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// strips.cmd
// Creates strips as for OpenGL GL_TRIANGLE_STRIPS. Just colors the strips.
// But also see the graphics window 'S' and 'Y' commands.
// Programmer: Ken Brakke brakke@susqu.edu www.susqu.edu/brakke
// "strips" just takes one stab at a strip for each facet.
strips := {
local stripcolor,stripcount,testcolor;
local trystart,whichwaystart,whichway;
local eid,fid,fffid,eeid,goodstart,striplength;
local firstcount,secondcount,trucfacet;
set facet color white;
stripcolor := 1;
stripcount := 0;
foreach facet ff where color == white do
{ ff.color := stripcolor;
whichwaystart := 0;
while whichwaystart <= 1 do
{
eid := ff.edge[whichwaystart+1].oid;
fid := ff.id;
whichway := whichwaystart; // alternating directions of triangles
while edge[eid].valence >= 2 do
{
foreach edge[eid].facet fff do
{ if fff.id != fid then {fffid := fff.id; break;} };
if facet[fffid].color != white then break;
facet[fffid].color := stripcolor;
foreach facet[fffid].edge ee do
{ eeid := ee.oid;
if whichway then
{ if ee.vertex[2].id == edge[eid].vertex[2].id then break; }
else
{ if ee.vertex[1].id == edge[eid].vertex[1].id then break; }
};
eid := eeid;
fid := fffid;
whichway := !whichway;
};
whichwaystart += 1;
};
stripcolor := (stripcolor imod 14) + 1;
stripcount += 1;
};
printf "%g strips, average %g facets.\n",stripcount,facet_count/stripcount;
}
// "strips2" searches for longest strip through facet, out of 3 ways
strips2 := {
local stripcolor,stripcount,testcolor;
local trystart,whichwaystart,whichway;
local eid,fid,fffid,eeid,maxlength,goodstart,striplength;
set facet color white;
stripcolor := 1;
stripcount := 0;
testcolor := 100;
foreach facet ff where color == white do
{ ff.color := stripcolor;
// three-way trial first
trystart := 1; maxlength := 0; goodstart := 1;
while trystart <= 3 do
{ striplength := 1;
whichwaystart := 0;
while whichwaystart <= 1 do
{
eid := ff.edge[((whichwaystart+trystart)imod 3)+1].oid;
fid := ff.id;
whichway := whichwaystart; // alternating directions of triangles
while edge[eid].valence >= 2 do
{
foreach edge[eid].facet fff do
{ if fff.id != fid then {fffid := fff.id; break;} };
if facet[fffid].color != white then break;
facet[fffid].color := testcolor; striplength += 1;
foreach facet[fffid].edge ee do
{ eeid := ee.oid;
if whichway then
{ if ee.vertex[2].id == edge[eid].vertex[2].id then break; }
else
{ if ee.vertex[1].id == edge[eid].vertex[1].id then break; }
};
eid := eeid;
fid := fffid;
whichway := !whichway;
};
whichwaystart += 1;
};
if ( striplength > maxlength ) then
{ maxlength := striplength; goodstart := trystart; };
trystart += 1;
set facet color white where color==testcolor;
};
// now for real
whichwaystart := 0;
while whichwaystart <= 1 do
{
eid := ff.edge[((whichwaystart+goodstart)imod 3)+1].oid;
fid := ff.id;
whichway := whichwaystart; // alternating directions of triangles
while edge[eid].valence >= 2 do
{
foreach edge[eid].facet fff do
{ if fff.id != fid then {fffid := fff.id; break;} };
if facet[fffid].color != white then break;
facet[fffid].color := stripcolor;
foreach facet[fffid].edge ee do
{ eeid := ee.oid;
if whichway then
{ if ee.vertex[2].id == edge[eid].vertex[2].id then break; }
else
{ if ee.vertex[1].id == edge[eid].vertex[1].id then break; }
};
eid := eeid;
fid := fffid;
whichway := !whichway;
};
whichwaystart += 1;
};
stripcolor := (stripcolor imod 14) + 1;
stripcount += 1;
};
printf "%g strips, average %g facets.\n",stripcount,facet_count/stripcount;
}
// for testing whether order of trying facets matters much
define vertex attribute vertex_order_key real
define edge attribute edge_order_key real
define facet attribute facet_order_key real
define body attribute body_order_key real
define facetedge attribute facetedge_order_key real
reorder := {
set vertex vertex_order_key x+y+z;
set edge ee edge_order_key min(ee.vertex,vertex_order_key);
set facetedge fe facetedge_order_key fe.edge[1].edge_order_key;
set facet ff facet_order_key min(ff.vertex,vertex_order_key);
set body bb body_order_key min(bb.facet,facet_order_key);
reorder_storage;
}
// searches for longest strip through facet, out of 3 ways
// Uses same strip truncation as Evolver to get properly oriented strip.
