voxels-light.xtl

1⍝# Voxels, 14: light. The endless world, lit: a face open to the sky is
2⍝# in full sunlight; under an overhang, beneath a tree's crown or down a
3⍝# tunnel the light fades, a step a block, as it spreads from the open
4⍝# air. A lamp (the hotbar's eighth block) glows: its light spreads the
5⍝# same way through the air around it. N turns day to night and back --
6⍝# the sunlight and the sky go, the lamps stay -- by one number in scene,
7⍝# so nothing is worked out again. Each column's light is worked out as
8⍝# it is made (vx:c_olumnLight: sunlight by a scan down each column,
9⍝# then rounds of spreading), and again when an edit makes it again: dig
10⍝# a tunnel's roof open and the sun comes in.
11⍝# Run: just demo scene voxels-light
12⍝#   click (or X) dig, right-click (or E) place, 1 to 8 choose the block
13⍝#   (8 a lamp), N night or day, W A S D walk, Space jump, Shift run, F
14⍝#   fly, drag or the arrows to look, H back to the start, q quit
15
16ᵉⁿ⁼u̲se< "Endless"
17ᵖˡ⁼u̲se< "Play"
18ˢᶜ⁼u̲se< "Scene"
19
20w ← "Voxels 14: light -- X_eTaL" ˢᶜo̲pen! 640 400
21g ← w ˢᶜf̲og! 22.0 44.0
22k ← w ˢᶜs̲ky! 0.55 0.72 0.92
23k ← w ˢᶜc̲urve! 160.0
24
25ᵖˡhelpLit
26
27⍝## The light, checked
28
29⍝# Stone, 18 by 32 by 18 (a column with its border), with a shaft open to
30⍝# the sky at x 4, z 9 down to y 10, a tunnel at y 10 from it east to x
31⍝# 15, and a lamp at the tunnel's end (x 16). Along the tunnel the
32⍝# sunlight falls 3 a block from the shaft's 15; the lamplight falls 3 a
33⍝# block back from the lamp.
34ᵛˣ⁼u̲se< "Voxels"
35cell ← (r̲ange 18 × 32 × 18) − 1
36x ← cell d̲iv 32 × 18
37y ← (cell d̲iv 18) m̲od 32
38z ← cell m̲od 18
39shaft ← (x = 4) × (z = 9) × y ≥ 10
40tunnel ← (y = 10) × (z = 9) × (x ≥ 4) × x ≤ 15
41lamp ← (y = 10) × (z = 9) × x = 16
42b ← 18 32 18 r̲eshape (8 × lamp) + (1 − lamp) × 1 − 0 < shaft + tunnel
43ᵘs̲unOf ← { (sun, _) → sun }
44ᵘl̲ampOf ← { (_, lamp) → lamp }
45L ← ᵛˣc̲olumnLight b
46row ← 1 + tunnel r̲eplicate cell
47"sunlight along the tunnel, x 4 to 15:"
48row s̲elect r̲avel ᵘs̲unOf L
49"lamplight along it, the lamp at x 16:"
50row s̲elect r̲avel ᵘl̲ampOf L
51
52hud ← w ᵖˡh̲udLit 1
53s ← ᵉⁿl̲ighting ᵉⁿn̲ew w
54s ← (4 × (1 + 2 × ᵉⁿreach) × 1 + 2 × ᵉⁿreach) 'ᵉⁿs̲tream p̲ower s
55last ← 100000 'ᵖˡf̲rame p̲ower (s, 1)
56z ← ˢᶜc̲lose! w
57⍝ (an accessor, not a top-level tuple pattern: ask E10)
58ᵘw̲orldOf ← { (s, _) → s }
59s ← ᵘw̲orldOf last
60"by day (1) or night (2) at the end, and the lamps placed:"
61ᵉⁿl̲it s
62'+ r̲/ 8 = 4 s̲elect₂ ᵉⁿe̲dits s
63"bye"