Sean Barrett
ago%!(EXTRA string=9 years)
parent
4c519106a7
commit
1c5a92440d
3 changed files with 657 additions and 2 deletions
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// stb_connected_components - v0.90 - public domain connected components on grids
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// http://github.com/nothings/stb
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//
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// Finds connected components on 2D grids for testing reachability between
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// two points, with fast updates when changing reachability (e.g. on one machine
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// it was typically 0.2ms w/ 1024x1024 grid). Each grid square must be "open" or
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// "closed" (traversable or untraversable), and grid squares are only connected
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// to their orthogonal neighbors, not diagonally.
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//
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// In one source file, create the implementation by doing something like this:
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//
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// #define STBCC_GRID_COUNT_X_LOG2 10
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// #define STBCC_GRID_COUNT_Y_LOG2 10
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// #define STB_CONNECTED_COMPONENTS_IMPLEMENTATION
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// #include "stb_connected_components.h"
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//
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// The above creates an implementation that can run on maps up to 1024x1024.
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// Map sizes must be a multiple of 32 on each axis.
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//
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// LICENSE
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//
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// This software is dual-licensed to the public domain and under the following
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// license: you are granted a perpetual, irrevocable license to copy, modify,
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// publish, and distribute this file as you see fit.
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//
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#ifndef INCLUDE_STB_CONNECTED_COMPONENTS_H |
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#define INCLUDE_STB_CONNECTED_COMPONENTS_H |
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#include <stdlib.h> |
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#include <assert.h> |
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typedef struct st_stbcc_grid stbcc_grid; |
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//////////////////////////////////////////////////////////////////////////////////////////
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//
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// initialization
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//
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// you allocate the grid data structure to this size (note that it will be very big!!!)
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extern size_t stbcc_grid_sizeof(void); |
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// initialize the grid, value of map[] is 0 = traversable, non-0 is solid
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extern void stbcc_init_grid(stbcc_grid *g, unsigned char *map, int w, int h); |
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//////////////////////////////////////////////////////////////////////////////////////////
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//
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// main functionality
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//
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// update a grid square state, 0 = traversable, non-0 is solid
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// i can add a batch-update if it's needed
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extern void stbcc_update_grid(stbcc_grid *g, int x, int y, int solid); |
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// query if two grid squares are reachable from each other
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extern int stbcc_query_grid_node_connection(stbcc_grid *g, int x1, int y1, int x2, int y2); |
