summaryrefslogtreecommitdiffstats
path: root/external/include/stb_rect_pack.h
blob: c75527da1e082805aa994d347416277dfafa4f9c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
// stb_rect_pack.h - v0.10 - public domain - rectangle packing
// Sean Barrett 2014
//
// Useful for e.g. packing rectangular textures into an atlas.
// Does not do rotation.
//
// Not necessarily the awesomest packing method, but better than
// the totally naive one in stb_truetype (which is primarily what
// this is meant to replace).
//
// Has only had a few tests run, may have issues.
//
// More docs to come.
//
// No memory allocations; uses qsort() and assert() from stdlib.
// Can override those by defining STBRP_SORT and STBRP_ASSERT.
//
// This library currently uses the Skyline Bottom-Left algorithm.
//
// Please note: better rectangle packers are welcome! Please
// implement them to the same API, but with a different init
// function.
//
// Credits
//
//  Library
//    Sean Barrett
//  Minor features
//    Martins Mozeiko
//  Bugfixes / warning fixes
//    Jeremy Jaussaud
//
// Version history:
//
//     0.10  (2016-10-25)  remove cast-away-const to avoid warnings
//     0.09  (2016-08-27)  fix compiler warnings
//     0.08  (2015-09-13)  really fix bug with empty rects (w=0 or h=0)
//     0.07  (2015-09-13)  fix bug with empty rects (w=0 or h=0)
//     0.06  (2015-04-15)  added STBRP_SORT to allow replacing qsort
//     0.05:  added STBRP_ASSERT to allow replacing assert
//     0.04:  fixed minor bug in STBRP_LARGE_RECTS support
//     0.01:  initial release
//
// LICENSE
//
//   This software is dual-licensed to the public domain and under the following
//   license: you are granted a perpetual, irrevocable license to copy, modify,
//   publish, and distribute this file as you see fit.

//////////////////////////////////////////////////////////////////////////////
//
//       INCLUDE SECTION
//

#ifndef STB_INCLUDE_STB_RECT_PACK_H
#define STB_INCLUDE_STB_RECT_PACK_H

#define STB_RECT_PACK_VERSION  1

#ifdef STBRP_STATIC
#define STBRP_DEF static
#else
#define STBRP_DEF extern
#endif

#ifdef __cplusplus
extern "C" {
#endif

typedef struct stbrp_context stbrp_context;
typedef struct stbrp_node    stbrp_node;
typedef struct stbrp_rect    stbrp_rect;

#ifdef STBRP_LARGE_RECTS
typedef int            stbrp_coord;
#else
typedef unsigned short stbrp_coord;
#endif

STBRP_DEF void stbrp_pack_rects (stbrp_context *context, stbrp_rect *rects, int num_rects);
// Assign packed locations to rectangles. The rectangles are of type
// 'stbrp_rect' defined below, stored in the array 'rects', and there
// are 'num_rects' many of them.
//
// Rectangles which are successfully packed have the 'was_packed' flag
// set to a non-zero value and 'x' and 'y' store the minimum location
// on each axis (i.e. bottom-left in cartesian coordinates, top-left
// if you imagine y increasing downwards). Rectangles which do not fit
// have the 'was_packed' flag set to 0.
//
// You should not try to access the 'rects' array from another thread
// while this function is running, as the function temporarily reorders
// the array while it executes.
//
// To pack into another rectangle, you need to call stbrp_init_target
// again. To continue packing into the same rectangle, you can call
// this function again. Calling this multiple times with multiple rect
// arrays will probably produce worse packing results than calling it
// a single time with the full rectangle array, but the option is
// available.

struct stbrp_rect
{
   // reserved for your use:
   int            id;

   // input:
   stbrp_coord    w, h;

   // output:
   stbrp_coord    x, y;
   int            was_packed;  // non-zero if valid packing

}; // 16 bytes, nominally


STBRP_DEF void stbrp_init_target (stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes);
// Initialize a rectangle packer to:
//    pack a rectangle that is 'width' by 'height' in dimensions
//    using temporary storage provided by the array 'nodes', which is 'num_nodes' long
//
// You must call this function every time you start packing into a new target.
//
// There is no "shutdown" function. The 'nodes' memory must stay valid for
// the following stbrp_pack_rects() call (or calls), but can be freed after
// the call (or calls) finish.
//
// Note: to guarantee best results, either:
//       1. make sure 'num_nodes' >= 'width'
//   or  2. call stbrp_allow_out_of_mem() defined below with 'allow_out_of_mem = 1'
//
// If you don't do either of the above things, widths will be quantized to multiples
// of small integers to guarantee the algorithm doesn't run out of temporary storage.
//
// If you do #2, then the non-quantized algorithm will be used, but the algorithm
// may run out of temporary storage and be unable to pack some rectangles.

