begin entity xform tree refactor

src/entity.c

@@ -1,7 +1,13 @@
 #include "entity.h"
 #include "math.h"
 
+/* Accessed via entity_store_nil() */
+READONLY struct entity_store _g_entity_store_nil = {
+    0
+};
+
 /* Accessed via entity_nil() */
+/* TODO: Allocate nil entity in nil store */
 READONLY struct entity _g_entity_nil = {
     .xform = XFORM_IDENT_NOCAST,
     .xform_world = XFORM_IDENT_NOCAST,
@@ -13,10 +19,19 @@ READONLY struct entity _g_entity_nil = {
  * Store allocation
  * ========================== */
 
-struct entity_store entity_store_alloc(void)
+struct entity_store *entity_store_alloc(void)
 {
-    struct entity_store store = { 0 };
-    store.arena = arena_alloc(GIGABYTE(64));
+    struct arena arena = arena_alloc(GIGABYTE(64));
+    struct entity_store *store = arena_push_zero(&arena, struct entity_store);
+    store->arena = arena;
+    store->entities = arena_dry_push(&arena, struct entity);
+
+    /* Special entity for keeping track of store offset */
+    struct entity *offset_entity = entity_alloc(store);
+    offset_entity->valid = false;
+    offset_entity->store_offset = (u64)store->entities - (u64)store;
+    ASSERT(offset_entity->handle.idx == 0);  /* Must be first entity in array */
+
     return store;
 }
 
@@ -27,10 +42,14 @@ void entity_store_release(struct entity_store *store)
 
 void entity_store_copy_replace(struct entity_store *dest, struct entity_store *src)
 {
-    struct arena orig_arena = dest->arena;
+    struct arena dest_arena = dest->arena;
+    struct entity *dest_entities = dest->entities;
+    u64 dest_store_offset = dest_entities[0].store_offset;
     MEMCPY_STRUCT(dest, src);
-    dest->arena = orig_arena;
-    arena_copy_replace(&dest->arena, &src->arena);
+    arena_copy_replace(&dest_arena, &src->arena);
+    dest->arena = dest_arena;
+    dest->entities = dest_entities;
+    dest->entities[0].store_offset = dest_store_offset;
 }
 
 /* ========================== *
@@ -40,48 +59,41 @@ void entity_store_copy_replace(struct entity_store *dest, struct entity_store *s
 struct entity *entity_alloc(struct entity_store *store)
 {
     struct entity *entity = NULL;
+    struct entity_handle handle = { 0 };
     if (store->first_free.gen) {
         /* Reuse from free list */
         entity = entity_from_handle(store, store->first_free);
+        handle = entity->handle;
         store->first_free = entity->next_free;
-        entity->next_free = (struct entity_handle) { 0 };
     } else {
         /* Make new */
-        u64 idx = store->count++;
         entity = arena_push(&store->arena, struct entity);
-        *entity = *entity_nil();
-        entity->handle = (struct entity_handle) { .gen = 1, .idx = idx };
+        handle = (struct entity_handle) { .gen = 1, .idx = store->count++ };
     }
+    *entity = *entity_nil();
+    entity->handle = handle;
+    entity->valid = true;
     return entity;
 }
 
 void entity_release(struct entity_store *store, struct entity *entity)
 {
-    struct entity_handle handle = (struct entity_handle) { .gen = entity->handle.gen, .idx = entity->handle.idx };
-    *entity = *entity_nil();
-    entity->handle = handle;
+    /* FIXME: Unlink entity */
+    ++entity->handle.gen;
+    entity->valid = false;
     entity->next_free = store->first_free;
-    store->first_free = handle;
+    store->first_free = entity->handle;
 }
 
 /* ========================== *
  * Query
- * ========================== */
+ * ==========================  */
 
