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comparison semiconginev2/contrib/algorithms/texture_packing.nim @ 1226:c8e3037aca66 compiletime-tests

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add: contrib stuff
author sam <sam@basx.dev>
date Wed, 17 Jul 2024 23:41:51 +0700
parents
children 4e465583ea32
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1225:27cd1c21290e 1226:c8e3037aca66
1 type
2 Rect = tuple
3 i: int
4 x, y, w, h: uint32
5
6 func between(a1, a2, b: uint32): bool =
7 a1 <= b and b <= a2
8
9 func overlap(a1, a2, b1, b2: uint32): bool =
10 return between(a1, a2, b1) or
11 between(a1, a2, b2) or
12 between(b1, b2, a1) or
13 between(b1, b2, a2)
14
15 # FYI: also serves as "overlaps"
16 func advanceIfOverlap(fix, newRect: Rect): (bool, uint32) =
17 let overlapping = overlap(fix.x, fix.x + fix.w - 1, newRect.x, newRect.x + newRect.w - 1) and
18 overlap(fix.y, fix.y + fix.h - 1, newRect.y, newRect.y + newRect.h - 1)
19 if overlapping: (true, fix.x + fix.w) # next free x coordinate to the right
20 else: (false, newRect.x) # current position is fine
21
22 proc find_insertion_position(alreadyPlaced: seq[Rect], area: tuple[i: int, w, h: uint32], maxDim: uint32): (bool, Rect) =
23 var newRect = (i: area.i, x: 0'u32, y: 0'u32, w: area.w, h: area.h)
24
25 while newRect.y + newRect.h <= maxDim:
26 var hasOverlap = false
27 var advanceX: uint32
28
29 for placed in alreadyPlaced:
30 (hasOverlap, advanceX) = placed.advanceIfOverlap(newRect)
31 if hasOverlap: # rects were overlapping and newRect needs to be shifted to the right
32 newRect.x = advanceX
33 break
34
35 if not hasOverlap: # found a collision free position
36 return (true, newRect)
37
38 if newRect.x + newRect.w >= maxDim: # move to next scanline
39 newRect.x = 0
40 newRect.y += 1
41
42 return (false, newRect)
43
44
45 proc Pack*[T](textures: seq[Texture[T]]): tuple[atlas: Texture[T], coords: seq[tuple[x: uint32, y: uint32]]] =
46 const MAX_ATLAS_SIZE = 4096'u32
47 var areas: seq[tuple[i: int, w, h: uint32]]
48
49 for i in 0 ..< textures.len:
50 areas.add (i, textures[i].width, textures[i].height)
51
52 let areasBySize = areas.sortedByIt(-(it[1] * it[2]).int64)
53 var assignedAreas: seq[Rect]
54 var maxDim = 128'u32
55
56 for area in areasBySize:
57 var pos = find_insertion_position(assignedAreas, area, maxDim)
58 while not pos[0]: # this should actually never loop more than once, but weird things happen ¯\_(ツ)_/¯
59 maxDim = maxDim * 2
60 assert maxDim <= MAX_ATLAS_SIZE, &"Atlas gets bigger than {MAX_ATLAS_SIZE}, cannot pack textures"
61 pos = find_insertion_position(assignedAreas, area, maxDim)
62
63 assignedAreas.add pos[1]
64
65 # check there are overlaps
66 for i in 0 ..< assignedAreas.len - 1:
67 for j in i + 1 ..< assignedAreas.len:
68 assert not assignedAreas[i].advanceIfOverlap(assignedAreas[j])[0], &"{assignedAreas[i]} and {assignedAreas[j]} overlap!"
69
70 result.atlas = Texture[T](width: maxDim, height: maxDim, data: newSeq[T](maxDim * maxDim))
71 result.coords.setLen(textures.len)
72 for rect in assignedAreas:
73 for y in 0 ..< rect.h:
74 for x in 0 ..< rect.w:
75 assert result.atlas[rect.x + x, rect.y + y] == 0, "Atlas texture packing encountered an overlap error"
76 result.atlas[rect.x + x, rect.y + y] = textures[rect.i][x, y]
77 result.coords[rect.i] = (x: rect.x, y: rect.y)