Properly link flecs library

engine/libs/flecs/examples/c/prefabs/basics/include/basics.h

@@ -0,0 +1,16 @@
+#ifndef BASICS_H
+#define BASICS_H
+
+/* This generated file contains includes for project dependencies */
+#include "basics/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/basics/include/basics/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef BASICS_BAKE_CONFIG_H
+#define BASICS_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/basics/project.json

@@ -0,0 +1,11 @@
+{
+    "id": "basics",
+    "type": "application",
+    "value": {
+        "description": "A simple hello world flecs application",
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/basics/src/main.c

@@ -0,0 +1,72 @@
+#include <basics.h>
+#include <stdio.h>
+
+// Prefabs are entities that can be used as templates for other entities. They
+// are created with a builtin Prefab tag, which by default excludes them from
+// queries and systems.
+//
+// Prefab instances are entities that have an IsA relationship to the prefab.
+// The IsA relationship causes instances to inherit the components from the 
+// prefab. By default all instances for a prefab share its components. 
+//
+// Inherited components save memory as they only need to be stored once for all
+// prefab instances. They also speed up the creation of prefabs, as inherited
+// components don't need to be copied to the instances.
+//
+// To get a private copy of a component, an instance can add it which is called 
+// an override. Overrides can be manual (by using add) or automatic (see the
+// override example).
+//
+// If a prefab has children, adding the IsA relationship instantiates the prefab
+// children for the instance (see hierarchy example).
+
+typedef struct { double value; } Defense;
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(ecs, Defense);
+
+    // Create a SpaceShip prefab with a Defense component.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+    ecs_set(ecs, SpaceShip, Defense, {50});
+
+    // Create a prefab instance
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_spaceship");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+
+    // Because of the IsA relationship, the instance now shares the Defense
+    // component with the prefab, and can be retrieved as a regular component:
+    const Defense *d_inst = ecs_get(ecs, inst, Defense);
+    printf("defense: %f\n", d_inst->value);
+
+    // Because the component is shared, changing the value on the prefab will
+    // also change the value for the instance:
+    ecs_set(ecs, SpaceShip, Defense, { 100 });
+    printf("defense after set: %f\n", d_inst->value); // now prints 100
+
+    // Prefab components can be iterated like regular components:
+    ecs_query_t *q = ecs_query(ecs, {
+        .filter.terms = {
+            { .id = ecs_id(Defense) }
+        }
+    });
+
+    ecs_iter_t it = ecs_query_iter(ecs, q);
+    while (ecs_query_next(&it)) {
+        Defense *d = ecs_field(&it, Defense, 1);
+        for (int i = 0; i < it.count; i ++) {
+            printf("%s: defense: %f\n", 
+                ecs_get_name(ecs, it.entities[i]), d[i].value);
+        }
+    }
+
+    // Output:
+    //  defense: 50.000000
+    //  defense after set: 100.000000
+    //  my_spaceship: defense: 100.000000
+
+    return ecs_fini(ecs);
+}
+
+

engine/libs/flecs/examples/c/prefabs/hierarchy/include/hierarchy.h

@@ -0,0 +1,16 @@
+#ifndef HIERARCHY_H
+#define HIERARCHY_H
+
+/* This generated file contains includes for project dependencies */
+#include "hierarchy/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/hierarchy/include/hierarchy/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef HIERARCHY_BAKE_CONFIG_H
+#define HIERARCHY_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/hierarchy/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "hierarchy",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/hierarchy/src/main.c

