97 lines
3.3 KiB
C
97 lines
3.3 KiB
C
#include <hierarchies.h>
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#include <stdio.h>
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typedef struct {
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double x;
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double y;
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} Position;
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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(ecs, Position);
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// Tags for local/ecs position
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ECS_TAG(ecs, Local);
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ECS_TAG(ecs, World);
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// Create a hierarchy. For an explanation see the entities/hierarchy example
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ecs_entity_t sun = ecs_new_entity(ecs, "Sun");
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ecs_add_pair(ecs, sun, ecs_id(Position), World);
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ecs_set_pair(ecs, sun, Position, Local, {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_pair(ecs, mercury, ecs_id(Position), World);
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ecs_set_pair(ecs, mercury, Position, Local, {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_pair(ecs, venus, ecs_id(Position), World);
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ecs_set_pair(ecs, venus, Position, Local, {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_pair(ecs, earth, ecs_id(Position), World);
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ecs_set_pair(ecs, earth, Position, Local, {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_pair(ecs, moon, ecs_id(Position), World);
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ecs_set_pair(ecs, moon, Position, Local, {0.1, 0.1});
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// Create a hierarchical query to compute the global position from the
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// local position and the parent position.
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ecs_query_t *q = ecs_query(ecs, {
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.filter.terms = {
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// Read from entity's Local position
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{ .id = ecs_pair(ecs_id(Position), Local), .inout = EcsIn },
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// Write to entity's World position
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{ .id = ecs_pair(ecs_id(Position), World), .inout = EcsOut },
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// Read from parent's World position
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{
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.id = ecs_pair(ecs_id(Position), World),
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.inout = EcsIn,
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// Get from the parent, in breadth-first order (cascade)
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.src.flags = EcsParent | EcsCascade,
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// Make parent term optional so we also match the root (sun)
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.oper = EcsOptional
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}
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}
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});
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// Do the transform
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ecs_iter_t it = ecs_query_iter(ecs, q);
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while (ecs_query_next(&it)) {
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const Position *p = ecs_field(&it, Position, 1);
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Position *p_out = ecs_field(&it, Position, 2);
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const Position *p_parent = ecs_field(&it, Position, 3);
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// Inner loop, iterates entities in archetype
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for (int i = 0; i < it.count; i ++) {
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p_out[i].x = p[i].x;
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p_out[i].y = p[i].y;
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if (p_parent) {
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p_out[i].x += p_parent->x;
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p_out[i].y += p_parent->y;
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}
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}
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}
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// Print ecs positions
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it = ecs_term_iter(ecs, &(ecs_term_t) {
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.id = ecs_pair(ecs_id(Position), World)
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});
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while (ecs_term_next(&it)) {
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Position *p = ecs_field(&it, Position, 1);
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for (int i = 0; i < it.count; i ++) {
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printf("%s: {%f, %f}\n", ecs_get_name(ecs, it.entities[i]),
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p[i].x, p[i].y);
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}
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}
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return ecs_fini(ecs);
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}
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