Re: Modifying GeoSet Geometry...

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John Rohlf (jrohlf++at++tubes)
Mon, 9 Jan 95 11:30:54 PST

>
>
> I am trying to modify the geomety (polygon vertices) of a pfGeoSet
> object and have not found a solution for doing this yet.
>
> I initially know of a several polygonal objects(say a pyramid and
> cube) and I want to create 100 clones of the original objects, but
> each having their geometry altered from the original model. For
> example, depending on a certain parameter, the height of one pyramid
> might be higher than another cloned pyramid. I have investigated the
> following two solutions with no success:
>
> 1) I create the object in Performer by first creating a new
> pfGeoSet and setting the geometry of the object using:
>
> pfGSetAttr(gset, PFGS_COORD3, PFGS_PER_VERTEX, poly_list, NULL);
>
> where poly_list is a list of my geometry. Next, I set this pfGeoSet
> to a new pfGeode. I create a pfGeoState and pfMaterial for this
> pfGeoSet and give color, etc. This solution worked fine, except that
> when the object gets rendered, it is flat shaded. It has no shading at
> all, just a solid color.
>
> Any suggestions?????

         
        For lighting, make sure your geoset has normals, and
        you've set up a pfLight, a pfLightModel, and you
        have enabled lighting with pfEnable(PFEN_LIGHTING).

> 2) I created master objects using i3dm and save the objects as sv format.
> When I use the sv loader, the objects are shaded correctly, but I
> cannot get access to their geometry. In order to make each cloned
> oject with its own geometry, I don't use pfClone, because, as I
> understand it, pfClone doesn't copy the object geometry. Therefore
> I use pfCopy for the objects pfGeoSet, pfGeoState, and pfMaterial.
> Once, the object has been completely copied, I querey the geometry
> list with:
>
> pfGetGSetAttrLists(gset, PFGS_COORDS3, (void**)poly_list, (ushort** i));
>
> The contents of poly_list is all zeros, not the geometry, yet when I
> querey the number of vertices and triangles in the pfGeoSet, the
> correct values get returned, I just a cannot get the old geomtry.

        pfCopy copies geoset arrays by reference rather than by value.
        I don't know why your list is all zeros but you'll need to
        clone the arrays yourself:

        newCoords = pfMalloc(pfGetMallocSize(poly_list),
                             pfGetMallocArena(poly_list));

        pfCopy(newCoords, poly_list);

        pfGSetAttr(cloneGSet, PFGS_COORD3, PFGS_PER_VERTEX,
                                        newCoords, NULL);

        Hopefully in the next release pfClone will handle geometry.

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