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//////////////////////////////////////////////////////////////////////////////////////////
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//
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// bonus functions
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//
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// query the grid data structure for whether a given square is open or not
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extern int stbcc_query_grid_open(stbcc_grid *g, int x, int y); |
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// get a unique id for the connected component this is in; it's not necessarily
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// small, you'll need a hash table or something to remap it (or just use
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extern unsigned int stbcc_get_unique_id(stbcc_grid *g, int x, int y); |
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#endif // INCLUDE_STB_CONNECTED_COMPONENTS_H
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#ifdef STB_CONNECTED_COMPONENTS_IMPLEMENTATION |
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#if !defined(STBCC_GRID_COUNT_X_LOG2) || !defined(STBCC_GRID_COUNT_Y_LOG2) |
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#error "You must define STBCC_GRID_COUNT_X_LOG2 and STBCC_GRID_COUNT_Y_LOG2 to define the max grid supported." |
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#endif |
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#define STBCC__GRID_COUNT_X (1 << STBCC_GRID_COUNT_X_LOG2) |
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#define STBCC__GRID_COUNT_Y (1 << STBCC_GRID_COUNT_Y_LOG2) |
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#define STBCC__MAP_STRIDE (1 << (STBCC_GRID_COUNT_X_LOG2-3)) |
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#ifndef STBCC_CLUSTER_SIZE_X_LOG2 |
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#define STBCC_CLUSTER_SIZE_X_LOG2 5 |
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#endif |
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#ifndef STBCC_CLUSTER_SIZE_Y_LOG2 |
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#define STBCC_CLUSTER_SIZE_Y_LOG2 5 |
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#endif |
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#define STBCC__CLUSTER_SIZE_X (1 << STBCC_CLUSTER_SIZE_X_LOG2) |
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#define STBCC__CLUSTER_SIZE_Y (1 << STBCC_CLUSTER_SIZE_Y_LOG2) |
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#define STBCC__CLUSTER_COUNT_X_LOG2 (STBCC_GRID_COUNT_X_LOG2 - STBCC_CLUSTER_SIZE_X_LOG2) |
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#define STBCC__CLUSTER_COUNT_Y_LOG2 (STBCC_GRID_COUNT_Y_LOG2 - STBCC_CLUSTER_SIZE_Y_LOG2) |
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#define STBCC__CLUSTER_COUNT_X (1 << STBCC__CLUSTER_COUNT_X_LOG2) |
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#define STBCC__CLUSTER_COUNT_Y (1 << STBCC__CLUSTER_COUNT_Y_LOG2) |
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#if STBCC__CLUSTER_SIZE_X >= STBCC__GRID_COUNT_X || STBCC__CLUSTER_SIZE_Y >= STBCC__GRID_COUNT_Y |
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#error "STBCC_CLUSTER_SIZE_X/Y_LOG2 must be smaller than STBCC_GRID_COUNT_X/Y_LOG2" |
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#endif |
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// worst case # of clumps per cluster
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#define STBCC__MAX_CLUMPS_PER_CLUSTER_LOG2 (STBCC_CLUSTER_SIZE_X_LOG2 + STBCC_CLUSTER_SIZE_Y_LOG2-1) |
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#define STBCC__MAX_CLUMPS_PER_CLUSTER (1 << STBCC__MAX_CLUMPS_PER_CLUSTER_LOG2) |
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#define STBCC__MAX_CLUMPS (STBCC__MAX_CLUMPS_PER_CLUSTER * STBCC__CLUSTER_COUNT_X * STBCC__CLUSTER_COUNT_Y) |
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#define STBCC__NULL_CLUMPID STBCC__MAX_CLUMPS_PER_CLUSTER |
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#define STBCC__CLUSTER_X_FOR_COORD_X(x) ((x) >> STBCC_CLUSTER_SIZE_X_LOG2) |
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#define STBCC__CLUSTER_Y_FOR_COORD_Y(y) ((y) >> STBCC_CLUSTER_SIZE_Y_LOG2) |
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#define STBCC__MAP_BYTE_MASK(x,y) (1 << ((x) & 7)) |
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#define STBCC__MAP_BYTE(g,x,y) ((g)->map[y][(x) >> 3]) |
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#define STBCC__MAP_OPEN(g,x,y) (STBCC__MAP_BYTE(g,x,y) & STBCC__MAP_BYTE_MASK(x,y)) |