STBRP_DEF void stbrp_setup_allow_out_of_mem (stbrp_context *context, int allow_out_of_mem);
// Optionally call this function after init but before doing any packing to
// change the handling of the out-of-temp-memory scenario, described above.
// If you call init again, this will be reset to the default (false).


STBRP_DEF void stbrp_setup_heuristic (stbrp_context *context, int heuristic);
// Optionally select which packing heuristic the library should use. Different
// heuristics will produce better/worse results for different data sets.
// If you call init again, this will be reset to the default.

enum
{
   STBRP_HEURISTIC_Skyline_default=0,
   STBRP_HEURISTIC_Skyline_BL_sortHeight = STBRP_HEURISTIC_Skyline_default,
   STBRP_HEURISTIC_Skyline_BF_sortHeight
};


//////////////////////////////////////////////////////////////////////////////
//
// the details of the following structures don't matter to you, but they must
// be visible so you can handle the memory allocations for them

struct stbrp_node
{
   stbrp_coord  x,y;
   stbrp_node  *next;
};

struct stbrp_context
{
   int width;
   int height;
   int align;
   int init_mode;
   int heuristic;
   int num_nodes;
   stbrp_node *active_head;
   stbrp_node *free_head;
   stbrp_node extra[2]; // we allocate two extra nodes so optimal user-node-count is 'width' not 'width+2'
};

#ifdef __cplusplus
}
#endif

#endif

//////////////////////////////////////////////////////////////////////////////
//
//     IMPLEMENTATION SECTION
//

#ifdef STB_RECT_PACK_IMPLEMENTATION
#ifndef STBRP_SORT
#include <stdlib.h>
#define STBRP_SORT qsort
#endif

#ifndef STBRP_ASSERT
#include <assert.h>
#define STBRP_ASSERT assert
#endif

#ifdef _MSC_VER
#define STBRP__NOTUSED(v)  (void)(v)
#else
#define STBRP__NOTUSED(v)  (void)sizeof(v)
#endif

enum
{
   STBRP__INIT_skyline = 1
};

STBRP_DEF void stbrp_setup_heuristic(stbrp_context *context, int heuristic)
{
   switch (context->init_mode) {
      case STBRP__INIT_skyline:
         STBRP_ASSERT(heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight || heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight);
         context->heuristic = heuristic;
         break;
      default:
         STBRP_ASSERT(0);
   }
}

STBRP_DEF void stbrp_setup_allow_out_of_mem(stbrp_context *context, int allow_out_of_mem)
{
   if (allow_out_of_mem)
      // if it's ok to run out of memory, then don't bother aligning them;
      // this gives better packing, but may fail due to OOM (even though
      // the rectangles easily fit). @TODO a smarter approach would be to only
      // quantize once we've hit OOM, then we could get rid of this parameter.
      context->align = 1;
   else {
      // if it's not ok to run out of memory, then quantize the widths
      // so that num_nodes is always enough nodes.
      //
      // I.e. num_nodes * align >= width
      //                  align >= width / num_nodes
      //                  align = ceil(width/num_nodes)

      context->align = (context->width + context->num_nodes-1) / context->num_nodes;
   }
}

STBRP_DEF void stbrp_init_target(stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes)
{
   int i;
#ifndef STBRP_LARGE_RECTS
   STBRP_ASSERT(width <= 0xffff && height <= 0xffff);
#endif

   for (i=0; i < num_nodes-1; ++i)
      nodes[i].next = &nodes[i+1];
   nodes[i].next = NULL;
   context->init_mode = STBRP__INIT_skyline;
   context->heuristic = STBRP_HEURISTIC_Skyline_default;
   context->free_head = &nodes[0];
   context->active_head = &context->extra[0];
   context->width = width;
   context->height = height;
   context->num_nodes = num_nodes;
   stbrp_setup_allow_out_of_mem(context, 0);

   // node 0 is the full width, node 1 is the sentinel (lets us not store width explicitly)
   context->extra[0].x = 0;
   context->extra[0].y = 0;
   context->extra[0].next = &context->extra[1];
   context->extra[1].x = (stbrp_coord) width;
#ifdef STBRP_LARGE_RECTS
   context->extra[1].y = (1<<30);
#else
   context->extra[1].y = 65535;
#endif
   context->extra[1].next = NULL;
}