@@ -0,0 +1,38 @@
+#include <hierarchy.h>
+#include <stdio.h>
+
+// When a prefab has children, they are instantiated for an instance when the
+// IsA relationship to the prefab is added.
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    // Create a prefab hierarchy.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+        ecs_entity_t SpaceShipEngine = ecs_new_prefab(ecs, "Engine");
+        ecs_add_pair(ecs, SpaceShipEngine, EcsChildOf, SpaceShip);
+    
+        ecs_entity_t SpaceShipCockpit = ecs_new_prefab(ecs, "Cockpit");
+        ecs_add_pair(ecs, SpaceShipCockpit, EcsChildOf, SpaceShip);
+
+    // Instantiate the prefab. This also creates an Engine and Cockpit child
+    // for the instance.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_spaceship");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+    ecs_entity_t inst_engine = ecs_lookup_child(ecs, inst, "Engine");
+    ecs_entity_t inst_cockpit = ecs_lookup_child(ecs, inst, "Cockpit");
+
+    char *path = ecs_get_fullpath(ecs, inst_engine);
+    printf("instance engine:  %s\n", path);
+    ecs_os_free(path);
+
+    path = ecs_get_fullpath(ecs, inst_cockpit);
+    printf("instance cockpit: %s\n", path);
+    ecs_os_free(path);
+
+    // Output:
+    //  instance engine:  my_spaceship.Engine
+    //  instance cockpit: my_spaceship.Cockpit
+
+    return ecs_fini(ecs);
+}

engine/libs/flecs/examples/c/prefabs/nested_prefabs/include/nested_prefabs.h

@@ -0,0 +1,16 @@
+#ifndef NESTED_PREFABS_H
+#define NESTED_PREFABS_H
+
+/* This generated file contains includes for project dependencies */
+#include "nested_prefabs/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/nested_prefabs/include/nested_prefabs/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef NESTED_PREFABS_BAKE_CONFIG_H
+#define NESTED_PREFABS_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/nested_prefabs/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "nested_prefabs",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/nested_prefabs/src/main.c

@@ -0,0 +1,75 @@
+#include <nested_prefabs.h>
+#include <stdio.h>
+
+// Nested prefabs make it possible to reuse an existing prefab inside another
+// prefab. An example of where this could be useful is a car with four wheels:
+// instead of defining four times what a wheel is a Car prefab can reference an 
+// existing Wheel prefab.
+//
+// Nested prefabs can be created by adding a child that is a variant (inherits 
+// from) another prefab. For more information on variants, see the variants
+// example.
+//
+// Instantiated children from a nested prefab still inherit from the original
+// prefab. The reason for this is that an instantiated child is an exact copy
+// of the prefab child, and the prefab child only has an IsA relationship to the
+// nested prefab.
+//
+// This example shows how auto overriding (see the auto override example) can be
+// used to give instantiated children from a nested prefab a private copy of an
+// inherited component.
+
+typedef struct {
+    double value;
+} TirePressure;
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(ecs, TirePressure);
+
+    // Create a Wheel prefab, make sure each instantiated wheel has a private
+    // copy of the TirePressure component.
+    ecs_entity_t Wheel = ecs_new_prefab(ecs, "Wheel");
+    ecs_set(ecs, Wheel, TirePressure, { 32 });
+    ecs_override(ecs, Wheel, TirePressure);
+
+    // Create a Car prefab with four wheels. Note how the wheel names are
+    // prefixed with 'Car.', this is has the same effect as adding the
+    // (ChildOf, Car) relationship.
+    ecs_entity_t Car = ecs_new_prefab(ecs, "Car");
+        ecs_entity_t WheelFrontLeft = ecs_new_prefab(ecs, "Car.FrontLeft");
+        ecs_add_pair(ecs, WheelFrontLeft, EcsIsA, Wheel);
+
+        ecs_entity_t WheelFrontRight = ecs_new_prefab(ecs, "Car.FrontRight");
+        ecs_add_pair(ecs, WheelFrontRight, EcsIsA, Wheel);
+
+        ecs_entity_t WheelBackLeft = ecs_new_prefab(ecs, "Car.BackLeft");
+        ecs_add_pair(ecs, WheelBackLeft, EcsIsA, Wheel);
+
+        ecs_entity_t WheelBackRight = ecs_new_prefab(ecs, "Car.BackRight");
+        ecs_add_pair(ecs, WheelBackRight, EcsIsA, Wheel);
+
+    // Create a prefab instance.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_car");
+    ecs_add_pair(ecs, inst, EcsIsA, Car);
+
+    // Lookup one of the wheels
+    ecs_entity_t inst_front_left = ecs_lookup_child(ecs, inst, "FrontLeft");
+    
+    // The type shows that the child has a private copy of the TirePressure
+    // component, and an IsA relationship to the Wheel prefab.
+    char *type = ecs_type_str(ecs, ecs_get_type(ecs, inst_front_left));
+    printf("type: [%s]\n", type);
+    ecs_os_free(type);
+
+    // Get the TirePressure component & print its value
+    const TirePressure *p = ecs_get(ecs, inst_front_left, TirePressure);
+    printf("pressure: %f\n", p->value);
+
+    // Output
+    //  type: [TirePressure, (Identifier,Name), (ChildOf,my_car), (IsA,Wheel)]
+    //  pressure: 32.000000
+    
+    return ecs_fini(ecs);
+}