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typedef unsigned short stbcc__clumpid; |
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typedef unsigned char stbcc__verify_max_clumps[STBCC__MAX_CLUMPS_PER_CLUSTER < (1 << (8*sizeof(stbcc__clumpid))) ? 1 : -1]; |
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#define STBCC__MAX_EXITS_PER_CLUMP (STBCC__CLUSTER_SIZE_X + STBCC__CLUSTER_SIZE_Y) // 64
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// 2^19 * 2^6 => 2^25 exits => 2^26 => 64MB for 1024x1024
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typedef unsigned char stbcc__verify_max_exits[STBCC__MAX_EXITS_PER_CLUMP <= 256]; |
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typedef struct |
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{ |
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unsigned short clump_index:12; |
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signed short cluster_dx:2; |
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signed short cluster_dy:2; |
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} stbcc__relative_clumpid; |
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typedef union |
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{ |
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struct { |
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unsigned int clump_index:12; |
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unsigned int cluster_x:10; |
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unsigned int cluster_y:10; |
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} f; |
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unsigned int c; |
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} stbcc__global_clumpid; |
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// rebuilt cluster 3,4
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// what changes in cluster 2,4
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typedef struct |
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{ |
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stbcc__global_clumpid global_label; |
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unsigned char num_adjacent; |
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stbcc__relative_clumpid adjacent_clumps[STBCC__MAX_EXITS_PER_CLUMP]; |
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} stbcc__clump; |
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typedef struct |
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{ |
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unsigned int num_clumps; |
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stbcc__clump clump[STBCC__MAX_CLUMPS_PER_CLUSTER]; |
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} stbcc__cluster; |
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struct st_stbcc_grid |
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{ |
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int w,h,cw,ch; |
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unsigned char map[STBCC__GRID_COUNT_Y][STBCC__MAP_STRIDE]; // 1K x 1K => 1K x 128 => 128KB
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stbcc__clumpid clump_for_node[STBCC__GRID_COUNT_Y][STBCC__GRID_COUNT_X]; // 1K x 1K x 2 = 2MB
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stbcc__cluster cluster[STBCC__CLUSTER_COUNT_Y][STBCC__CLUSTER_COUNT_X]; // 1K x 1K x 0.5 x 64 x 2 = 64MB
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}; |
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int stbcc_query_grid_node_connection(stbcc_grid *g, int x1, int y1, int x2, int y2) |
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{ |
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stbcc__global_clumpid label1, label2; |
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stbcc__clumpid c1 = g->clump_for_node[y1][x1]; |
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stbcc__clumpid c2 = g->clump_for_node[y2][x2]; |
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int cx1 = STBCC__CLUSTER_X_FOR_COORD_X(x1); |
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int cy1 = STBCC__CLUSTER_Y_FOR_COORD_Y(y1); |
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int cx2 = STBCC__CLUSTER_X_FOR_COORD_X(x2); |
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int cy2 = STBCC__CLUSTER_Y_FOR_COORD_Y(y2); |
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if (c1 == STBCC__NULL_CLUMPID || c2 == STBCC__NULL_CLUMPID) |
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return 0; |
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label1 = g->cluster[cy1][cx1].clump[c1].global_label; |
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label2 = g->cluster[cy2][cx2].clump[c2].global_label; |
