From: Yigang Wang (yigang.wang++at++gmd.de)
Date: 12/06/2000 00:48:51
Hello,
If you like, i hope you to see the program
/usr/share/Performer/src/pguide/libpf/C++/intersect.C. The pfGeoSet is a
Cube-similar object, which is made by 6 QUAD faces. I change the
representation of each face with strips , so i have 6 strips instead of a
single strip, and length of each strip is 4. In the original case ( not
changed by me), the parameters corresponding to PFQHIT_PRIM and PFQHIT_TRI
changed correctly, that is, prim_index changed with intersection points.
However, it doesn't change after my changing.
Here is what i have made change to the pfGeoSet.
Original,
pfVec3 *verts = (pfVec3*) new(8*sizeof(pfVec3)) pfMemory;
verts[0].set(-1.0f, -1.0f, 1.0f);
verts[1].set( 1.0f, -1.0f, 1.0f);
verts[2].set( 1.0f, 1.0f, 1.0f);
verts[3].set(-1.0f, 1.0f, 1.0f);
verts[4].set(-2.0f, -2.0f, 0.0f);
verts[5].set( 2.0f, -2.0f, 0.0f);
verts[6].set( 2.0f, 2.0f, 0.0f);
verts[7].set(-2.0f, 2.0f, 0.0f);
ushort *vindex = (ushort*) new(24*sizeof(ushort)) pfMemory;
vindex[0] = 0; vindex[1] = 1; vindex[2] = 2; vindex[3] = 3; //
front
vindex[4] = 0; vindex[5] = 3; vindex[6] = 7; vindex[7] = 4; // left
vindex[8] = 4; vindex[9] = 7; vindex[10] = 6; vindex[11] = 5; // back
vindex[12] = 1; vindex[13] = 5; vindex[14] = 6; vindex[15] = 2; //
right
vindex[16] = 3; vindex[17] = 2; vindex[18] = 6; vindex[19] = 7; // top
vindex[20] = 0; vindex[21] = 4; vindex[22] = 5; vindex[23] = 1; //
bottom
pfVec4 *colors = (pfVec4*) new(4*sizeof(pfVec4)) pfMemory;
colors[0].set(1.0f, 0.0f, 0.0f, 0.5f);
colors[1].set(0.0f, 1.0f, 0.0f, 0.5f);
colors[2].set(0.0f, 0.0f, 1.0f, 0.5f);
colors[3].set(1.0f, 1.0f, 1.0f, 0.5f);
ushort *cindex = (ushort*) new(24*sizeof(ushort)) pfMemory;
cindex[0] = 0; cindex[1] = 1; cindex[2] = 2; cindex[3] = 3;
cindex[4] = 0; cindex[5] = 1; cindex[6] = 2; cindex[7] = 3;
cindex[8] = 0; cindex[9] = 1; cindex[10] = 2; cindex[11] = 3;
cindex[12] = 0; cindex[13] = 1; cindex[14] = 2; cindex[15] = 3;
cindex[16] = 0; cindex[17] = 1; cindex[18] = 2; cindex[19] = 3;
cindex[20] = 0; cindex[21] = 1; cindex[22] = 2; cindex[23] = 3;
pfGeoSet *gset = new pfGeoSet;
gset->setAttr(PFGS_COORD3, PFGS_PER_VERTEX, verts, vindex);
gset->setAttr(PFGS_COLOR4, PFGS_PER_VERTEX, colors, cindex);
gset->setPrimType(PFGS_QUADS);
gset->setNumPrims(6);
My changes, (Note: the index order is different from QUAD case)
pfVec3 *verts = (pfVec3*) new(8*sizeof(pfVec3)) pfMemory;
verts[0].set(-1.0f, -1.0f, 1.0f)
verts[1].set( 1.0f, -1.0f, 1.0f);
verts[2].set( 1.0f, 1.0f, 1.0f);
verts[3].set(-1.0f, 1.0f, 1.0f);
verts[4].set(-2.0f, -2.0f, 0.0f);
verts[5].set( 2.0f, -2.0f, 0.0f);
verts[6].set( 2.0f, 2.0f, 0.0f);
verts[7].set(-2.0f, 2.0f, 0.0f);
ushort *vindex = (ushort*) new(24*sizeof(ushort)) pfMemory;
vindex[0] = 0; vindex[1] = 1; vindex[2] = 3; vindex[3] = 2; // top
vindex[4] = 0; vindex[5] = 3; vindex[6] = 4; vindex[7] = 7; // left
vindex[8] = 4; vindex[9] = 7; vindex[10] = 5; vindex[11] = 6; //
bottom
vindex[12] = 1; vindex[13] = 5; vindex[14] = 2; vindex[15] = 6; //
right
vindex[16] = 3; vindex[17] = 2; vindex[18] = 7; vindex[19] = 6; // back
vindex[20] = 0; vindex[21] = 4; vindex[22] = 1; vindex[23] = 5; //
front
pfVec4 *colors = (pfVec4*) new(4*sizeof(pfVec4)) pfMemory;
colors[0].set(1.0f, 0.0f, 0.0f, 0.5f);
colors[1].set(0.0f, 1.0f, 0.0f, 0.5f);
colors[2].set(0.0f, 0.0f, 1.0f, 0.5f);
colors[3].set(1.0f, 1.0f, 1.0f, 0.5f);
