1// stb_rect_pack.h - v1.01 - public domain - rectangle packing
2// Sean Barrett 2014
3//
4// Useful for e.g. packing rectangular textures into an atlas.
5// Does not do rotation.
6//
7// Before #including,
8//
9// #define STB_RECT_PACK_IMPLEMENTATION
10//
11// in the file that you want to have the implementation.
12//
13// Not necessarily the awesomest packing method, but better than
14// the totally naive one in stb_truetype (which is primarily what
15// this is meant to replace).
16//
17// Has only had a few tests run, may have issues.
18//
19// More docs to come.
20//
21// No memory allocations; uses qsort() and assert() from stdlib.
22// Can override those by defining STBRP_SORT and STBRP_ASSERT.
23//
24// This library currently uses the Skyline Bottom-Left algorithm.
25//
26// Please note: better rectangle packers are welcome! Please
27// implement them to the same API, but with a different init
28// function.
29//
30// Credits
31//
32// Library
33// Sean Barrett
34// Minor features
35// Martins Mozeiko
36// github:IntellectualKitty
37//
38// Bugfixes / warning fixes
39// Jeremy Jaussaud
40// Fabian Giesen
41//
42// Version history:
43//
44// 1.01 (2021-07-11) always use large rect mode, expose STBRP__MAXVAL in public section
45// 1.00 (2019-02-25) avoid small space waste; gracefully fail too-wide rectangles
46// 0.99 (2019-02-07) warning fixes
47// 0.11 (2017-03-03) return packing success/fail result
48// 0.10 (2016-10-25) remove cast-away-const to avoid warnings
49// 0.09 (2016-08-27) fix compiler warnings
50// 0.08 (2015-09-13) really fix bug with empty rects (w=0 or h=0)
51// 0.07 (2015-09-13) fix bug with empty rects (w=0 or h=0)
52// 0.06 (2015-04-15) added STBRP_SORT to allow replacing qsort
53// 0.05: added STBRP_ASSERT to allow replacing assert
54// 0.04: fixed minor bug in STBRP_LARGE_RECTS support
55// 0.01: initial release
56//
57// LICENSE
58//
59// See end of file for license information.
60
61//////////////////////////////////////////////////////////////////////////////
62//
63// INCLUDE SECTION
64//
65
66#ifndef STB_INCLUDE_STB_RECT_PACK_H
67#define STB_INCLUDE_STB_RECT_PACK_H
68
69#define STB_RECT_PACK_VERSION 1
70
71#ifdef STBRP_STATIC
72#define STBRP_DEF static
73#else
74#define STBRP_DEF extern
75#endif
76
77#ifdef __cplusplus
78extern "C" {
79#endif
80
81typedef struct stbrp_context stbrp_context;
82typedef struct stbrp_node stbrp_node;
83typedef struct stbrp_rect stbrp_rect;
84
85typedef int stbrp_coord;
86
87#define STBRP__MAXVAL 0x7fffffff
88// Mostly for internal use, but this is the maximum supported coordinate value.
89
90STBRP_DEF int stbrp_pack_rects (stbrp_context *context, stbrp_rect *rects, int num_rects);
91// Assign packed locations to rectangles. The rectangles are of type
92// 'stbrp_rect' defined below, stored in the array 'rects', and there
93// are 'num_rects' many of them.
94//
95// Rectangles which are successfully packed have the 'was_packed' flag
96// set to a non-zero value and 'x' and 'y' store the minimum location
97// on each axis (i.e. bottom-left in cartesian coordinates, top-left
98// if you imagine y increasing downwards). Rectangles which do not fit
99// have the 'was_packed' flag set to 0.
100//
101// You should not try to access the 'rects' array from another thread
102// while this function is running, as the function temporarily reorders
103// the array while it executes.
104//
105// To pack into another rectangle, you need to call stbrp_init_target
106// again. To continue packing into the same rectangle, you can call
107// this function again. Calling this multiple times with multiple rect
108// arrays will probably produce worse packing results than calling it
109// a single time with the full rectangle array, but the option is
110// available.
111//
112// The function returns 1 if all of the rectangles were successfully
113// packed and 0 otherwise.
