eco2d/code/modules/source/system_items.c

#include "items.h"

#define ITEM_PICK_RADIUS 25.0f
#define ITEM_MERGER_RADIUS 75.0f
#define ITEM_ATTRACT_RADIUS 75.0f
#define ITEM_ATTRACT_FORCE 0.63f

void PickItem(ecs_iter_t *it) {
    Position *p = ecs_field(it, Position, 2);
    Inventory *inv = ecs_field(it, Inventory, 3);

    for (int i = 0; i < it->count; i++) {
        if (inv[i].pickup_time > game_time()) continue;
        size_t ents_count;
        int64_t *ents = world_chunk_query_entities(it->entities[i], &ents_count, 2);

        for (size_t j = 0; j < ents_count; j++) {
            ItemDrop *drop = 0;
            if ((drop = ecs_get_mut_if(it->world, ents[j], ItemDrop))) {
                Position *p2 = ecs_get_mut(it->world, ents[j], Position);

                float dx = p2->x - p[i].x;
                float dy = p2->y - p[i].y;
                float range = zpl_sqrt(dx*dx + dy*dy);
                if (range <= ITEM_PICK_RADIUS) {
                    uint16_t drop_id = item_find(drop->kind);
                    for (size_t k = 0; k < ITEMS_INVENTORY_SIZE; k += 1) {
                        ItemDrop *item = &inv[i].items[k];
                        uint16_t item_id = item_find(item->kind);
                        if (item_id != ASSET_INVALID && (item->quantity == 0 || (item->quantity != 0 && item->kind == drop->kind)) && item->quantity < item_max_quantity(drop_id)) {
                            uint32_t picked_count = zpl_max(0, drop->quantity);
                            picked_count = zpl_clamp(picked_count, 0, item_max_quantity(drop_id) - item->quantity);
                            item->quantity += picked_count;
                            drop->quantity -= picked_count;
                            item->kind = drop->kind;
                            entity_wake(ents[j]);

                            if (drop->quantity == 0)
                                item_despawn(ents[j]);
                            break;
                        }
                    }
                } else if (range <= ITEM_ATTRACT_RADIUS) {
                    entity_set_position(ents[j],
                                        zpl_lerp(p2->x, p[i].x, ITEM_ATTRACT_FORCE*it->delta_time),
                                        zpl_lerp(p2->y, p[i].y, ITEM_ATTRACT_FORCE*it->delta_time));
                }
            }
        }
    }
}

#define ITEM_DROP_PICKUP_TIME 2.5f
#define ITEM_DROP_MERGER_TIME 6.5f

void DropItem(ecs_iter_t *it) {
    Input *in = ecs_field(it, Input, 1);
    Position *p = ecs_field(it, Position, 2);
    Inventory *inv = ecs_field(it, Inventory, 3);

    for (int i = 0; i < it->count; i++) {
        if (!in[i].drop) continue;

        ItemDrop *item = &inv[i].items[in[i].selected_item];

        if (item->quantity <= 0)
            continue;

        uint32_t dropped_count = item->quantity;
        if (in[i].sprint) {
            dropped_count /= 2;
        } else if (in[i].ctrl) {
            dropped_count = dropped_count > 0 ? 1 : 0;
        }

        if (dropped_count == 0)
            continue;

        ecs_entity_t te = item_spawn(item->kind, dropped_count);
        item->quantity -= dropped_count;

        ItemDrop *d = ecs_get_mut(world_ecs(), te, ItemDrop);
        *d = (ItemDrop){
            .kind = item->kind,
            .quantity = dropped_count,
            .merger_time = game_time() + ITEM_DROP_MERGER_TIME,
        };

        Position *ipos = ecs_get_mut(it->world, te, Position);
        *ipos = p[i];

