63 lines
1.9 KiB
C
63 lines
1.9 KiB
C
#include <basics.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, Velocity;
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void Move(ecs_iter_t *it) {
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Position *p = ecs_field(it, Position, 1);
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const Velocity *v = ecs_field(it, Velocity, 2);
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for (int i = 0; i < it->count; i ++) {
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p[i].x += v[i].x;
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p[i].y += v[i].y;
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printf("%s: {%f, %f}\n", ecs_get_name(it->world, 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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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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ECS_COMPONENT(ecs, Velocity);
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// Create a system for Position, Velocity.
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ecs_entity_t move = ecs_system(ecs, {
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// Systems are entities, and by initializing the .entity field we can
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// set some additional properties for the system like a name. While this
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// is not mandatory, it makes a system easier to find in tools like the
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// explorer (https://www.flecs.dev/explorer/).
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.entity = ecs_entity(ecs, {
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.name = "Move"
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}),
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.query.filter.terms = {
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{ .id = ecs_id(Position) },
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{ .id = ecs_id(Velocity), .inout = EcsIn }
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},
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.callback = Move
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});
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// C applications can also use the ECS_SYSTEM convenience macro:
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// ECS_SYSTEM(ecs, Move, 0, Position, [in] Velocity);
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// Create a few test entities for a Position, Velocity query
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ecs_entity_t e1 = ecs_new_entity(ecs, "e1");
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ecs_set(ecs, e1, Position, {10, 20});
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ecs_set(ecs, e1, Velocity, {1, 2});
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ecs_entity_t e2 = ecs_new_entity(ecs, "e2");
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ecs_set(ecs, e2, Position, {10, 20});
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ecs_set(ecs, e2, Velocity, {3, 4});
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// This entity will not match as it does not have Position, Velocity
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ecs_entity_t e3 = ecs_new_entity(ecs, "e3");
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ecs_set(ecs, e3, Position, {10, 20});
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// Run the system
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ecs_run(ecs, move, 0.0f, NULL);
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return ecs_fini(ecs);
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}
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