternions for this stuff, if you go that way I'd love to see the code.

Is gemmouse aimed to be ported for the next release?

Later
Ben



> On Wednesday, September 3, 2003, at 12:55  PM, ben at ekran.org wrote:
>
> hey ben,
>
> ...I've also been working on some better camera-type support, but
> haven't settled down to a particular solution...on the one side, we
> should be able to create an abstraction that works thru view messages
> to gemwin...on the other side, perhaps we need a full [camera] object;
> this could then have a fps-type control mode with input for
> forward/backward, strafe left/right, up/down, and roll: and a "follow
> object" mode, which allows rotation around a particular point...I've
> been looking into different ways to calculate rotations:  using sin/cos
> can result in "gimbal lock", which is incorrect rotation after multiple
> similar rotations, or quaternions, which are complex numbers used to do
> matrix multiplies...
>
> ...as far as the patch goes, it looks nice, but reminds me that
> [gemmouse] isn't working on OSX...
>
> l8r,
> jamie
>
>
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