114
115struct stbrp_rect
116{
117 // reserved for your use:
118 int id;
119
120 // input:
121 stbrp_coord w, h;
122
123 // output:
124 stbrp_coord x, y;
125 int was_packed; // non-zero if valid packing
126
127}; // 16 bytes, nominally
128
129
130STBRP_DEF void stbrp_init_target (stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes);
131// Initialize a rectangle packer to:
132// pack a rectangle that is 'width' by 'height' in dimensions
133// using temporary storage provided by the array 'nodes', which is 'num_nodes' long
134//
135// You must call this function every time you start packing into a new target.
136//
137// There is no "shutdown" function. The 'nodes' memory must stay valid for
138// the following stbrp_pack_rects() call (or calls), but can be freed after
139// the call (or calls) finish.
140//
141// Note: to guarantee best results, either:
142// 1. make sure 'num_nodes' >= 'width'
143// or 2. call stbrp_allow_out_of_mem() defined below with 'allow_out_of_mem = 1'
144//
145// If you don't do either of the above things, widths will be quantized to multiples
146// of small integers to guarantee the algorithm doesn't run out of temporary storage.
147//
148// If you do #2, then the non-quantized algorithm will be used, but the algorithm
149// may run out of temporary storage and be unable to pack some rectangles.
150
151STBRP_DEF void stbrp_setup_allow_out_of_mem (stbrp_context *context, int allow_out_of_mem);
152// Optionally call this function after init but before doing any packing to
153// change the handling of the out-of-temp-memory scenario, described above.
154// If you call init again, this will be reset to the default (false).
155
156
157STBRP_DEF void stbrp_setup_heuristic (stbrp_context *context, int heuristic);
158// Optionally select which packing heuristic the library should use. Different
159// heuristics will produce better/worse results for different data sets.
160// If you call init again, this will be reset to the default.
161
162enum
163{
164 STBRP_HEURISTIC_Skyline_default=0,
165 STBRP_HEURISTIC_Skyline_BL_sortHeight = STBRP_HEURISTIC_Skyline_default,
166 STBRP_HEURISTIC_Skyline_BF_sortHeight
167};
168
169
170//////////////////////////////////////////////////////////////////////////////
171//
172// the details of the following structures don't matter to you, but they must
173// be visible so you can handle the memory allocations for them
174
175struct stbrp_node
176{
177 stbrp_coord x,y;
178 stbrp_node *next;
179};
180
181struct stbrp_context
182{
183 int width;
184 int height;
185 int align;
186 int init_mode;
187 int heuristic;
188 int num_nodes;
189 stbrp_node *active_head;
190 stbrp_node *free_head;
191 stbrp_node extra[2]; // we allocate two extra nodes so optimal user-node-count is 'width' not 'width+2'
192};
193
194#ifdef __cplusplus
195}
196#endif
197
198#endif
199
200//////////////////////////////////////////////////////////////////////////////
201//
202// IMPLEMENTATION SECTION
203//
204
205#ifdef STB_RECT_PACK_IMPLEMENTATION
206#ifndef STBRP_SORT
207#include <stdlib.h>
208#define STBRP_SORT qsort
209#endif
210
211#ifndef STBRP_ASSERT
212#include <assert.h>
213#define STBRP_ASSERT assert
214#endif
215
216#ifdef _MSC_VER
217#define STBRP__NOTUSED(v) (void)(v)
218#define STBRP__CDECL __cdecl
219#else
220#define STBRP__NOTUSED(v) (void)sizeof(v)
221#define STBRP__CDECL
222#endif
223
224enum
225{
226 STBRP__INIT_skyline = 1
227};
228
229STBRP_DEF void stbrp_setup_heuristic(stbrp_context *context, int heuristic)
230{
231 switch (context->init_mode) {
232 case STBRP__INIT_skyline:
233 STBRP_ASSERT(heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight || heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight);
234 context->heuristic = heuristic;
235 break;
236 default:
237 STBRP_ASSERT(0);
238 }
239}
240
241STBRP_DEF void stbrp_setup_allow_out_of_mem(stbrp_context *context, int allow_out_of_mem)
242{
243 if (allow_out_of_mem)
244 // if it's ok to run out of memory, then don't bother aligning them;
245 // this gives better packing, but may fail due to OOM (even though
246 // the rectangles easily fit). @TODO a smarter approach would be to only
247 // quantize once we've hit OOM, then we could get rid of this parameter.
