79 lines
2.5 KiB
C
79 lines
2.5 KiB
C
#include <hierarchy.h>
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#include <stdio.h>
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typedef struct {
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double x, y;
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} Position;
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// Forward declare component so we can use it from functions other than main
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ECS_COMPONENT_DECLARE(Position);
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void iterate_tree(ecs_world_t *ecs, ecs_entity_t e, Position p_parent) {
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// Print hierarchical name of entity & the entity type
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char *path_str = ecs_get_fullpath(ecs, e);
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char *type_str = ecs_type_str(ecs, ecs_get_type(ecs, e));
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printf("%s [%s]\n", path_str, type_str);
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ecs_os_free(type_str);
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ecs_os_free(path_str);
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// Get entity position
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const Position *ptr = ecs_get(ecs, e, Position);
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// Calculate actual position
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Position p_actual = {ptr->x + p_parent.x, ptr->y + p_parent.y};
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printf("{%f, %f}\n\n", p_actual.x, p_actual.y);
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// Iterate children recursively
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ecs_iter_t it = ecs_children(ecs, e);
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while (ecs_children_next(&it)) {
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for (int i = 0; i < it.count; i ++) {
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iterate_tree(ecs, it.entities[i], p_actual);
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}
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}
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}
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int main(int argc, char *argv[]) {
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ecs_world_t *ecs = ecs_init_w_args(argc, argv);
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ECS_COMPONENT_DEFINE(ecs, Position);
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ECS_TAG(ecs, Star);
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ECS_TAG(ecs, Planet);
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ECS_TAG(ecs, Moon);
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// Create a simple hierarchy.
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// Hierarchies use ECS relationships and the builtin flecs::ChildOf relationship to
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// create entities as children of other entities.
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ecs_entity_t sun = ecs_new_entity(ecs, "Sun");
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ecs_add(ecs, sun, Star);
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ecs_set(ecs, sun, Position, {1, 1});
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ecs_entity_t mercury = ecs_new_entity(ecs, "Mercury");
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ecs_add_pair(ecs, mercury, EcsChildOf, sun);
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ecs_add(ecs, mercury, Planet);
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ecs_set(ecs, mercury, Position, {1, 1});
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ecs_entity_t venus = ecs_new_entity(ecs, "Venus");
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ecs_add_pair(ecs, venus, EcsChildOf, sun);
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ecs_add(ecs, venus, Planet);
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ecs_set(ecs, venus, Position, {2, 2});
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ecs_entity_t earth = ecs_new_entity(ecs, "Earth");
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ecs_add_pair(ecs, earth, EcsChildOf, sun);
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ecs_add(ecs, earth, Planet);
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ecs_set(ecs, earth, Position, {3, 3});
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ecs_entity_t moon = ecs_new_entity(ecs, "Moon");
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ecs_add_pair(ecs, moon, EcsChildOf, earth);
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ecs_add(ecs, moon, Moon);
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ecs_set(ecs, moon, Position, {0.1, 0.1});
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// Is the Moon a child of Earth?
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printf("Child of Earth? %d\n", ecs_has_pair(ecs, moon, EcsChildOf, earth));
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// Do a depth-first walk of the tree
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iterate_tree(ecs, sun, (Position){0, 0});
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return ecs_fini(ecs);
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}
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