-struct entity_array entity_store_as_array(struct entity_store *store)
-{
-    return (struct entity_array) {
-        .entities = (struct entity *)store->arena.base,
-        .count = store->count
-    };
-}
-
-/* Returns a valid entity or nil entity. Always safe to read result, need to check to write. */
+/* Returns a valid entity or nil entity. Always safe to read result, need to check `valid` to write. */
 struct entity *entity_from_handle(struct entity_store *store, struct entity_handle handle)
 {
     if (handle.idx < store->count) {
-        struct entity *entities = (struct entity *)store->arena.base;
-        struct entity *entity = &entities[handle.idx];
+        struct entity *entity = &store->entities[handle.idx];
         if (entity->handle.gen == handle.gen) {
             return entity;
         }
@@ -91,9 +103,10 @@ struct entity *entity_from_handle(struct entity_store *store, struct entity_hand
 
 struct entity *entity_find_first_match_one(struct entity_store *store, enum entity_prop prop)
 {
-    struct entity_array entities_array = entity_store_as_array(store);
-    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
-        struct entity *ent = &entities_array.entities[entity_index];
+    u64 count = store->count;
+    struct entity *entities = store->entities;
+    for (u64 entity_index = 0; entity_index < count; ++entity_index) {
+        struct entity *ent = &entities[entity_index];
         if (ent->valid && entity_has_prop(ent, prop)) {
             return ent;
         }
@@ -103,9 +116,10 @@ struct entity *entity_find_first_match_one(struct entity_store *store, enum enti
 
 struct entity *entity_find_first_match_all(struct entity_store *store, struct entity_prop_array props)
 {
-    struct entity_array entities_array = entity_store_as_array(store);
-    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
-        struct entity *ent = &entities_array.entities[entity_index];
+    u64 count = store->count;
+    struct entity *entities = store->entities;
+    for (u64 entity_index = 0; entity_index < count; ++entity_index) {
+        struct entity *ent = &entities[entity_index];
         if (ent->valid) {
             b32 all = true;
             for (u64 i = 0; i < props.count; ++i) {
@@ -122,6 +136,62 @@ struct entity *entity_find_first_match_all(struct entity_store *store, struct en
     return entity_nil();
 }
 
+/* ========================== *
+ * Xform
+ * ========================== */
+
+
+
+
+
+/* TODO: Move this */
+INTERNAL struct entity_store *entity_get_store(struct entity *ent)
+{
+    struct entity_store *store = entity_store_nil();
+    if (ent->valid) {
+        struct entity *first_entity = ent - ent->handle.idx;
+        u64 store_offset = first_entity->store_offset;
+        store = (struct entity_store *)((u64)first_entity - store_offset);
+        ASSERT(store->entities == first_entity);
+    }
+    return store;
+}
+
+
+
+
+struct xform entity_get_local_xform(struct entity *ent)
+{
+    return ent->xform;
+}
+
+void entity_set_local_xform(struct entity *ent, struct xform xf)
+{
+    ent->xform = xf;
+}
+
+struct xform entity_get_global_xform(struct entity *ent)
+{
+    /* TODO: Remove this */
+    return ent->xform_world;
+}
+
+void entity_set_global_xform(struct entity *ent, struct xform xf)
+{
+    /* TODO: Remove this */
+    struct entity_store *store = entity_get_store(ent);
+
+    struct entity *parent = entity_from_handle(store, ent->parent);
+
+    struct xform parent_global = parent->xform_world;
+    struct xform child_global = xf;
+
+    struct xform child_local = xform_mul(xform_invert(parent_global), child_global);
+
+    ent->xform = child_local;
+    ent->xform_world = child_global;
+}
+
 /* ========================== *
  * Tree
  * ========================== */
@@ -143,3 +213,5 @@ void entity_link(struct entity_store *store, struct entity *parent, struct entit
         parent->first = child->handle;
     }
 }
+
+/* TODO: entity_unlink() */

src/entity.h

@@ -29,16 +29,20 @@ struct entity_store {
     struct arena arena;
     u64 count;
     struct entity_handle first_free;
+    struct entity *entities;
 };
 
 struct entity {
+    /* Metadata */
     b32 valid;
     struct entity_handle handle;
     u64 continuity_gen;
     u64 props[(ENTITY_PROP_COUNT + 63) / 64];
-
     struct entity_handle next_free;
 
