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accumulate forces and impulses in one pass

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This commit is contained in:
jacob 2024-08-22 11:33:09 -05:00
parent 0d33c5746f
commit 687ebb4eb9
2 changed files with 29 additions and 35 deletions
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9
src/entity.h
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@ -110,15 +110,8 @@ struct entity {
/* ====================================================================== */ /* ====================================================================== */
/* Impulse */ /* Impulse */
/* ENTITY_PROP_IMPULSE */
/* Applies impulse velocity to parent entity */
struct v2 impulse;
/* ====================================================================== */
/* Impulse */
/* ENTITY_PROP_FORCE */ /* ENTITY_PROP_FORCE */
/* ENTITY_PROP_IMPULSE */
/* Applies force to parent entity */ /* Applies force to parent entity */
struct v2 force; struct v2 force;

55
src/game.c
View File

@ -96,6 +96,18 @@ INTERNAL struct game_cmd_array pop_cmds(struct arena *arena)
return array; return array;
} }
/* ========================== *
* Activate
* ========================== */
INTERNAL void activate_now(struct entity *ent)
{
entity_enable_prop(ent, ENTITY_PROP_ACTIVE);
ent->activation_tick = G.tick.tick_id;
ent->verlet_xform = entity_get_xform(ent);
++ent->continuity_gen;
}
/* ========================== * /* ========================== *
* Test * Test
* ========================== */ * ========================== */
@ -180,21 +192,11 @@ INTERNAL void spawn_test_entities(void)
f32 width = (f32)DEFAULT_CAMERA_WIDTH; f32 width = (f32)DEFAULT_CAMERA_WIDTH;
f32 height = (f32)DEFAULT_CAMERA_HEIGHT; f32 height = (f32)DEFAULT_CAMERA_HEIGHT;
e->camera_quad_xform = XFORM_TRS(.s = V2(width, height)); e->camera_quad_xform = XFORM_TRS(.s = V2(width, height));
activate_now(e);
} }
} }
/* ========================== *
* Activate
* ========================== */
INTERNAL void activate_now(struct entity *ent)
{
entity_enable_prop(ent, ENTITY_PROP_ACTIVE);
ent->activation_tick = G.tick.tick_id;
ent->verlet_xform = entity_get_xform(ent);
++ent->continuity_gen;
}
/* ========================== * /* ========================== *
* Update * Update
* ========================== */ * ========================== */
@ -566,7 +568,7 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
/* Ground friction */ /* Ground friction */
if (!v2_eq(velocity, V2(0, 0))) { if (!v2_eq(velocity, V2(0, 0))) {
/* FIXME: Incorrect behavior at low FPS & low entity density */ /* FIXME: Incorrect behavior at low FPS & low entity density */
const f32 clamp_epsilon = 0.025; const f32 clamp_epsilon = 0.001;
f32 velocity_len = v2_len(velocity); f32 velocity_len = v2_len(velocity);
if (velocity_len >= clamp_epsilon) { if (velocity_len >= clamp_epsilon) {
f32 force_len = -velocity_len * ent->ground_friction; f32 force_len = -velocity_len * ent->ground_friction;
@ -576,9 +578,10 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
activate_now(force); activate_now(force);
} else { } else {
/* If velocity is below clamp_epsilon, stop entity movement. */ /* If velocity is below clamp_epsilon, stop entity movement. */
f32 mass = ent->mass_unscaled * xform_get_determinant(xf);
struct entity *impulse = entity_alloc(ent); struct entity *impulse = entity_alloc(ent);
entity_enable_prop(impulse, ENTITY_PROP_IMPULSE); entity_enable_prop(impulse, ENTITY_PROP_IMPULSE);
impulse->impulse = v2_neg(velocity); impulse->force = v2_mul(v2_neg(velocity), mass);
activate_now(impulse); activate_now(impulse);
} }
} }
@ -599,22 +602,20 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
struct v2 acceleration = V2(0, 0); struct v2 acceleration = V2(0, 0);
/* Apply impulses */ /* Apply forces and impulses */
for (struct entity *child = entity_from_handle(store, ent->first); child->valid; child = entity_from_handle(store, child->next)) { for (struct entity *child = entity_from_handle(store, ent->first); child->valid; child = entity_from_handle(store, child->next)) {
if (entity_has_prop(child, ENTITY_PROP_IMPULSE)) { b32 is_force = entity_has_prop(child, ENTITY_PROP_FORCE);
struct v2 impulse_acceleration = v2_div(child->impulse, mass); b32 is_impulse = entity_has_prop(child, ENTITY_PROP_IMPULSE);
acceleration = v2_add(acceleration, impulse_acceleration); if (is_force || is_impulse) {
struct v2 force_accel = v2_div(child->force, mass);
if (!is_impulse) {
force_accel = v2_mul(force_accel, dt);
}
acceleration = v2_add(acceleration, force_accel);
entity_enable_prop(child, ENTITY_PROP_RELEASE); entity_enable_prop(child, ENTITY_PROP_RELEASE);
} }
}
/* Apply forces */
for (struct entity *child = entity_from_handle(store, ent->first); child->valid; child = entity_from_handle(store, child->next)) {
if (entity_has_prop(child, ENTITY_PROP_FORCE)) {
struct v2 force_acceleration = v2_mul(v2_div(child->force, mass), dt);
acceleration = v2_add(acceleration, force_acceleration);
entity_enable_prop(child, ENTITY_PROP_RELEASE);
}
} }
/* Verlet integration */ /* Verlet integration */
@ -717,7 +718,7 @@ INTERNAL void game_update(struct game_cmd_array game_cmds)
/* Create impulse */ /* Create impulse */
struct entity *impulse = entity_alloc(ent); struct entity *impulse = entity_alloc(ent);
impulse->impulse = velocity; impulse->force = velocity;
entity_enable_prop(impulse, ENTITY_PROP_IMPULSE); entity_enable_prop(impulse, ENTITY_PROP_IMPULSE);
} }
} }