Re: advice on using Performer

New Message Reply Date view Thread view Subject view Author view

Rémi Arnaud (remi++at++remi.engr.sgi.com)
Thu, 11 Sep 1997 14:30:34 -0700 (PDT)

T. M. Murali wrote:
>
> Hi,
> I am planning to write a walkthrough application on top of Performer
> and would like some advice on the issues I am facing. I will be using
> an SGI Octane with two R10000 processors.
>
> The application will first read in an input model (say, containing
> only triangles) and construct a Binary Space Partition (BSP) for the
> model. For each frame, it will traverse the BSP in a depth first order
> that depends on the viewpoint, determine the triangles that are
> visible, and render them. The application uses some tricks to
> determine (a small subset of) the visible triangles and render only
> these triangles.

 Is there any reason why you do not use the Z-buffer ?

>
> It is unlikely that the triangles will need to be rendered in
> different modes. Most of them will be untextured and opaque, with
> attributes bounded per-vertex or per-triangle uniformly throughout the
> model.
>
> I need to be able to process each triangle to construct and traverse
> the BSP. It seems to me that I need finer access to the triangles than
> is provided by a pfGeoSet. Further, the order in which the triangles
> are rendered will be completely determined by the traversal. If I
> store the input model in a Performer scene graph, this order might be
> confounded by the order in which the pfGeoSets are normally rendered
> by Performer.
>
> One possibility I am considering is to read in the triangles into my
> own data structures and use OpenGL calls to render them. To use the
> multiprocessing support built into Performer, I can traverse the BSP
> in the APP process and render in the DRAW process.
>
> Another possibility is to create a new node called (say) pfBSP in the
> Performer node hierarchy. I could conceivably traverse the hierarchy
> of pfBSP nodes in the CULL process and do all the necessary processing
> using callbacks. However, it seems to be me that I still need to
> render triangles using OpenGL calls.
>
> If I am to take advantage of Performer's ability to draw pfGeoSets
> efficiently, I might have to create pfGeoSets on the fly. Is that a
> very costly operation? Typically, I expect to create many pfGeoSets
> for the first frame and only a small number in each subsequent frame.
>
> Are there any other options I should consider? Thanks for your help.
> Murali
> =======================================================================
> List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
> Submissions: info-performer++at++sgi.com
> Admin. requests: info-performer-request++at++sgi.com
>

    _ / _ _
|_) _ ._ _ o /\ |_)|\ | /\ | || \
| \(/_| | || /--\| \| \|/--\|_||_/
                                           
=======================================================================
List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
            Submissions: info-performer++at++sgi.com
        Admin. requests: info-performer-request++at++sgi.com

New Message Reply Date view Thread view Subject view Author view

This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:55:55 PDT

This message has been cleansed for anti-spam protection. Replace '++at++' in any mail addresses with the '@' symbol.