Hi Theo,
As for the coordinates, I can see where you are going but I still don't know
how can I know the boundaries of my camera view on the xz plane. I mean, if I
use the ortho projection I can set it and my viewport to the size of my screen
and I'll know exactly what coordinates the boundaries of my camera will be. So
if I draw a point to 1024,768 I'll know it will be on the corner of the screen.
How can I do the same thing using the perspective projection?
Well a rectangle in 2D space will become what's known as a frustum in
perspective-projected 3D space, i.e. a truncated pyramid. You can simply
unproject your viewport's 4 corners (top-left, top-right, bottom-left
and bottom-right) to get the frustum's 8 corners, using the same math I
posted before. As you can see, that will give you two 3D points per 2D
point, one near and one far. You can also do the opposite.
Then given that frustum you can find out where to place your objects.
I suggest you look up 3D projection math on Google, you will get more
details. In particular I like this page, very complete and easy to
navigate with the bar at the top: http://www.euclideanspace.com/
Hope this helps,
J-S
--
______________________________________________________
Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com
http://www.cm-labs.com/
http://whitestar02.webhop.org/
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