engine/libs/flecs/examples/c/prefabs/override/include/override.h

@@ -0,0 +1,16 @@
+#ifndef OVERRIDE_H
+#define OVERRIDE_H
+
+/* This generated file contains includes for project dependencies */
+#include "override/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/override/include/override/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef OVERRIDE_BAKE_CONFIG_H
+#define OVERRIDE_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/override/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "override",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/override/src/main.c

@@ -0,0 +1,78 @@
+#include <override.h>
+#include <stdio.h>
+
+// Overriding makes it possible for a prefab instance to obtain a private copy
+// of an inherited component. To override a component the regular add operation
+// is used. The overridden component will be initialized with the value of the
+// inherited component.
+//
+// In some cases a prefab instance should always have a private copy of an 
+// inherited component. This can be achieved with an auto override which can be
+// added to a prefab. Components with an auto override are automatically 
+// overridden when the prefab is instantiated.
+
+typedef struct {
+    double value;
+} Attack, Defense, Damage;
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(ecs, Attack);
+    ECS_COMPONENT(ecs, Defense);
+    ECS_COMPONENT(ecs, Damage);
+
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+
+    // Attack and Defense are properties that can be shared across many 
+    // spaceships. This saves memory, and speeds up prefab creation as we don't
+    // have to copy the values of Attack and Defense to private components.
+    ecs_set(ecs, SpaceShip, Attack, { 75 });
+    ecs_set(ecs, SpaceShip, Defense, { 100 });
+
+    // Damage is a property that is private to a spaceship, so add an auto
+    // override for it. This ensures that each prefab instance will have a
+    // private copy of the component.
+    ecs_set(ecs, SpaceShip, Damage, { 0 });
+    ecs_override(ecs, SpaceShip, Damage);
+
+    // Create a prefab instance.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_instance");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+    
+    // The entity will now have a private copy of the Damage component, but not
+    // of the Attack and Defense components. We can see this when we look at the
+    // type of the instance:
+    char *type = ecs_type_str(ecs, ecs_get_type(ecs, inst));
+    printf("instance type = [%s]\n", type);
+    ecs_os_free(type);
+
+    // Even though Attack was not automatically overridden, we can always 
+    // override it manually afterwards by adding it:
+    ecs_add(ecs, inst, Attack);
+
+    // The Attack component now shows up in the entity type:
+    type = ecs_type_str(ecs, ecs_get_type(ecs, inst));
+    printf("instance type = [%s]\n", type);
+    ecs_os_free(type);
+
+    // We can get all components on the instance, regardless of whether they
+    // are overridden or not. Note that the overridden components (Attack and
+    // Damage) are initialized with the values from the prefab component:
+    const Attack *attack = ecs_get(ecs, inst, Attack);
+    const Defense *defense = ecs_get(ecs, inst, Defense);
+    const Damage *damage = ecs_get(ecs, inst, Damage);
+
+    printf("attack: %f\n", attack->value);
+    printf("defense: %f\n", defense->value);
+    printf("damage: %f\n", damage->value);
+
+    // Output:
+    //  instance type = [Damage, (Identifier,Name), (IsA,SpaceShip)]
+    //  instance type = [Attack, Damage, (Identifier,Name), (IsA,SpaceShip)]
+    //  attack: 75.000000
+    //  defense: 100.000000
+    //  damage: 0.000000
+
+    return ecs_fini(ecs);
+}

engine/libs/flecs/examples/c/prefabs/slots/include/slots.h

@@ -0,0 +1,16 @@
+#ifndef SLOTS_H
+#define SLOTS_H
+
+/* This generated file contains includes for project dependencies */
+#include "slots/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/slots/include/slots/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef SLOTS_BAKE_CONFIG_H
+#define SLOTS_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/slots/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "slots",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/slots/src/main.c