248 context->align = 1;
249 else {
250 // if it's not ok to run out of memory, then quantize the widths
251 // so that num_nodes is always enough nodes.
252 //
253 // I.e. num_nodes * align >= width
254 // align >= width / num_nodes
255 // align = ceil(width/num_nodes)
256
257 context->align = (context->width + context->num_nodes-1) / context->num_nodes;
258 }
259}
260
261STBRP_DEF void stbrp_init_target(stbrp_context *context, int width, int height, stbrp_node *nodes, int num_nodes)
262{
263 int i;
264
265 for (i=0; i < num_nodes-1; ++i)
266 nodes[i].next = &nodes[i+1];
267 nodes[i].next = NULL;
268 context->init_mode = STBRP__INIT_skyline;
269 context->heuristic = STBRP_HEURISTIC_Skyline_default;
270 context->free_head = &nodes[0];
271 context->active_head = &context->extra[0];
272 context->width = width;
273 context->height = height;
274 context->num_nodes = num_nodes;
275 stbrp_setup_allow_out_of_mem(context, 0);
276
277 // node 0 is the full width, node 1 is the sentinel (lets us not store width explicitly)
278 context->extra[0].x = 0;
279 context->extra[0].y = 0;
280 context->extra[0].next = &context->extra[1];
281 context->extra[1].x = (stbrp_coord) width;
282 context->extra[1].y = (1<<30);
283 context->extra[1].next = NULL;
284}
285
286// find minimum y position if it starts at x1
287static int stbrp__skyline_find_min_y(stbrp_context *c, stbrp_node *first, int x0, int width, int *pwaste)
288{
289 stbrp_node *node = first;
290 int x1 = x0 + width;
291 int min_y, visited_width, waste_area;
292
293 STBRP__NOTUSED(c);
294
295 STBRP_ASSERT(first->x <= x0);
296
297 #if 0
298 // skip in case we're past the node
299 while (node->next->x <= x0)
300 ++node;
301 #else
302 STBRP_ASSERT(node->next->x > x0); // we ended up handling this in the caller for efficiency
303 #endif
304
305 STBRP_ASSERT(node->x <= x0);
306
307 min_y = 0;
308 waste_area = 0;
309 visited_width = 0;
310 while (node->x < x1) {
311 if (node->y > min_y) {
312 // raise min_y higher.
313 // we've accounted for all waste up to min_y,
314 // but we'll now add more waste for everything we've visted
315 waste_area += visited_width * (node->y - min_y);
316 min_y = node->y;
317 // the first time through, visited_width might be reduced
318 if (node->x < x0)
319 visited_width += node->next->x - x0;
320 else
321 visited_width += node->next->x - node->x;
322 } else {
323 // add waste area
324 int under_width = node->next->x - node->x;
325 if (under_width + visited_width > width)
326 under_width = width - visited_width;
327 waste_area += under_width * (min_y - node->y);
328 visited_width += under_width;
329 }
330 node = node->next;
331 }
332
333 *pwaste = waste_area;
334 return min_y;
335}
336
337typedef struct
338{
339 int x,y;
340 stbrp_node **prev_link;
341} stbrp__findresult;
342
343static stbrp__findresult stbrp__skyline_find_best_pos(stbrp_context *c, int width, int height)
344{
345 int best_waste = (1<<30), best_x, best_y = (1 << 30);
346 stbrp__findresult fr;
347 stbrp_node **prev, *node, *tail, **best = NULL;
348
349 // align to multiple of c->align
350 width = (width + c->align - 1);
351 width -= width % c->align;
352 STBRP_ASSERT(width % c->align == 0);
353
354 // if it can't possibly fit, bail immediately
355 if (width > c->width || height > c->height) {
356 fr.prev_link = NULL;
357 fr.x = fr.y = 0;
358 return fr;
359 }
360
361 node = c->active_head;
362 prev = &c->active_head;
363 while (node->x + width <= c->width) {
364 int y,waste;
365 y = stbrp__skyline_find_min_y(c, node, node->x, width, &waste);
366 if (c->heuristic == STBRP_HEURISTIC_Skyline_BL_sortHeight) { // actually just want to test BL
367 // bottom left
368 if (y < best_y) {
369 best_y = y;
370 best = prev;
371 }
372 } else {
373 // best-fit
374 if (y + height <= c->height) {
375 // can only use it if it first vertically
376 if (y < best_y || (y == best_y && waste < best_waste)) {
377 best_y = y;
378 best_waste = waste;
379 best = prev;
380 }
381 }
382 }
383 prev = &node->next;