// find minimum y position if it starts at x1
static int stbrp__skyline_find_min_y(stbrp_context *c, stbrp_node *first, int x0, int width, int *pwaste)
{
   stbrp_node *node = first;
   int x1 = x0 + width;
   int min_y, visited_width, waste_area;

   STBRP__NOTUSED(c);

   STBRP_ASSERT(first->x <= x0);

   #if 0
   // skip in case we're past the node
   while (node->next->x <= x0)
      ++node;
   #else
   STBRP_ASSERT(node->next->x > x0); // we ended up handling this in the caller for efficiency
   #endif

   STBRP_ASSERT(node->x <= x0);

   min_y = 0;
   waste_area = 0;
   visited_width = 0;
   while (node->x < x1) {
      if (node->y > min_y) {
         // raise min_y higher.
         // we've accounted for all waste up to min_y,
         // but we'll now add more waste for everything we've visted
         waste_area += visited_width * (node->y - min_y);
         min_y = node->y;
         // the first time through, visited_width might be reduced
         if (node->x < x0)
            visited_width += node->next->x - x0;
         else
            visited_width += node->next->x - node->x;
      } else {
         // add waste area
         int under_width = node->next->x - node->x;
         if (under_width + visited_width > width)
            under_width = width - visited_width;
         waste_area += under_width * (min_y - node->y);
         visited_width += under_width;
      }
      node = node->next;
   }

   *pwaste = waste_area;
   return min_y;
}

typedef struct
{
   int x,y;
   stbrp_node **prev_link;
} stbrp__findresult;

static stbrp__findresult stbrp__skyline_find_best_pos(stbrp_context *c, int width, int height)
{
   int best_waste = (1<<30), best_x, best_y = (1 << 30);
   stbrp__findresult fr;
   stbrp_node **prev, *node, *tail, **best = NULL;

   // align to multiple of c->align
   width = (width + c->align - 1);
   width -= width % c->align;
   STBRP_ASSERT(width % c->align == 0);

   node = c->active_head;
   prev = &c->active_head;
   while (node->x + width <= c->width) {
      int y,waste;
      y = stbrp__skyline_find_min_y(c, node, node->x, width, &waste);
      if (c->heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight) { // actually just want to test BL
         // bottom left
         if (y < best_y) {
            best_y = y;
            best = prev;
         }
      } else {
         // best-fit
         if (y + height <= c->height) {
            // can only use it if it first vertically
            if (y < best_y || (y == best_y && waste < best_waste)) {
               best_y = y;
               best_waste = waste;
               best = prev;
            }
         }
      }
      prev = &node->next;
      node = node->next;
   }

   best_x = (best == NULL) ? 0 : (*best)->x;

   // if doing best-fit (BF), we also have to try aligning right edge to each node position
   //
   // e.g, if fitting
   //
   //     ____________________
   //    |____________________|
   //
   //            into
   //
   //   |                         |
   //   |             ____________|
   //   |____________|
   //
   // then right-aligned reduces waste, but bottom-left BL is always chooses left-aligned
   //
   // This makes BF take about 2x the time

   if (c->heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight) {
      tail = c->active_head;
      node = c->active_head;
      prev = &c->active_head;
      // find first node that's admissible
      while (tail->x < width)
         tail = tail->next;
      while (tail) {
         int xpos = tail->x - width;
         int y,waste;
         STBRP_ASSERT(xpos >= 0);
         // find the left position that matches this
         while (node->next->x <= xpos) {
            prev = &node->next;
            node = node->next;
         }
         STBRP_ASSERT(node->next->x > xpos && node->x <= xpos);
         y = stbrp__skyline_find_min_y(c, node, xpos, width, &waste);
         if (y + height < c->height) {
            if (y <= best_y) {
               if (y < best_y || waste < best_waste || (waste==best_waste && xpos < best_x)) {
                  best_x = xpos;
                  STBRP_ASSERT(y <= best_y);
                  best_y = y;
                  best_waste = waste;
                  best = prev;
               }
            }
         }
         tail = tail->next;
      }         
   }

   fr.prev_link = best;
   fr.x = best_x;
   fr.y = best_y;
   return fr;
}

static stbrp__findresult stbrp__skyline_pack_rectangle(stbrp_context *context, int width, int height)
{
   // find best position according to heuristic
   stbrp__findresult res = stbrp__skyline_find_best_pos(context, width, height);
   stbrp_node *node, *cur;

