void update_projectile()
{
list_node *c;
projectile *p;
for (c = PROJECTILES->next; c->next != NULL; c = c->next) {
if (((projectile *) c->data) != NULL) {
p = (projectile *) c->data;
p->x += p->xv;
p->y += p->yv;
if (--p->longevity <= 0) {
destroy_projectile(p);
}
check_projectile_collisions(p);
}
}
}
void check_projectile_collisions(projectile *p)
{
SDL_Rect a = {
p->x,
p->y,
p->w,
p->h
};
SDL_Rect b;
if (p->spawned_by != get_player_item()) {
b.x = get_player_x();
b.y = get_player_y();
b.w = get_player_stat("width");
b.h = get_player_stat("height");
if (!check_collision(a, b)) {
hit_player(p->dmg);
destroy_projectile(p);
return;
}
}
int xmin = (p->x/TILE_DIM)-2;
int ymin = (p->y/TILE_DIM)-2;
int xmax = (p->x/TILE_DIM)+2;
int ymax = (p->y/TILE_DIM)+2;
int x, y;
for (x = xmin; x <= xmax; x++) {
for (y = ymin; y <= ymax; y++) {
if (is_solid_tile(x, y)) {
b.x = x*32;
b.y = y*32;
b.w = b.h = TILE_DIM;
if (!check_collision(a, b)) {
destroy_projectile(p);
return;
}
}
}
}
list_node *entities = get_entities();
list_node *c;
entity *e;
for (c = entities->next; c->next != NULL; c = c->next) {
if (((entity *) c->data) != NULL &&
((entity *) c->data)->item != p->spawned_by) {
e = (entity *) c->data;
b.x = e->x;
b.y = e->y;
b.w = e->w;
b.h = e->h;
if (e->collideable && !check_collision(a, b)) {
hit_entity(e, p->dmg);
destroy_projectile(p);
return;
}
}
}
}
static void tick_physics(struct GameState *game_state, float dt)
{
// Projectile kinematics.
for (uint32 i = 0; i < game_state->projectile_count; ++i)
{
struct Projectile *projectile = &game_state->projectiles[i];
// r = r0 + (v*t) + (a*t^2)/2
projectile->position = vec2_add(projectile->position, vec2_mul(projectile->velocity, dt));
}
// Ship kinematics.
for (uint32 i = 0; i < game_state->ship_count; ++i)
{
struct Ship *ship = &game_state->ships[i];
vec2 move_acceleration = vec2_zero();
// v = v0 + (a*t)
ship->move_velocity = vec2_add(ship->move_velocity, vec2_mul(move_acceleration, dt));
// r = r0 + (v*t) + (a*t^2)/2
ship->position = vec2_add(vec2_add(ship->position, vec2_mul(ship->move_velocity, dt)), vec2_div(vec2_mul(move_acceleration, dt * dt), 2.0f));
}
//
// TODO: spatial hashing
//
// Projectile collision.
for (uint32 i = 0; i < game_state->projectile_count; ++i)
{
struct Projectile *projectile = &game_state->projectiles[i];
struct AABB projectile_aabb = aabb_from_transform(projectile->position, projectile->size);
// Projectile-building collision.
for (uint32 j = 0; j < game_state->building_count; ++j)
{
struct Building *building = &game_state->buildings[j];
struct AABB building_aabb = aabb_from_transform(building->position, building->size);
if (aabb_aabb_intersection(projectile_aabb, building_aabb))
{
// TODO: damage building if not friendly
destroy_projectile(game_state, projectile);
break;
}
}
// NOTE: owner may be dead and destroyed at this point, so checking for NULL might be required.
struct Ship *owner = get_ship_by_id(game_state, projectile->owner);
// Projectile-ship collision.
for (uint32 j = 0; j < game_state->ship_count; ++j)
{
struct Ship *ship = &game_state->ships[j];
if (ship->id == projectile->owner)
continue;
#if 0
// Allow projectiles to pass through teammates.
if (ship->team == projectile->team)
continue;
#endif
struct AABB ship_aabb = aabb_from_transform(ship->position, ship->size);
if (aabb_aabb_intersection(projectile_aabb, ship_aabb))
{
// Disable friendly fire.
if (ship->team != projectile->team)
damage_ship(game_state, ship, projectile->damage);
destroy_projectile(game_state, projectile);
break;
}
}
}
// TODO: optimize
// Ship collision.
if (game_state->ship_count >= 2)
{
for (uint32 i = 0; i < game_state->ship_count - 1; ++i)
{
struct Ship *a = &game_state->ships[i];
struct AABB a_aabb = aabb_from_transform(a->position, a->size);
vec2 a_center = vec2_div(vec2_add(a_aabb.min, a_aabb.max), 2.0f);
vec2 a_half_extents = vec2_div(vec2_sub(a_aabb.max, a_aabb.min), 2.0f);
// Ship-building collision.
for (uint32 j = 0; j < game_state->building_count; ++j)
{
struct Building *building = &game_state->buildings[j];
struct AABB b_aabb = aabb_from_transform(building->position, building->size);
if (aabb_aabb_intersection(a_aabb, b_aabb))
{
vec2 b_center = vec2_div(vec2_add(b_aabb.min, b_aabb.max), 2.0f);
vec2 b_half_extents = vec2_div(vec2_sub(b_aabb.max, b_aabb.min), 2.0f);
vec2 intersection = vec2_sub(vec2_abs(vec2_sub(b_center, a_center)), vec2_add(a_half_extents, b_half_extents));
if (intersection.x > intersection.y)
{
a->move_velocity.x = 0.0f;
if (a->position.x < building->position.x)
a->position.x += intersection.x/2.0f;
else
a->position.x -= intersection.x/2.0f;
}
else
{
a->move_velocity.y = 0.0f;
if (a->position.y < building->position.y)
a->position.y += intersection.y/2.0f;
else
a->position.y -= intersection.y/2.0f;
}
}
}
// Ship-ship collision.
for (uint32 j = i + 1; j < game_state->ship_count; ++j)
{
struct Ship *b = &game_state->ships[j];
struct AABB b_aabb = aabb_from_transform(b->position, b->size);
if (aabb_aabb_intersection(a_aabb, b_aabb))
{
vec2 b_center = vec2_div(vec2_add(b_aabb.min, b_aabb.max), 2.0f);
vec2 b_half_extents = vec2_div(vec2_sub(b_aabb.max, b_aabb.min), 2.0f);
vec2 intersection = vec2_sub(vec2_abs(vec2_sub(b_center, a_center)), vec2_add(a_half_extents, b_half_extents));
if (intersection.x > intersection.y)
{
if (abs_float(a->move_velocity.x) > abs_float(b->move_velocity.x))
a->move_velocity.x = 0.0f;
else
b->move_velocity.x = 0.0f;
if (a->position.x < b->position.x)
{
a->position.x += intersection.x/2.0f;
b->position.x -= intersection.x/2.0f;
}
else
{
a->position.x -= intersection.x/2.0f;
b->position.x += intersection.x/2.0f;
}
}
else
{
if (abs_float(a->move_velocity.y) > abs_float(b->move_velocity.y))
a->move_velocity.y = 0.0f;
else
b->move_velocity.y = 0.0f;
if (a->position.y < b->position.y)
{
a->position.y += intersection.y/2.0f;
b->position.y -= intersection.y/2.0f;
}
else
{
a->position.y -= intersection.y/2.0f;
b->position.y += intersection.y/2.0f;
}
}
}
}
}
}
}