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if (label1.c == label2.c) |
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return 1; |
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return 0; |
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} |
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int stbcc_query_grid_open(stbcc_grid *g, int x, int y) |
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{ |
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return STBCC__MAP_OPEN(g, x, y) != 0; |
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} |
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unsigned int stbcc_get_unique_id(stbcc_grid *g, int x, int y) |
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{ |
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stbcc__clumpid c = g->clump_for_node[y][x]; |
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int cx = STBCC__CLUSTER_X_FOR_COORD_X(x); |
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int cy = STBCC__CLUSTER_Y_FOR_COORD_Y(y); |
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return g->cluster[cy][cx].clump[c].global_label.c; |
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} |
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typedef struct |
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{ |
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unsigned char x,y; |
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} stbcc__tinypoint; |
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typedef struct |
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{ |
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stbcc__tinypoint parent[STBCC__CLUSTER_SIZE_Y][STBCC__CLUSTER_SIZE_X]; // 32x32 => 2KB
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stbcc__clumpid label[STBCC__CLUSTER_SIZE_Y][STBCC__CLUSTER_SIZE_X]; |
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} stbcc__cluster_build_info; |
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static void stbcc__build_clumps_for_cluster(stbcc_grid *g, int cx, int cy); |
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static void stbcc__remove_connections_to_adjacent_cluster(stbcc_grid *g, int cx, int cy, int dx, int dy); |
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static void stbcc__add_connections_to_adjacent_cluster(stbcc_grid *g, int cx, int cy, int dx, int dy); |
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static stbcc__global_clumpid stbcc__clump_find(stbcc_grid *g, stbcc__global_clumpid n) |
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{ |
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stbcc__global_clumpid q; |
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stbcc__clump *c = &g->cluster[n.f.cluster_y][n.f.cluster_x].clump[n.f.clump_index]; |
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if (c->global_label.c == n.c) |
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return n; |
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q = stbcc__clump_find(g, c->global_label); |
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c->global_label = q; |
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return q; |
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} |
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typedef struct |
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{ |
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unsigned int cluster_x; |
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unsigned int cluster_y; |
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unsigned int clump_index; |
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} stbcc__unpacked_clumpid; |
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// @OPTIMIZE: pass in these parameters unpacked, not packed
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static void stbcc__clump_union(stbcc_grid *g, stbcc__unpacked_clumpid m, int x, int y, int idx) |
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{ |
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stbcc__clump *mc = &g->cluster[m.cluster_y][m.cluster_x].clump[m.clump_index]; |
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stbcc__clump *nc = &g->cluster[y][x].clump[idx]; |
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stbcc__global_clumpid mp = stbcc__clump_find(g, mc->global_label); |
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stbcc__global_clumpid np = stbcc__clump_find(g, nc->global_label); |
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if (mp.c == np.c) |
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return; |