+    /* Special value stored in first entity in store array */
+    u64 store_offset;
+
     /* Tree */
     struct entity_handle parent;
     struct entity_handle next;
@@ -124,6 +128,12 @@ INLINE struct entity *entity_nil(void)
     return &_g_entity_nil;
 }
 
+INLINE struct entity_store *entity_store_nil(void)
+{
+    extern READONLY struct entity_store _g_entity_store_nil;
+    return &_g_entity_store_nil;
+}
+
 /* ========================== *
  * Property helpers
  * ========================== */
@@ -153,8 +163,10 @@ INLINE b32 entity_has_prop(struct entity *entity, enum entity_prop prop)
  * Entity functions
  * ========================== */
 
+INLINE struct entity_array entity_store_as_array(struct entity_store *store) { return (struct entity_array) { .count = store->count, .entities = store->entities }; }
+
 /* Entity store */
-struct entity_store entity_store_alloc(void);
+struct entity_store *entity_store_alloc(void);
 void entity_store_release(struct entity_store *store);
 void entity_store_copy_replace(struct entity_store *dest, struct entity_store *src);
 
@@ -162,11 +174,18 @@ void entity_store_copy_replace(struct entity_store *dest, struct entity_store *s
 struct entity *entity_alloc(struct entity_store *store);
 void entity_release(struct entity_store *store, struct entity *entity);
 
-struct entity_array entity_store_as_array(struct entity_store *store);
+/* Xform */
+struct xform entity_get_local_xform(struct entity *ent);
+void entity_set_local_xform(struct entity *ent, struct xform xf);
+struct xform entity_get_global_xform(struct entity *ent);
+void entity_set_global_xform(struct entity *ent, struct xform xf);
+
+/* Query */
 struct entity *entity_from_handle(struct entity_store *store, struct entity_handle handle);
 struct entity *entity_find_first_match_one(struct entity_store *store, enum entity_prop prop);
 struct entity *entity_find_first_match_all(struct entity_store *store, struct entity_prop_array props);
 
+/* Tree */
 void entity_link(struct entity_store *store, struct entity *parent, struct entity *child);
 
 #endif

src/game.c

@@ -137,11 +137,11 @@ INTERNAL void recalculate_world_xforms_recurse(struct entity *parent)
         child->sprite_xform_world = sprite_xform_world;
 
         /* Append sub-children to stack */
-        struct entity *subchild = entity_from_handle(&G.world.entity_store, child->last);
+        struct entity *subchild = entity_from_handle(G.world.entity_store, child->last);
         while (subchild->valid) {
             *arena_push(scratch.arena, struct stack_node) = (struct stack_node) { .entity = subchild, .parent_xform_world = xform_world };
             ++stack_count;
-            subchild = entity_from_handle(&G.world.entity_store, subchild->prev);
+            subchild = entity_from_handle(G.world.entity_store, subchild->prev);
         }
     }
 
@@ -173,14 +173,13 @@ INTERNAL void game_update(void)
             struct v2 size = V2(1, 1);
             f32 r = 0;
 
-            struct entity *e = entity_alloc(&G.world.entity_store);
-            e->valid = true;
+            struct entity *e = entity_alloc(G.world.entity_store);
             e->xform = XFORM_TRS(.t = pos, .r = r, .s = size);
 
             e->sprite = sprite_tag_from_path(STR("res/graphics/tim.ase"));
-            //e->sprite_span_name = STR("idle.unarmed");
+            e->sprite_span_name = STR("idle.unarmed");
             //e->sprite_span_name = STR("idle.one_handed");
-            e->sprite_span_name = STR("idle.two_handed");
+            //e->sprite_span_name = STR("idle.two_handed");
 
             entity_enable_prop(e, ENTITY_PROP_PLAYER_CONTROLLED);
             e->player_max_speed = 4.f;
@@ -196,8 +195,7 @@ INTERNAL void game_update(void)
 