@@ -0,0 +1,76 @@
+#include <slots.h>
+#include <stdio.h>
+
+// Slots can be combined with prefab hierarchies to make it easier to access
+// the child entities created for an instance.
+//
+// To create a slot, the SlotOf relationship is added to the child of a prefab,
+// with as relationship target the prefab for which to register the slot. When
+// the prefab is instantiated, each slot will be added as a relationship pair
+// to the instance that looks like this:
+//   (PrefabChild, InstanceChild)
+//
+// For a SpaceShip prefab and an Engine child, that pair would look like this:
+//   (SpaceShip.Engine, Instance.Engine)
+//
+// To get the entity for a slot, an application can use the regular functions
+// to inspect relationships and relationship targets (see code).
+//
+// Slots can be added to any level of a prefab hierarchy, as long as it is above
+// (a parent of) the slot itself. When the prefab tree is instantiated, the 
+// slots are added to the entities that correspond with the prefab children.
+//
+// Without slots, an application would have to rely on manually looking up 
+// entities by name to get access to the instantiated children, like what the
+// hierarchy example does.
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    // Create the same prefab hierarchy as from the hierarchy example, but now
+    // with the SlotOf relationship.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+        ecs_entity_t Engine = ecs_new_prefab(ecs, "Engine");
+        ecs_add_pair(ecs, Engine, EcsChildOf, SpaceShip);
+        ecs_add_pair(ecs, Engine, EcsSlotOf, SpaceShip);
+    
+        ecs_entity_t Cockpit = ecs_new_prefab(ecs, "Cockpit");
+        ecs_add_pair(ecs, Cockpit, EcsChildOf, SpaceShip);
+        ecs_add_pair(ecs, Cockpit, EcsSlotOf, SpaceShip);
+
+        // Add an additional child to the Cockpit prefab to demonstrate how 
+        // slots can be different from the parent. This slot could have been
+        // added to the Cockpit prefab, but instead we register it on the top
+        // level SpaceShip prefab.
+        ecs_entity_t PilotSeat = ecs_new_prefab(ecs, "PilotSeat");
+        ecs_add_pair(ecs, PilotSeat, EcsChildOf, Cockpit);
+        ecs_add_pair(ecs, PilotSeat, EcsSlotOf, SpaceShip);
+
+    // Create a prefab instance.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_spaceship");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+
+    // Get the instantiated entities for the prefab slots
+    ecs_entity_t inst_engine = ecs_get_target(ecs, inst, Engine, 0);
+    ecs_entity_t inst_cockpit = ecs_get_target(ecs, inst, Cockpit, 0);
+    ecs_entity_t inst_seat = ecs_get_target(ecs, inst, PilotSeat, 0);
+
+    char *path = ecs_get_fullpath(ecs, inst_engine);
+    printf("instance engine:  %s\n", path);
+    ecs_os_free(path);
+
+    path = ecs_get_fullpath(ecs, inst_cockpit);
+    printf("instance cockpit: %s\n", path);
+    ecs_os_free(path);
+
+    path = ecs_get_fullpath(ecs, inst_seat);
+    printf("instance seat:    %s\n", path);
+    ecs_os_free(path);
+
+    // Output:
+    //  instance engine:  my_spaceship.Engine
+    //  instance cockpit: my_spaceship.Cockpit
+    //  instance seat:    my_spaceship.Cockpit.PilotSeat
+
+    return ecs_fini(ecs);
+}

engine/libs/flecs/examples/c/prefabs/variant/include/variant.h

@@ -0,0 +1,16 @@
+#ifndef VARIANT_H
+#define VARIANT_H
+
+/* This generated file contains includes for project dependencies */
+#include "variant/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/variant/include/variant/bake_config.h

@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef VARIANT_BAKE_CONFIG_H
+#define VARIANT_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/variant/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "variant",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/variant/src/main.c