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g->cluster[mp.f.cluster_y][mp.f.cluster_x].clump[mp.f.clump_index].global_label = np; |
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} |
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static void stbcc__build_connected_components_for_clumps(stbcc_grid *g) |
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{ |
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int i,j,k,h; |
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for (j=0; j < STBCC__CLUSTER_COUNT_Y; ++j) { |
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for (i=0; i < STBCC__CLUSTER_COUNT_X; ++i) { |
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stbcc__cluster *cluster = &g->cluster[j][i]; |
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for (k=0; k < (int) cluster->num_clumps; ++k) { |
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stbcc__global_clumpid m; |
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m.f.clump_index = k; |
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m.f.cluster_x = i; |
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m.f.cluster_y = j; |
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assert((int) m.f.clump_index == k && (int) m.f.cluster_x == i && (int) m.f.cluster_y == j); |
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cluster->clump[k].global_label = m; |
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} |
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} |
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} |
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for (j=0; j < STBCC__CLUSTER_COUNT_Y; ++j) { |
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for (i=0; i < STBCC__CLUSTER_COUNT_X; ++i) { |
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stbcc__cluster *cluster = &g->cluster[j][i]; |
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for (k=0; k < (int) cluster->num_clumps; ++k) { |
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stbcc__clump *clump = &cluster->clump[k]; |
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stbcc__unpacked_clumpid m; |
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m.clump_index = k; |
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m.cluster_x = i; |
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m.cluster_y = j; |
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for (h=0; h < clump->num_adjacent; ++h) { |
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unsigned int clump_index = clump->adjacent_clumps[h].clump_index; |
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unsigned int x = clump->adjacent_clumps[h].cluster_dx + i; |
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unsigned int y = clump->adjacent_clumps[h].cluster_dy + j; |
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stbcc__clump_union(g, m, x, y, clump_index); |
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} |
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} |
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} |
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} |
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for (j=0; j < STBCC__CLUSTER_COUNT_Y; ++j) { |
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for (i=0; i < STBCC__CLUSTER_COUNT_X; ++i) { |
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stbcc__cluster *cluster = &g->cluster[j][i]; |
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for (k=0; k < (int) cluster->num_clumps; ++k) { |
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stbcc__global_clumpid m; |
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m.f.clump_index = k; |
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m.f.cluster_x = i; |
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m.f.cluster_y = j; |
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stbcc__clump_find(g, m); |
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} |
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} |
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} |
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} |
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void stbcc_update_grid(stbcc_grid *g, int x, int y, int solid) |
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{ |
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int cx,cy; |
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if (!solid) { |
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if (STBCC__MAP_OPEN(g,x,y)) |
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return; |
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} else { |
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if (!STBCC__MAP_OPEN(g,x,y)) |
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return; |