strips3 := {
local fffid, eeid, maxlength, goodstart, striplength, testcolor, stripcolor;
local stripcount, trystart, whichwaystart, eid, fid, whichway, firstcount;
local secondcount, truncfacet;
testcolor := 100;
set facet color white;
stripcolor := 1;
stripcount := 0;
foreach facet ff where color == white do
{ ff.color := stripcolor;
// three-way trial first
trystart := 1; maxlength := 0; goodstart := 1;
while trystart <= 3 do
{ striplength := 1;
whichwaystart := 0;
while whichwaystart <= 1 do
{
eid := ff.edge[((whichwaystart+trystart)imod 3)+1].oid;
fid := ff.id;
whichway := whichwaystart; // alternating directions of triangles
while edge[eid].valence >= 2 do
{
firstcount := striplength;
foreach edge[eid].facet fff do
{ if fff.id != fid then {fffid := fff.id; break;} };
if facet[fffid].color != white then break;
facet[fffid].color := testcolor; striplength += 1;
foreach facet[fffid].edge ee do
{ eeid := ee.oid;
if whichway then
{ if ee.vertex[2].id == edge[eid].vertex[2].id then break; }
else
{ if ee.vertex[1].id == edge[eid].vertex[1].id then break; }
};
eid := eeid;
fid := fffid;
whichway := !whichway;
};
secondcount := striplength - firstcount;
whichwaystart += 1;
};
if ( (firstcount imod 2) and (secondcount imod 2) ) then striplength -= 1;
if ( striplength > maxlength ) then
{ maxlength := striplength; goodstart := trystart; };
trystart += 1;
set facet color white where color==testcolor;
};
// now for real
truncfacet := ff.id;
whichwaystart := 0;
while whichwaystart <= 1 do
{
firstcount := striplength;
eid := ff.edge[((whichwaystart+goodstart)imod 3)+1].oid;
fid := ff.id;
whichway := whichwaystart; // alternating directions of triangles
while edge[eid].valence >= 2 do
{
foreach edge[eid].facet fff do
{ if fff.id != fid then {fffid := fff.id; break;} };
if facet[fffid].color != white then break;
facet[fffid].color := stripcolor;
if ( whichwaystart == 1 ) then truncfacet := fffid;
foreach facet[fffid].edge ee do
{ eeid := ee.oid;
if whichway then
{ if ee.vertex[2].id == edge[eid].vertex[2].id then break; }
else
{ if ee.vertex[1].id == edge[eid].vertex[1].id then break; }
};
eid := eeid;
fid := fffid;
whichway := !whichway;
};
secondcount := striplength - firstcount;
whichwaystart += 1;
};
if ( (firstcount imod 2) and (secondcount imod 2) ) then
set facet[truncfacet] color white;
stripcolor := (stripcolor imod 14) + 1;
stripcount += 1;
};
printf "%g strips, average %g facets.\n",stripcount,facet_count/stripcount;
}
// end strips.cmd
/* Usage:
strips
strips2
*/
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