384 node = node->next;
385 }
386
387 best_x = (best == NULL) ? 0 : (*best)->x;
388
389 // if doing best-fit (BF), we also have to try aligning right edge to each node position
390 //
391 // e.g, if fitting
392 //
393 // ____________________
394 // |____________________|
395 //
396 // into
397 //
398 // | |
399 // | ____________|
400 // |____________|
401 //
402 // then right-aligned reduces waste, but bottom-left BL is always chooses left-aligned
403 //
404 // This makes BF take about 2x the time
405
406 if (c->heuristic == STBRP_HEURISTIC_Skyline_BF_sortHeight) {
407 tail = c->active_head;
408 node = c->active_head;
409 prev = &c->active_head;
410 // find first node that's admissible
411 while (tail->x < width)
412 tail = tail->next;
413 while (tail) {
414 int xpos = tail->x - width;
415 int y,waste;
416 STBRP_ASSERT(xpos >= 0);
417 // find the left position that matches this
418 while (node->next->x <= xpos) {
419 prev = &node->next;
420 node = node->next;
421 }
422 STBRP_ASSERT(node->next->x > xpos && node->x <= xpos);
423 y = stbrp__skyline_find_min_y(c, node, xpos, width, &waste);
424 if (y + height <= c->height) {
425 if (y <= best_y) {
426 if (y < best_y || waste < best_waste || (waste==best_waste && xpos < best_x)) {
427 best_x = xpos;
428 STBRP_ASSERT(y <= best_y);
429 best_y = y;
430 best_waste = waste;
431 best = prev;
432 }
433 }
434 }
435 tail = tail->next;
436 }
437 }
438
439 fr.prev_link = best;
440 fr.x = best_x;
441 fr.y = best_y;
442 return fr;
443}
444
445static stbrp__findresult stbrp__skyline_pack_rectangle(stbrp_context *context, int width, int height)
446{
447 // find best position according to heuristic
448 stbrp__findresult res = stbrp__skyline_find_best_pos(context, width, height);
449 stbrp_node *node, *cur;
450
451 // bail if:
452 // 1. it failed
453 // 2. the best node doesn't fit (we don't always check this)
454 // 3. we're out of memory
455 if (res.prev_link == NULL || res.y + height > context->height || context->free_head == NULL) {
456 res.prev_link = NULL;
457 return res;
458 }
459
460 // on success, create new node
461 node = context->free_head;
462 node->x = (stbrp_coord) res.x;
463 node->y = (stbrp_coord) (res.y + height);
464
465 context->free_head = node->next;
466
467 // insert the new node into the right starting point, and
468 // let 'cur' point to the remaining nodes needing to be
469 // stiched back in
470
471 cur = *res.prev_link;
472 if (cur->x < res.x) {
473 // preserve the existing one, so start testing with the next one
474 stbrp_node *next = cur->next;
475 cur->next = node;
476 cur = next;
477 } else {
478 *res.prev_link = node;
479 }
480
481 // from here, traverse cur and free the nodes, until we get to one
482 // that shouldn't be freed
483 while (cur->next && cur->next->x <= res.x + width) {
484 stbrp_node *next = cur->next;
485 // move the current node to the free list
486 cur->next = context->free_head;
487 context->free_head = cur;
488 cur = next;
489 }
490
491 // stitch the list back in
492 node->next = cur;
493
494 if (cur->x < res.x + width)
495 cur->x = (stbrp_coord) (res.x + width);
496
497#ifdef _DEBUG
498 cur = context->active_head;
499 while (cur->x < context->width) {
500 STBRP_ASSERT(cur->x < cur->next->x);
501 cur = cur->next;
502 }
503 STBRP_ASSERT(cur->next == NULL);
504
505 {
506 int count=0;
507 cur = context->active_head;
508 while (cur) {
509 cur = cur->next;
510 ++count;
511 }
512 cur = context->free_head;
513 while (cur) {
514 cur = cur->next;
515 ++count;
516 }
517 STBRP_ASSERT(count == context->num_nodes+2);
518 }
519#endif
520
521 return res;
522}
523
524static int STBRP__CDECL rect_height_compare(const void *a, const void *b)
525{
526 const stbrp_rect *p = (const stbrp_rect *) a;
527 const stbrp_rect *q = (const stbrp_rect *) b;
528 if (p->h > q->h)
529 return -1;
530 if (p->h < q->h)
531 return 1;
532 return (p->w > q->w) ? -1 : (p->w < q->w);
533}
534
535static int STBRP__CDECL rect_original_order(const void *a, const void *b)