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} |
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cx = STBCC__CLUSTER_X_FOR_COORD_X(x); |
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cy = STBCC__CLUSTER_Y_FOR_COORD_Y(y); |
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stbcc__remove_connections_to_adjacent_cluster(g, cx-1, cy, 1, 0); |
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stbcc__remove_connections_to_adjacent_cluster(g, cx+1, cy, -1, 0); |
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stbcc__remove_connections_to_adjacent_cluster(g, cx, cy-1, 0, 1); |
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stbcc__remove_connections_to_adjacent_cluster(g, cx, cy+1, 0,-1); |
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if (!solid) |
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STBCC__MAP_BYTE(g,x,y) |= STBCC__MAP_BYTE_MASK(x,y); |
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else |
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STBCC__MAP_BYTE(g,x,y) &= ~STBCC__MAP_BYTE_MASK(x,y); |
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stbcc__build_clumps_for_cluster(g, cx, cy); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy, -1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy, 1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy, 0,-1); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy, 0, 1); |
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stbcc__add_connections_to_adjacent_cluster(g, cx-1, cy, 1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, cx+1, cy, -1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy-1, 0, 1); |
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stbcc__add_connections_to_adjacent_cluster(g, cx, cy+1, 0,-1); |
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stbcc__build_connected_components_for_clumps(g); |
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} |
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size_t stbcc_grid_sizeof(void) |
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{ |
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return sizeof(stbcc_grid); |
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} |
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void stbcc_init_grid(stbcc_grid *g, unsigned char *map, int w, int h) |
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{ |
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int i,j,k; |
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assert(w % STBCC__CLUSTER_SIZE_X == 0); |
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assert(h % STBCC__CLUSTER_SIZE_Y == 0); |
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assert(w % 8 == 0); |
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g->w = w; |
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g->h = h; |
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g->cw = w >> STBCC_CLUSTER_SIZE_X_LOG2; |
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g->ch = h >> STBCC_CLUSTER_SIZE_Y_LOG2; |
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for (j=0; j < h; ++j) { |
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for (i=0; i < w; i += 8) { |
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unsigned char c = 0; |
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for (k=0; k < 8; ++k) |
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if (map[j*w + (i+k)] == 0) |
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c |= (1 << k); |
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g->map[j][i>>3] = c; |
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} |
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} |
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for (j=0; j < g->ch; ++j) |
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for (i=0; i < g->cw; ++i) |
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stbcc__build_clumps_for_cluster(g, i, j); |
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for (j=0; j < g->ch; ++j) { |
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for (i=0; i < g->cw; ++i) { |
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stbcc__add_connections_to_adjacent_cluster(g, i, j, -1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, i, j, 1, 0); |
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stbcc__add_connections_to_adjacent_cluster(g, i, j, 0,-1); |
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stbcc__add_connections_to_adjacent_cluster(g, i, j, 0, 1); |
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} |
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} |
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stbcc__build_connected_components_for_clumps(g); |
