voxels-faces.xtl

1⍝# Voxels, 2: which faces to draw. A face shows where a solid block's
2⍝# neighbor is not solid: six rotations of the solid mask, each compared
3⍝# with the mask itself (the idiom of Life), give every exposed face of
4⍝# the chunk at once; the faces become a list, one row each: x y z
5⍝# direction block. Checked on shapes with known answers, then the
6⍝# chunk's faces drawn as outlines in a 3D window, turning.
7⍝# Run: just demo scene voxels-faces   (drag to turn it; q or close: quit)
8
9ᵛˣ⁼u̲se< "Voxels"
10ˢᶜ⁼u̲se< "Scene"
11
12ones ← 16 16 16 r̲eshape 4096 r̲eshape 1
13inside ← 16 16 16 r̲eshape (ᵛˣxs > 0) × (ᵛˣxs < 15) × (ᵛˣys > 0) × (ᵛˣys < 15) × (ᵛˣzs > 0) × ᵛˣzs < 15
14one ← 16 16 16 r̲eshape (ᵛˣxs = 8) × (ᵛˣys = 8) × ᵛˣzs = 8
15checker ← 16 16 16 r̲eshape 0 = (ᵛˣxs + ᵛˣys + ᵛˣzs) m̲od 2
16"faces west east down up north south: one block, all solid, a hollow box, a 3D checkerboard:"
17ᵛˣc̲ount ᵛˣf̲aces one
18ᵛˣc̲ount ᵛˣf̲aces ones
19ᵛˣc̲ount ᵛˣf̲aces ones − inside
20ᵛˣc̲ount ᵛˣf̲aces checker
21
22b ← ᵛˣc̲hunk ᵛˣh̲ills 0.0
23f ← ᵛˣf̲aces b
24"the chunk: faces by direction, then all of them, then 6 per solid block if none were hidden:"
25ᵛˣc̲ount f
26t̲ally f
276 × '+ r̲/ r̲avel ᵛˣs̲olid b
28"the first faces (x y z direction block):"
294 t̲ake f
30
31w ← "Voxels 2: the faces -- X_eTaL" ˢᶜo̲pen! 560 560
32k ← w ˢᶜc̲amera! 0.7 0.5 3.4 0.35
33
34⍝# each kind of block as one object, in its color
35ᵘp̲ut ← { t →
36  sel ← (5 s̲elect₂ f) = t
37  0 = '+ r̲/ sel ? t + 1
38  head ← (f̲loat w c̲at t) c̲at (t + 1) s̲elect ᵛˣcolors
39  x ← head ˢᶜs̲egments! ᵛˣe̲dges sel r̲eplicate f
40  t + 1
41}
42put ← 7 'ᵘp̲ut p̲ower 1
43
44ᵘq̲uit ← { n →
45  z ← ˢᶜc̲lose! w
46  0
47}
48ᵘf̲rame ← { n →
49  n = 0 ? 0
50  v ← ˢᶜn̲ext! w
51  ((v m̲atch "close") + v m̲atch "key q") > 0 ? ᵘq̲uit n
52  n
53}
54last ← 100000 'ᵘf̲rame p̲ower 1
55"bye"