@@ -0,0 +1,101 @@
+#include <variant.h>
+#include <stdio.h>
+
+/* Prefabs can inherit from each other, which creates prefab variants. With
+ * variants applications can reuse a commmon set of components and specialize it
+ * by adding or overriding components on the variant. */
+
+typedef struct { double value; } Attack;
+typedef struct { double value; } Defense;
+typedef struct { double value; } FreightCapacity;
+typedef struct { double value; } ImpulseSpeed;
+
+typedef struct {
+    double x; 
+    double y; 
+} Position;
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(ecs, Position);
+    ECS_COMPONENT(ecs, Attack);
+    ECS_COMPONENT(ecs, Defense);
+    ECS_COMPONENT(ecs, FreightCapacity);
+    ECS_COMPONENT(ecs, ImpulseSpeed);
+
+    // Create a base prefab for SpaceShips.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+    ecs_set(ecs, SpaceShip, ImpulseSpeed, {50});
+    ecs_set(ecs, SpaceShip, Defense, {25});
+
+        // Create a Freighter variant which inherits from SpaceShip
+        ecs_entity_t Freighter = ecs_new_prefab(ecs, "Freighter");
+        ecs_add_pair(ecs, Freighter, EcsIsA, SpaceShip);
+        ecs_set(ecs, Freighter, FreightCapacity, {100});
+        ecs_set(ecs, Freighter, Defense, {50});
+
+            // Create a MammothFreighter variant which inherits from Freighter
+            ecs_entity_t MammothFreighter = ecs_new_prefab(ecs, "MammothFreighter");
+            ecs_add_pair(ecs, MammothFreighter, EcsIsA, Freighter);
+            ecs_set(ecs, MammothFreighter, FreightCapacity, {500});
+
+        // Create a Frigate variant which inherits from SpaceShip
+        ecs_entity_t Frigate = ecs_new_prefab(ecs, "Frigate");
+        ecs_add_pair(ecs, Frigate, EcsIsA, SpaceShip);
+        ecs_set(ecs, Frigate, Attack, {100});
+        ecs_set(ecs, Frigate, Defense, {75});
+        ecs_set(ecs, Frigate, ImpulseSpeed, {125});
+
+
+    // Create an instance of the MammothFreighter. This entity will inherit the
+    // ImpulseSpeed from SpaceShip, Defense from Freighter and FreightCapacity
+    // from MammothFreighter.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_freighter");
+    ecs_add_pair(ecs, inst, EcsIsA, MammothFreighter);
+
+    // Add a private Position component.
+    ecs_set(ecs, inst, Position, {10, 20});
+
+    // Instances can override inherited components to give them a private copy
+    // of the component. This freighter got an armor upgrade:
+    ecs_set(ecs, inst, Defense, {100});
+
+    // Queries can match components from multiple levels of inheritance
+    ecs_query_t *q = ecs_query(ecs, {
+        .filter.terms = {
+            { .id = ecs_id(Position) },
+            { .id = ecs_id(ImpulseSpeed) }, 
+            { .id = ecs_id(Defense) }, 
+            { .id = ecs_id(FreightCapacity) }
+        }
+    });
+
+    ecs_iter_t it = ecs_query_iter(ecs, q);
+    while (ecs_query_next(&it)) {
+        Position  *p = ecs_field(&it, Position, 1);
+        ImpulseSpeed *s = ecs_field(&it, ImpulseSpeed, 2);
+        Defense *d = ecs_field(&it, Defense, 3);
+        FreightCapacity *c = ecs_field(&it, FreightCapacity, 4);
+
+        for (int i = 0; i < it.count; i ++) {
+            printf("%s:\n", ecs_get_name(ecs, it.entities[i]));
+            printf(" - position: %f, %f\n", p[i].x, p[i].y);
+            printf(" - impulse speed: %f\n", s[i].value);
+            printf(" - defense: %f\n", d[i].value);
+            printf(" - capacity: %f\n", c[i].value);
+        }
+    }
+
+    // Note that when matching tables with shared components, entities are
+    // returned one by one. See the queries/instancing example for more details.
+
+    // Output:
+    //  my_freighter:
+    //   - position: 10.000000, 20.000000
+    //   - impulse speed: 50.000000
+    //   - defense: 100.000000
+    //   - capacity: 500.000000
+
+    return ecs_fini(ecs);
+}