Kvad is a quadtree data structure implementation in C99, extracted from the Superpin clustering library.
void walk(double x, double y, void* payload, void* context) {
printf("Found %s at %f,%f", payload, x, y);
}
kvad_tree* tree = kvad_tree_create(0, 0, 1000, 1000, 16 /* max number of levels */, 16 /* max points per level */);
kvad_tree_insert(tree, 10, 10, "Place 1");
kvad_tree_insert(tree, 10, 10, "Place 2");
kvad_tree_insert(tree, 10, 10, "Place 3");
kvad_tree_find(tree, 5, 5, 10, 10, walk, NULL); // Find all points in (5,5)-(15,15) rectangle
kvad_tree_release(tree);
To enable internal assertions and checks on supplied arguments, define KVAD_ASSERTS=1.
If defined, the assertion macro Kvad uses internally will expand to a stdlib assert() call that
aborts the program if an inconstitent state is encountered. Use this in your debug builds.