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for (j=0; j < g->h; ++j) |
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for (i=0; i < g->w; ++i) |
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assert(g->clump_for_node[j][i] <= STBCC__NULL_CLUMPID); |
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} |
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static void stbcc__add_clump_connection(stbcc_grid *g, int x1, int y1, int x2, int y2) |
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{ |
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stbcc__clump *clump; |
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int cx1 = STBCC__CLUSTER_X_FOR_COORD_X(x1); |
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int cy1 = STBCC__CLUSTER_Y_FOR_COORD_Y(y1); |
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int cx2 = STBCC__CLUSTER_X_FOR_COORD_X(x2); |
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int cy2 = STBCC__CLUSTER_Y_FOR_COORD_Y(y2); |
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stbcc__clumpid c1 = g->clump_for_node[y1][x1]; |
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stbcc__clumpid c2 = g->clump_for_node[y2][x2]; |
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stbcc__relative_clumpid rc; |
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assert(cx1 != cx2 || cy1 != cy2); |
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assert(abs(cx1-cx2) + abs(cy1-cy2) == 1); |
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// add connection to c2 in c1
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rc.clump_index = c2; |
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rc.cluster_dx = x2-x1; |
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rc.cluster_dy = y2-y1; |
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clump = &g->cluster[cy1][cx1].clump[c1]; |
||||
assert(clump->num_adjacent < STBCC__MAX_EXITS_PER_CLUMP); |
||||
clump->adjacent_clumps[clump->num_adjacent++] = rc; |
||||
} |
||||
|
||||
static void stbcc__remove_clump_connection(stbcc_grid *g, int x1, int y1, int x2, int y2) |
||||
{ |
||||
stbcc__clump *clump; |
||||
int i; |
||||
|
||||
int cx1 = STBCC__CLUSTER_X_FOR_COORD_X(x1); |
||||
int cy1 = STBCC__CLUSTER_Y_FOR_COORD_Y(y1); |
||||
int cx2 = STBCC__CLUSTER_X_FOR_COORD_X(x2); |
||||
int cy2 = STBCC__CLUSTER_Y_FOR_COORD_Y(y2); |
||||
|
||||
stbcc__clumpid c1 = g->clump_for_node[y1][x1]; |
||||
stbcc__clumpid c2 = g->clump_for_node[y2][x2]; |
||||
|
||||
stbcc__relative_clumpid rc; |
||||
|
||||
assert(cx1 != cx2 || cy1 != cy2); |
||||
assert(abs(cx1-cx2) + abs(cy1-cy2) == 1); |
||||
|
||||
// add connection to c2 in c1
|
||||
|
||||
rc.clump_index = c2; |
||||
rc.cluster_dx = x2-x1; |
||||
rc.cluster_dy = y2-y1; |
||||
|
||||
clump = &g->cluster[cy1][cx1].clump[c1]; |
||||
|
||||
for (i=0; i < clump->num_adjacent; ++i) |
||||
if (rc.clump_index == clump->adjacent_clumps[i].clump_index && |
||||
rc.cluster_dx == clump->adjacent_clumps[i].cluster_dx && |
||||
rc.cluster_dy == clump->adjacent_clumps[i].cluster_dy)
|
||||
break; |
||||
|
||||
if (i < clump->num_adjacent) |
||||
clump->adjacent_clumps[i] = clump->adjacent_clumps[--clump->num_adjacent]; |
||||
else |
||||
assert(0); |
||||
} |
||||
|
||||
static void stbcc__add_connections_to_adjacent_cluster(stbcc_grid *g, int cx, int cy, int dx, int dy) |
||||
{ |
||||
unsigned char connected[STBCC__MAX_CLUMPS_PER_CLUSTER/8] = { 0 }; |
||||
int x = cx * STBCC__CLUSTER_SIZE_X; |
||||
int y = cy * STBCC__CLUSTER_SIZE_Y; |
||||
int step_x, step_y=0, i, j, k, n; |
||||
|
||||
if (cx < 0 || cx >= g->cw || cy < 0 || cy >= g->ch) |
||||
return; |
||||
|
||||
if (cx+dx < 0 || cx+dx >= g->cw || cy+dy < 0 || cy+dy >= g->ch) |
||||
return; |
||||
|
||||
assert(abs(dx) + abs(dy) == 1); |
||||
|
||||
if (dx == 1) { |
||||
i = STBCC__CLUSTER_SIZE_X-1; |
||||
j = 0; |
||||
step_x = 0; |
||||
step_y = 1; |
||||
n = STBCC__CLUSTER_SIZE_Y; |
||||
} else if (dx == -1) { |
||||
i = 0; |
||||
j = 0; |
||||
step_x = 0; |
||||
step_y = 1;
|
||||
n = STBCC__CLUSTER_SIZE_Y; |
||||
} else if (dy == -1) { |
||||
i = 0; |
||||
j = 0; |
||||
step_x = 1; |
||||
step_y = 0; |
||||
n = STBCC__CLUSTER_SIZE_X; |
||||
} else if (dy == 1) { |
||||
i = 0; |
||||
j = STBCC__CLUSTER_SIZE_Y-1; |
||||
step_x = 1; |
||||
step_y = 0; |
||||
n = STBCC__CLUSTER_SIZE_X; |
||||
} else { |
||||
assert(0); |
||||
} |
||||
|
||||
for (k=0; k < n; ++k) { |
||||
if (STBCC__MAP_OPEN(g, x+i, y+j) && STBCC__MAP_OPEN(g, x+i+dx, y+j+dy)) { |
||||
stbcc__clumpid c = g->clump_for_node[y+j+dy][x+i+dx]; |
||||
if (0 == (connected[c>>3] & (1 << (c & 7)))) { |
||||
connected[c>>3] |= 1 << (c & 7); |
||||
stbcc__add_clump_connection(g, x+i, y+j, x+i+dx, y+j+dy); |
||||
} |
||||
} |
||||