ushort *cindex = (ushort*) new(24*sizeof(ushort)) pfMemory;
cindex[0] = 0; cindex[1] = 1; cindex[2] = 3; cindex[3] = 2;
cindex[4] = 0; cindex[5] = 1; cindex[6] = 3; cindex[7] = 2;
cindex[8] = 0; cindex[9] = 1; cindex[10] = 3; cindex[11] = 2;
cindex[12] = 0; cindex[13] = 1; cindex[14] = 3; cindex[15] = 2;
cindex[16] = 0; cindex[17] = 1; cindex[18] = 3; cindex[19] = 2;
cindex[20] = 0; cindex[21] = 1; cindex[22] = 3; cindex[23] = 2;
int *length = (int *) new(6*sizeof(int)) pfMemory;
for(uint i=0; i<6; i++)
length[i] = 4;
pfGeoSet *gset = new pfGeoSet;
gset->setPrimType(PFGS_TRISTRIPS);
gset->setPrimLengths(length);
gset->setAttr(PFGS_COORD3, PFGS_PER_VERTEX, verts, vindex);
gset->setAttr(PFGS_COLOR4, PFGS_PER_VERTEX, colors, cindex);
gset->setNumPrims(6);
After the change, please get the value of PFQHIT_PRIM, it always is 0. In
fact, in my application, it is always a constant value.
Thank you for your reconsideration.
Best regards
Yigang
Angus Dorbie wrote:
> You say you set a strip, a strip is a single primitive with several
> triangles. You may optionally have more than one triangle primitive and
> set the associated lengths array when you create the geoset so, to
> narrow everything down fully if you use multiple strips you need to look
> at PFQHIT_PRIM and PFQHIT_TRI, the former telling you which tristrip and
> the latter telling you which triangle in the strip. As things stand you
> probably only have the one primitive (and a single value in lengths)
> which is obviously always 0 and so PFQHIT_TRI will be the number you
> need indicating which triangle in strip 0 you have hit.
>
> Cheers,Angus.
>
> Yigang Wang wrote:
> >
> > Hi, all.
> >
> > I am making a program to select some parts of the triangle mesh with
> > Performer. I need the returned parameters of the index of strip
> > primitive (PFHIT_PRIM) and the index of triangle in the strip
> > (PFHIT_TRI). But it result in an error in my program. So i check the
> > example program /usr/share/Performer/src/pguide/libpf/C++/intersect.C
> >
> > I made a small change of the programe
> > /usr/share/Performer/src/pguide/libpf/C++/intersect.C, there appear an
> > strange result. In the example, i change the primitive of the pfGeoSet
> > (QUADS) to strips representation ( not change the real geometry), and
> > then i get the result of intersection from the fuuctions:
> > pfHit::query(&prim_index, PFHIT_PRIM) and pfHit::mQuery(&tri_index,
> > PFHIT_TRI), I found that the prim_index is always 0. However it
> > changed correctly for QUADS case or POLYS case.
> >
> > Is it a bug or not? Do i need to set more parameters for pfHit?
> >
> > Thanks for your reply.
> >
> > Yigang
> >
> >
> >
> >
> >
> >
> > --
> > **********************************************************************
> > Yigang Wang tel: +49 (2241) 14 2980
> > http://www.viswiz.gmd.de fax: +49 (2241) 14 2040
> > email: yigang.wang++at++gmd.de
> > GMD - The German National Research Center for Information Technology
> >
> >
>
> --
> For Performer+OpenGL tutorials http://www.dorbie.com/
>
> "In the middle of difficulty lies opportunity."
> --Albert Einstein
--
**********************************************************************
Yigang Wang tel: +49 (2241) 14 2980
http://www.viswiz.gmd.de fax: +49 (2241) 14 2040
email: yigang.wang++at++gmd.de
GMD - The German National Research Center for Information Technology
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