   // bail if:
   //    1. it failed
   //    2. the best node doesn't fit (we don't always check this)
   //    3. we're out of memory
   if (res.prev_link == NULL || res.y + height > context->height || context->free_head == NULL) {
      res.prev_link = NULL;
      return res;
   }

   // on success, create new node
   node = context->free_head;
   node->x = (stbrp_coord) res.x;
   node->y = (stbrp_coord) (res.y + height);

   context->free_head = node->next;

   // insert the new node into the right starting point, and
   // let 'cur' point to the remaining nodes needing to be
   // stiched back in

   cur = *res.prev_link;
   if (cur->x < res.x) {
      // preserve the existing one, so start testing with the next one
      stbrp_node *next = cur->next;
      cur->next = node;
      cur = next;
   } else {
      *res.prev_link = node;
   }

   // from here, traverse cur and free the nodes, until we get to one
   // that shouldn't be freed
   while (cur->next && cur->next->x <= res.x + width) {
      stbrp_node *next = cur->next;
      // move the current node to the free list
      cur->next = context->free_head;
      context->free_head = cur;
      cur = next;
   }

   // stitch the list back in
   node->next = cur;

   if (cur->x < res.x + width)
      cur->x = (stbrp_coord) (res.x + width);

#ifdef _DEBUG
   cur = context->active_head;
   while (cur->x < context->width) {
      STBRP_ASSERT(cur->x < cur->next->x);
      cur = cur->next;
   }
   STBRP_ASSERT(cur->next == NULL);

   {
      stbrp_node *L1 = NULL, *L2 = NULL;
      int count=0;
      cur = context->active_head;
      while (cur) {
         L1 = cur;
         cur = cur->next;
         ++count;
      }
      cur = context->free_head;
      while (cur) {
         L2 = cur;
         cur = cur->next;
         ++count;
      }
      STBRP_ASSERT(count == context->num_nodes+2);
   }
#endif

   return res;
}

static int rect_height_compare(const void *a, const void *b)
{
   const stbrp_rect *p = (const stbrp_rect *) a;
   const stbrp_rect *q = (const stbrp_rect *) b;
   if (p->h > q->h)
      return -1;
   if (p->h < q->h)
      return  1;
   return (p->w > q->w) ? -1 : (p->w < q->w);
}

static int rect_width_compare(const void *a, const void *b)
{
   const stbrp_rect *p = (const stbrp_rect *) a;
   const stbrp_rect *q = (const stbrp_rect *) b;
   if (p->w > q->w)
      return -1;
   if (p->w < q->w)
      return  1;
   return (p->h > q->h) ? -1 : (p->h < q->h);
}

static int rect_original_order(const void *a, const void *b)
{
   const stbrp_rect *p = (const stbrp_rect *) a;
   const stbrp_rect *q = (const stbrp_rect *) b;
   return (p->was_packed < q->was_packed) ? -1 : (p->was_packed > q->was_packed);
}

#ifdef STBRP_LARGE_RECTS
#define STBRP__MAXVAL  0xffffffff
#else
#define STBRP__MAXVAL  0xffff
#endif

STBRP_DEF void stbrp_pack_rects(stbrp_context *context, stbrp_rect *rects, int num_rects)
{
   int i;

   // we use the 'was_packed' field internally to allow sorting/unsorting
   for (i=0; i < num_rects; ++i) {
      rects[i].was_packed = i;
      #ifndef STBRP_LARGE_RECTS
      STBRP_ASSERT(rects[i].w <= 0xffff && rects[i].h <= 0xffff);
      #endif
   }

   // sort according to heuristic
   STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_height_compare);

   for (i=0; i < num_rects; ++i) {
      if (rects[i].w == 0 || rects[i].h == 0) {
         rects[i].x = rects[i].y = 0;  // empty rect needs no space
      } else {
         stbrp__findresult fr = stbrp__skyline_pack_rectangle(context, rects[i].w, rects[i].h);
         if (fr.prev_link) {
            rects[i].x = (stbrp_coord) fr.x;
            rects[i].y = (stbrp_coord) fr.y;
         } else {
            rects[i].x = rects[i].y = STBRP__MAXVAL;
         }
      }
   }

   // unsort
   STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_original_order);

   // set was_packed flags
   for (i=0; i < num_rects; ++i)
      rects[i].was_packed = !(rects[i].x == STBRP__MAXVAL && rects[i].y == STBRP__MAXVAL);
}
#endif