i += step_x; |
||||
j += step_y; |
||||
} |
||||
} |
||||
|
||||
static void stbcc__remove_connections_to_adjacent_cluster(stbcc_grid *g, int cx, int cy, int dx, int dy) |
||||
{ |
||||
unsigned char disconnected[STBCC__MAX_CLUMPS_PER_CLUSTER/8] = { 0 }; |
||||
int x = cx * STBCC__CLUSTER_SIZE_X; |
||||
int y = cy * STBCC__CLUSTER_SIZE_Y; |
||||
int step_x, step_y=0, i, j, k, n; |
||||
|
||||
if (cx < 0 || cx >= g->cw || cy < 0 || cy >= g->ch) |
||||
return; |
||||
|
||||
if (cx+dx < 0 || cx+dx >= g->cw || cy+dy < 0 || cy+dy >= g->ch) |
||||
return; |
||||
|
||||
assert(abs(dx) + abs(dy) == 1); |
||||
|
||||
if (dx == 1) { |
||||
i = STBCC__CLUSTER_SIZE_X-1; |
||||
j = 0; |
||||
step_x = 0; |
||||
step_y = 1; |
||||
n = STBCC__CLUSTER_SIZE_Y; |
||||
} else if (dx == -1) { |
||||
i = 0; |
||||
j = 0; |
||||
step_x = 0; |
||||
step_y = 1;
|
||||
n = STBCC__CLUSTER_SIZE_Y; |
||||
} else if (dy == -1) { |
||||
i = 0; |
||||
j = 0; |
||||
step_x = 1; |
||||
step_y = 0; |
||||
n = STBCC__CLUSTER_SIZE_X; |
||||
} else if (dy == 1) { |
||||
i = 0; |
||||
j = STBCC__CLUSTER_SIZE_Y-1; |
||||
step_x = 1; |
||||
step_y = 0; |
||||
n = STBCC__CLUSTER_SIZE_X; |
||||
} else { |
||||
assert(0); |
||||
} |
||||
|
||||
for (k=0; k < n; ++k) { |
||||
if (STBCC__MAP_OPEN(g, x+i, y+j) && STBCC__MAP_OPEN(g, x+i+dx, y+j+dy)) { |
||||
stbcc__clumpid c = g->clump_for_node[y+j+dy][x+i+dx]; |
||||
if (0 == (disconnected[c>>3] & (1 << (c & 7)))) { |
||||
disconnected[c>>3] |= 1 << (c & 7); |
||||
stbcc__remove_clump_connection(g, x+i, y+j, x+i+dx, y+j+dy); |
||||
} |
||||
} |
||||
i += step_x; |
||||
j += step_y; |
||||
} |
||||
} |
||||
|
||||
static stbcc__tinypoint stbcc__incluster_find(stbcc__cluster_build_info *cbi, int x, int y) |
||||
{ |
||||
stbcc__tinypoint p,q; |
||||
p = cbi->parent[y][x]; |
||||
if (p.x == x && p.y == y) |
||||
return p; |
||||
q = stbcc__incluster_find(cbi, p.x, p.y); |
||||
cbi->parent[y][x] = q; |
||||
return q; |
||||
} |
||||
|
||||
static void stbcc__incluster_union(stbcc__cluster_build_info *cbi, int x1, int y1, int x2, int y2) |
||||
{ |
||||
stbcc__tinypoint p = stbcc__incluster_find(cbi, x1,y1); |
||||
stbcc__tinypoint q = stbcc__incluster_find(cbi, x2,y2); |
||||
|
||||
if (p.x == q.x && p.y == q.y) |
||||
return; |
||||
|
||||
cbi->parent[p.y][p.x] = q; |
||||
} |
||||
|
||||
static void stbcc__build_clumps_for_cluster(stbcc_grid *g, int cx, int cy) |
||||
{ |
||||
stbcc__cluster *c; |
||||
stbcc__cluster_build_info cbi; |
||||
int label=0; |
||||
int i,j; |
||||
int x = cx * STBCC__CLUSTER_SIZE_X; |
||||
int y = cy * STBCC__CLUSTER_SIZE_Y; |
||||
|
||||
// set initial disjoint set forest state
|
||||
for (j=0; j < STBCC__CLUSTER_SIZE_Y; ++j) { |
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X; ++i) { |
||||
cbi.parent[j][i].x = i; |
||||
cbi.parent[j][i].y = j; |
||||
} |
||||
} |
||||
|
||||
// join all sets that are connected
|
||||
for (j=0; j < STBCC__CLUSTER_SIZE_Y; ++j) { |
||||
// check down only if not on bottom row
|
||||
if (j < STBCC__CLUSTER_SIZE_Y-1) |
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X; ++i) |
||||
if (STBCC__MAP_OPEN(g,x+i,y+j) && STBCC__MAP_OPEN(g,x+i ,y+j+1)) |
||||
stbcc__incluster_union(&cbi, i,j, i,j+1); |
||||
// check right for everything but rightmost column
|
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X-1; ++i) |
||||
if (STBCC__MAP_OPEN(g,x+i,y+j) && STBCC__MAP_OPEN(g,x+i+1,y+j )) |
||||
stbcc__incluster_union(&cbi, i,j, i+1,j); |
||||
} |
||||
|
||||
// label all non-empty leaders
|
||||
for (j=0; j < STBCC__CLUSTER_SIZE_Y; ++j) { |
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X; ++i) { |
||||
stbcc__tinypoint p = cbi.parent[j][i]; |
||||
if (p.x == i && p.y == j) |
||||
if (STBCC__MAP_OPEN(g,x+i,y+j)) |
||||
cbi.label[j][i] = label++; |
||||
else |
||||
cbi.label[j][i] = STBCC__NULL_CLUMPID; |
||||
} |
||||
} |
||||
|
||||
// label all other nodes
|
||||
for (j=0; j < STBCC__CLUSTER_SIZE_Y; ++j) { |
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X; ++i) { |
||||
stbcc__tinypoint p = stbcc__incluster_find(&cbi, i,j); |
||||
if (p.x != i || p.y != j) { |
||||
if (STBCC__MAP_OPEN(g,x+i,y+j)) |
||||
cbi.label[j][i] = cbi.label[p.y][p.x]; |
||||
} |
||||
} |
||||
} |
||||
|
||||
c = &g->cluster[cy][cx]; |
||||
c->num_clumps = label; |
||||
for (i=0; i < label; ++i) |
||||
c->clump[i].num_adjacent = 0; |
||||
|
||||
for (j=0; j < STBCC__CLUSTER_SIZE_Y; ++j) |
||||
for (i=0; i < STBCC__CLUSTER_SIZE_X; ++i) { |
||||
g->clump_for_node[y+j][x+i] = cbi.label[j][i]; // @OPTIMIZE: remove cbi.label entirely
|
||||
assert(g->clump_for_node[y+j][x+i] <= STBCC__NULL_CLUMPID); |
||||
} |
||||
} |
||||
|
||||
#endif // STB_CONNECTED_COMPONENTS_IMPLEMENTATION
|
||||
Loading…
Reference in New Issue