         /* Camera ent */
         {
-            struct entity *e = entity_alloc(&G.world.entity_store);
-            e->valid = true;
+            struct entity *e = entity_alloc(G.world.entity_store);
             e->xform = XFORM_IDENT;
 
             entity_enable_prop(e, ENTITY_PROP_CAMERA);
@@ -214,7 +212,7 @@ INTERNAL void game_update(void)
     G.world.tick_ts = sys_timestamp();
     G.world.dt = max_f64(0.0, (1.0 / GAME_FPS) * G.world.timescale);
     G.world.time += G.world.dt;
-    struct entity_array entities_array =  entity_store_as_array(&G.world.entity_store);
+    struct entity_array entities_array =  entity_store_as_array(G.world.entity_store);
 
     /* ========================== *
      * Process game cmds
@@ -240,7 +238,7 @@ INTERNAL void game_update(void)
                 for (u64 i = 0; i < entities_array.count; ++i) {
                     struct entity *ent = &entities_array.entities[i];
                     if (ent->valid) {
-                        entity_release(&G.world.entity_store, ent);
+                        entity_release(G.world.entity_store, ent);
                     }
                 }
             } break;
@@ -338,7 +336,7 @@ INTERNAL void game_update(void)
         /* ENTITY_PROP_TEST */
         if (entity_has_prop(ent, ENTITY_PROP_TEST) && !ent->test_initialized) {
             ent->test_initialized = true;
-            ent->test_start_rel_xform = ent->xform;
+            ent->test_start_rel_xform = entity_get_local_xform(ent);
             ent->test_start_sprite_xform = ent->sprite_xform;
         }
 
@@ -350,14 +348,14 @@ INTERNAL void game_update(void)
             /* Update focus */
             ent->focus = G.world.player_aim;
 
-            /* Solve for missing angle using law of sines */
+            struct xform xf = entity_get_global_xform(ent);
+
+            /* Solve for final angle using law of sines */
             f32 final_xf_angle;
             {
                 struct sprite_sheet *sheet = sprite_sheet_from_tag_await(sprite_frame_scope, ent->sprite);
                 struct sprite_sheet_slice slice = sprite_sheet_get_slice(sheet, STR("hold"), ent->animation_frame);
 
-                struct xform xf = ent->xform_world;
-
                 f32 forward_hold_angle_offset;
                 {
                     struct xform xf_unrotated = xform_with_rotation(xf, 0);
@@ -384,7 +382,7 @@ INTERNAL void game_update(void)
             }
 
             if (!F32_IS_NAN(final_xf_angle)) {
-                ent->xform = xform_with_rotation(ent->xform_world, final_xf_angle);
+                entity_set_global_xform(ent, xform_with_rotation(ent->xform_world, final_xf_angle));
             }
         }
 
@@ -407,9 +405,11 @@ INTERNAL void game_update(void)
             s = v2_add(s, xform_get_scale(ent->test_start_rel_xform));
 
 
-            ent->xform.og = og;
-            ent->xform = xform_with_rotation(ent->xform, r);
-            ent->xform = xform_with_scale(ent->xform, s);
+            struct xform xf = entity_get_local_xform(ent);
+            xf.og = og;
+            xf= xform_with_rotation(xf, r);
+            xf= xform_with_scale(ent->xform, s);
+            entity_set_local_xform(ent, xf);
         }
     }
 
@@ -454,7 +454,9 @@ INTERNAL void game_update(void)
             ent->velocity = v2_add(ent->velocity, a);
 
             /* Apply velocity to position */
-            ent->xform.og = v2_add(ent->xform.og, v2_mul(ent->velocity, dt));
+            struct xform xf = entity_get_global_xform(ent);
+            xf.og = v2_add(xf.og, v2_mul(ent->velocity, dt));
+            entity_set_global_xform(ent, xf);
         }
     }
 
