Dragon rib arch

1asset dragon_rib "Dragon rib arch" complexity=6 float
2// one rib-pair of the ancient dragon the crypt was carved into: two colossal ivory ribs bow out from
3// rubble mounds either side of the hall and meet overhead under a chunky vertebra with a tall spine
4// fin. The feet sink 0.4 m below the origin (the scene places it with lift=0.4 so it stands clear of
5// the floor clutter under it). Seeds hang a candle wheel, an iron cage or moss from the vertebra.
6let H = 8.6..9.2
7let W = 8.4
8let boneC = cream:3|birch:2|sandstone
9let oldC = boneC*.82
10let rubbleC = rockGrey:2|rockCool|greystone
11let mossC = moss:2|leafD
12let hang = int(0..2)
13 
14// the two ribs: fat at the spine, thinner at the foot, bowing out then in
15tube rib mirror pts=[W-.25, -.4, 1.0  W+.3, 1.5, .8  W+.5, 3.4, .5  W+.15, 5.3, .25  W*.8, 6.9, .1  W*.5, 8.1, 0  W*.2, H-.05, 0  .6, H+.1, 0] r=(.3, .72) smooth sides=14 color=boneC
16ball knuckle on=rib at=(W*.12, H, 0) r=(.62, .55, .6) color=boneC segs=14 rings=9
17ball kneeB on=rib at=(W+.42, 2.4, .65) r=(.5, .62, .5) color=boneC segs=14 rings=9
18ball chip x3 on=rib at=(W+.32, 4.6, .35) chain=(-.55, .8, 0) r=(.36, .2, .4) color=oldC segs=10 rings=6
19 
20// rubble the feet are planted in
21puff mound on=rib at=(W-.2, -.25, .95) r=(1.1, .5, .95) color=rubbleC under=rubbleC*.8 segs=14 rings=8
22puff stone on=mound at=(.7, .15, .5) r=(.45, .32, .4) color=rubbleC*.9 segs=10 rings=6
23puff stoneB on=mound at=(-.6, .1, -.55) r=(.4, .3, .38) color=rubbleC*1.08 segs=10 rings=6
24puff stoneC on=mound at=(-.2, .05, .8) r=(.3, .22, .28) color=rubbleC*.96 segs=8 rings=5
25ball skullR on=mound at=(.2, .4, .65) r=(.2, .17, .2) color=boneC segs=10 rings=7 if=hang==1
26 
27// the vertebra on top: body, spine fin, side wings and discs fore and aft
28box vert at=(0, H-.75, 0) size=(1.5, 1.45, 2.3) round=.42 bands=[.2:boneC .8:oldC] color=boneC
29cone fin on=vert at=(0, 1.2, -.2) rot=(-12, 0, 0) h=1.9 r=.55 r2=.12 depth=.45 color=boneC segs=12
30ball finTip on=fin at=(0, 1.9, 0) r=(.16, .2, .12) color=boneC segs=8 rings=5
31cone wing on=vert at=(.6, .8, 0) mirror rot=(0, 0, -100) h=1.1 r=.36 r2=.14 depth=.6 color=boneC segs=10
32cyl disc x2 on=vert at=(0, .72, -.07) row=(0, 0, 2.36) rot=(90, 0, 0) h=.14 r=.6 color=oldC segs=16
33 
34// hangings, by seed: a candle wheel, a hanging cage, or moss drapes
35rod chain on=vert at=(0, .1, .6) to=(0, -2.4, 0) r=.045 sides=5 color=iron if=hang<2
36torus wheel on=chain at=end R=.7 r=.07 color=iron segs=20 sides=6 if=hang==0
37cyl candle x5 on=wheel ring at=(.7, .05, 0) h=.26 r=.06 color=cream segs=6
38ball flame on=candle at=(0, .34, 0) r=(.05, .09, .05) color=glow ink=glow segs=6 rings=4 joint
39cyl cage on=chain at=end+(0, -1.38, 0) h=1.3 r=.48 color=iron stripes=[iron inkDark] panels=8 scallop=.03 open=both segs=8 if=hang==1
40cone cageTop on=cage at=(0, 1.3, 0) h=.32 r=.52 color=iron segs=8
41cyl cageFloor on=cage at=(0, -.05, 0) h=.08 r=.5 color=iron segs=8
42ball skullC on=cage at=(0, .32, 0) r=(.2, .18, .2) color=boneC segs=10 rings=7
43puff drape x3 on=rib row=(0, -1.6, 0) at=(W+.45, 4.3, .45) r=(.3, .5, .32) color=mossC segs=8 rings=5 if=hang==2
44 
45anim flame s sin amp=.25 hz=2.6 stagger=.2
46