536{
537 const stbrp_rect *p = (const stbrp_rect *) a;
538 const stbrp_rect *q = (const stbrp_rect *) b;
539 return (p->was_packed < q->was_packed) ? -1 : (p->was_packed > q->was_packed);
540}
541
542STBRP_DEF int stbrp_pack_rects(stbrp_context *context, stbrp_rect *rects, int num_rects)
543{
544 int i, all_rects_packed = 1;
545
546 // we use the 'was_packed' field internally to allow sorting/unsorting
547 for (i=0; i < num_rects; ++i) {
548 rects[i].was_packed = i;
549 }
550
551 // sort according to heuristic
552 STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_height_compare);
553
554 for (i=0; i < num_rects; ++i) {
555 if (rects[i].w == 0 || rects[i].h == 0) {
556 rects[i].x = rects[i].y = 0; // empty rect needs no space
557 } else {
558 stbrp__findresult fr = stbrp__skyline_pack_rectangle(context, rects[i].w, rects[i].h);
559 if (fr.prev_link) {
560 rects[i].x = (stbrp_coord) fr.x;
561 rects[i].y = (stbrp_coord) fr.y;
562 } else {
563 rects[i].x = rects[i].y = STBRP__MAXVAL;
564 }
565 }
566 }
567
568 // unsort
569 STBRP_SORT(rects, num_rects, sizeof(rects[0]), rect_original_order);
570
571 // set was_packed flags and all_rects_packed status
572 for (i=0; i < num_rects; ++i) {
573 rects[i].was_packed = !(rects[i].x == STBRP__MAXVAL && rects[i].y == STBRP__MAXVAL);
574 if (!rects[i].was_packed)
575 all_rects_packed = 0;
576 }
577
578 // return the all_rects_packed status
579 return all_rects_packed;
580}
581#endif
582
583/*
584------------------------------------------------------------------------------
585This software is available under 2 licenses -- choose whichever you prefer.
586------------------------------------------------------------------------------
587ALTERNATIVE A - MIT License
588Copyright (c) 2017 Sean Barrett
589Permission is hereby granted, free of charge, to any person obtaining a copy of
590this software and associated documentation files (the "Software"), to deal in
591the Software without restriction, including without limitation the rights to
592use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
593of the Software, and to permit persons to whom the Software is furnished to do
594so, subject to the following conditions:
595The above copyright notice and this permission notice shall be included in all
596copies or substantial portions of the Software.
597THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
598IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
599FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
600AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
601LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
602OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
603SOFTWARE.
604------------------------------------------------------------------------------
605ALTERNATIVE B - Public Domain (www.unlicense.org)
606This is free and unencumbered software released into the public domain.
607Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
608software, either in source code form or as a compiled binary, for any purpose,
609commercial or non-commercial, and by any means.
610In jurisdictions that recognize copyright laws, the author or authors of this
611software dedicate any and all copyright interest in the software to the public
612domain. We make this dedication for the benefit of the public at large and to
613the detriment of our heirs and successors. We intend this dedication to be an
614overt act of relinquishment in perpetuity of all present and future rights to
615this software under copyright law.
616THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
617IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
618FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
619AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
620ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
621WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
622------------------------------------------------------------------------------
623*/
624