Edge Selection indices
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THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED
On 09/11/2012 at 01:32, xxxxxxxx wrote:
User Information:
Cinema 4D Version:
Platform: Windows ; Mac OSX ;
Language(s) : C++ ;---------
I have a question about what the edge index of a selection represents with respect to either a triangular or quadrangular polygon?"Edges are indexed (4*poly)+edge where edge is from 0-3."
If poly is a triangle and edge 2 is considered, is the edge from poly.c->poly.a or does it always represent poly.c->poly.a? Here is my code. Please help me validate that it is correctly considering the vertex indices represented by each edge:
LONG pi, ei; for (LONG seg = 0L; bs->GetRange(seg,&a,&b); ++seg) { for (i=a; i<=b; ++i) { pi = i/4L; ei = Mod(i,4L); if (ei == 0L) { DetermineAsSourceVertex(verts, normal, polys[pi].a, side, mepsilon); DetermineAsSourceVertex(verts, normal, polys[pi].b, side, mepsilon); } else if (ei == 1L) { DetermineAsSourceVertex(verts, normal, polys[pi].b, side, mepsilon); DetermineAsSourceVertex(verts, normal, polys[pi].c, side, mepsilon); } else if (ei == 2L) { DetermineAsSourceVertex(verts, normal, polys[pi].c, side, mepsilon); if (polys[pi].c != polys[pi].d) DetermineAsSourceVertex(verts, normal, polys[pi].d, side, mepsilon); else DetermineAsSourceVertex(verts, normal, polys[pi].a, side, mepsilon); } else // ei == 3L { DetermineAsSourceVertex(verts, normal, polys[pi].d, side, mepsilon); DetermineAsSourceVertex(verts, normal, polys[pi].a, side, mepsilon); } } } -
THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED
On 09/11/2012 at 03:55, xxxxxxxx wrote:
Yes, that looks right to me. I have made the same assumptions in my plugins.
/Filip
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THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED
On 20/11/2012 at 10:43, xxxxxxxx wrote:
I just woke up and haven't had me coffee yet but... are you sure that side 2 is used at all if it's a triangle? I may be crossing some info about one thing with another, but IIRC, side 2 is typically not used/indicated if it's a triangle, which would allow you to skip a test (not a big deal, either way).
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THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED
On 21/11/2012 at 05:45, xxxxxxxx wrote:
Edge 3 (for 0-3 indices) would be omitted and skipped for a triangle.
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THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED
On 21/11/2012 at 08:39, xxxxxxxx wrote:
My reference was from the PolyInfo structure, where you find this in the SDK docs...
`.... S N I P .... for (i=0; i<polygon_count; i++) { pli = n->GetPolyInfo(i); for (side=0; side<4; side++) // test all 4 sides of a polygon { // only proceed if edge has not already been processed // and edge really exists (***** for triangles side 2 from c..d does not exist as c==d ****** ) if (pli->mark[side] || side==2 && vadr[i].c==vadr[i].d) continue; // one can also skip the side==2 && vadr[i].c==vadr[i].d test as pli->mark[2] is always TRUE for triangles switch (side) { case 0: a=vadr[i].a; b=vadr[i].b; break; case 1: a=vadr[i].b; b=vadr[i].c; break; case 2: a=vadr[i].c; b=vadr[i].d; break; case 3: a=vadr[i].d; b=vadr[i].a; break; } // do something with the edge a..b } } ` 0-1-2-3 are the indices for a-b/b-c/c-d/d-a. For triangles the face/edge index 2 is set to NOTOK (as c == d). e.g. a value of 5-8-2-1 for 'face' means: a-b neighbor face is 5, b-c neighbor face is 8 etc. ` .... S N I P .... `...it seems to me that all references to edges (and/or edge numbering) would follow the same logic - since the c-d edge doesn't exist for triangles, it would/should not be listed/indicated.