// stb_rect_pack.h - v0.08 - 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: // // 0.08 (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 in the public domain. Where that dedication is not // recognized, you are granted a perpetual, irrevocable license to copy, // distribute, and modify 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 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 *, stbrp_node *first, int x0, int width, int *pwaste) { //(void)c; stbrp_node *node = first; int x1 = x0 + width; int min_y, visited_width, waste_area; 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) { stbrp_rect *p = (stbrp_rect *) a; stbrp_rect *q = (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) { stbrp_rect *p = (stbrp_rect *) a; stbrp_rect *q = (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) { stbrp_rect *p = (stbrp_rect *) a; stbrp_rect *q = (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