-----Messaggio originale-----
Da: pli...@li...
[mailto:pli...@li...] Per conto di deepha sv
Inviato: sabato 3 dicembre 2005 6.37
A: pli...@li...
Oggetto: [Plib-users] scenegraph structure
> hi,
> I am using a simulation software ,as we are reading the data file =
and
storing into a scenegraph tree structure=20
>=20
> 1. how are we actually taking the data from the scenegraph and placing =
it
in frustrum.
By means of the camera positioning and actual drawing.
sgCoord camera; // has xyz (camera position) and hpr (camera =
orientation)
fields
// ...
// set camera.xyz and camera.hpr as your camera motion model
// ...
ssgSetCamera( &camera );
ssgCullAndDraw( scene ); // scene is your scene graph root
Anyway there are other camera placement approaches in SSG, e.g. by 4x4
camera matrix, or by a LookAt approach (the one showed is somehow a =
LookFrom
instead).
> 2. how and where , are we placing the frustum in scenegraph
Where: at window resize time (i.e. within the resize callback if you're
using Glut)
How:
ssgSetFOV( fov_x_deg, fov_y_deg ); // frustum hor & vert =
field-of-view
ssgSetNearFar( nnear, ffar ); // frustum near, far
Or, if you need an explicit frustum control (calculating frustum params =
it's
up to you):
ssgSetFrustum( left, right, bottom, top, near_clip, far_clip );
Modern SSG syntax want frustum things to be set as methods of a =
ssgContext,
and set it as current context.
> 3. how the data from the frustum are rendered.
The actual drawing occurs at the ssgCullAndDraw call.
> for preparing scenegraph and rendering i am using plib library.
Welcome on board.
As usual with apparently simple questions I hope to have interpreted =
your
questions in the intended meaning.
Greetings -
Paolo Leoncini
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