@@ -480,12 +482,12 @@ INTERNAL void game_update(void)
 
         /* Camera follow */
         if (entity_has_prop(ent, ENTITY_PROP_CAMERA)) {
-            struct entity *follow = entity_from_handle(&G.world.entity_store, ent->camera_follow);
+            struct entity *follow = entity_from_handle(G.world.entity_store, ent->camera_follow);
 
             if (entity_has_prop(follow, ENTITY_PROP_PLAYER_CONTROLLED)) {
                 f32 aspect_ratio = 1.0;
                 {
-                    struct xform quad_xf = xform_mul(ent->xform_world, ent->camera_quad_xform);
+                    struct xform quad_xf = xform_mul(entity_get_global_xform(ent), ent->camera_quad_xform);
                     struct v2 camera_size = xform_get_scale(quad_xf);
                     if (!v2_eq(camera_size, V2(0, 0))) {
                         aspect_ratio = camera_size.x / camera_size.y;
@@ -494,7 +496,7 @@ INTERNAL void game_update(void)
                 f32 ratio_y = 0.33f;
                 f32 ratio_x = ratio_y / aspect_ratio;
                 struct v2 camera_focus_dir = v2_mul_v2(follow->focus, V2(ratio_x, ratio_y));
-                struct v2 camera_focus_pos = v2_add(follow->xform_world.og, camera_focus_dir);
+                struct v2 camera_focus_pos = v2_add(entity_get_global_xform(follow).og, camera_focus_dir);
                 ent->camera_rel_xform_target = ent->xform;
                 ent->camera_rel_xform_target.og = camera_focus_pos;
             }

src/user.c

@@ -438,9 +438,9 @@ INTERNAL void user_update(void)
         G.world.player_aim = v2_lerp(t0->player_aim, t1->player_aim, tick_blend);
 
         /* Blend entities */
-        struct entity_array t0_entities =  entity_store_as_array(&t0->entity_store);
-        struct entity_array t1_entities = entity_store_as_array(&t1->entity_store);
-        struct entity_array world_entities = entity_store_as_array(&G.world.entity_store);
+        struct entity_array t0_entities =  entity_store_as_array(t0->entity_store);
+        struct entity_array t1_entities = entity_store_as_array(t1->entity_store);
+        struct entity_array world_entities = entity_store_as_array(G.world.entity_store);
 
         u64 num_entities = min_u64(t0_entities.count, t1_entities.count);
         for (u64 i = 0; i < num_entities; ++i) {
@@ -471,7 +471,7 @@ INTERNAL void user_update(void)
         tick_is_first_frame = G.world.tick_id == 0;
 #endif
     }
-    struct entity_array entities_array = entity_store_as_array(&G.world.entity_store);
+    struct entity_array entities_array = entity_store_as_array(G.world.entity_store);
 
     /* ========================== *
      * Find important entities
@@ -870,7 +870,7 @@ INTERNAL void user_update(void)
             }
 
             /* Draw hierarchy */
-            struct entity *parent = entity_from_handle(&G.world.entity_store, ent->parent);
+            struct entity *parent = entity_from_handle(G.world.entity_store, ent->parent);
             if (parent->valid) {
                 u32 color = RGBA_32_F(0.6, 0.6, 1, 0.75);
                 f32 thickness = 5;

src/world.c

@@ -18,7 +18,7 @@ void world_copy_replace(struct world *dest, struct world *src)
 
     MEMCPY_STRUCT(dest, src);
     dest->entity_store = old->entity_store;
-    entity_store_copy_replace(&dest->entity_store, &src->entity_store);
+    entity_store_copy_replace(dest->entity_store, src->entity_store);
 
     scratch_end(scratch);
 }

src/world.h

@@ -15,7 +15,7 @@ struct world {
     struct v2 player_move_dir;
     struct v2 player_aim;
 
-    struct entity_store entity_store;
+    struct entity_store *entity_store;
 };
 
 void world_alloc(struct world *world);