        Velocity *v = ecs_get_mut(it->world, te, Velocity);
        v->x = in[i].mx * 800.0f;
        v->y = in[i].my * 800.0f;

        inv[i].pickup_time = game_time() + ITEM_DROP_PICKUP_TIME;
        in[i].drop = false;

        if (item->quantity == 0) {
            item->kind = 0;
        }
    }
}

void MergeItems(ecs_iter_t *it) {
    Position *p = ecs_field(it, Position, 1);
    ItemDrop *id = ecs_field(it, ItemDrop, 2);

    for (int i = 0; i < it->count; i += 1) {
        ItemDrop *item = &id[i];

        if (item->merger_time < game_time())
            continue;

        size_t ents_count;
        int64_t *ents = world_chunk_query_entities(it->entities[i], &ents_count, 1);

        for (size_t j = 0; j < ents_count; j++) {
            ItemDrop *drop = 0;
            if ((drop = ecs_get_mut_if(it->world, ents[j], ItemDrop))) {
                if (drop->kind != item->kind || (ecs_entity_t)ents[j] == it->entities[i] || drop->quantity == 0 || item->quantity == 0)
                    continue;

                Position const* p2 = ecs_get(it->world, ents[j], Position);

                float dx = p2->x - (p[i].x);
                float dy = p2->y - (p[i].y);
                float range = zpl_sqrt(dx*dx + dy*dy);
                if (range <= ITEM_MERGER_RADIUS) {
                    drop->quantity += item->quantity;
                    item_despawn(it->entities[i]);
                    break;
                }
            }
        }
    }
}

void SwapItems(ecs_iter_t *it) {
    Input *in = ecs_field(it, Input, 1);
    Inventory *inv = ecs_field(it, Inventory, 2);

    for (int i = 0; i < it->count; i++) {
        if (!in[i].swap) continue;

        ItemDrop *to = &inv[i].items[in[i].swap_to];
        ItemDrop *from = &inv[i].items[in[i].swap_from];
        uint16_t to_id = item_find(to->kind);

        if (to == from) {
            // NOTE(zaklaus): do nothing
        } else if (to->kind == from->kind && to->quantity > 0) {
            uint32_t swapped_count = from->quantity;
            if (in[i].sprint) {
                swapped_count /= 2;
            } else if (in[i].ctrl) {
                swapped_count = 1;
            }
            swapped_count = zpl_clamp(swapped_count, 0, item_max_quantity(to_id) - to->quantity);
            to->quantity += swapped_count;
            from->quantity -= swapped_count;

            if (swapped_count == 0) {
                ItemDrop tmp = *to;
                *to = *from;
                *from = tmp;
            }
        } else if ((in[i].ctrl || in[i].sprint) && to->quantity == 0 && from->quantity > 0) {
            // NOTE(zaklaus): item split
            uint32_t split_count = from->quantity / 2;
            if (in[i].ctrl) {
                split_count = 1;
            }
            to->quantity = split_count;
            from->quantity -= split_count;
            to->kind = from->kind;
        } else {
            ItemDrop tmp = *to;
            *to = *from;
            *from = tmp;
        }

        in[i].swap = false;
    }
}

void UseItem(ecs_iter_t *it) {
    Input *in = ecs_field(it, Input, 1);
    Position *p = ecs_field(it, Position, 2);
    Inventory *inv = ecs_field(it, Inventory, 3);

    for (int i = 0; i < it->count; i++) {
        if (!in[i].use && !in[i].num_placements) continue;

        ItemDrop *item = &inv[i].items[in[i].selected_item];
        if (!item || item->quantity <= 0) continue;
        uint16_t item_id = item_find(item->kind);
        item_usage usage = item_get_usage(item_id);

        if (in[i].use && usage > UKIND_END_PLACE)
            item_use(it->world, item, p[i], 0);
        else if (in[i].num_placements > 0 && usage < UKIND_END_PLACE) {
            asset_id ofs = 0;
            if (item_get_place_directional(item_id) && in[i].num_placements >= 2) {
                float p1x = in[i].placements_x[0];
                float p1y = in[i].placements_y[0];
                float p2x = in[i].placements_x[1];
                float p2y = in[i].placements_y[1];
                float sx = zpl_sign0(p2x-p1x);
                float sy = zpl_sign0(p2y-p1y);
                ofs = (sx < 0.0f) ? 1 : 2;
                if (sx == 0.0f) {
                    ofs = (sy < 0.0f) ? 3 : 4;
                }
            } else if(item_get_place_directional(item_id)) {
                // NOTE(zaklaus): ensure we pick the first variant
                ofs = 1;
            }

            for (size_t j = 0; j < in[i].num_placements; j++) {
                Position pos = {.x = in[i].placements_x[j], .y = in[i].placements_y[j]};
                item_use(it->world, item, pos, ofs);
            }

            in[i].num_placements = 0;
        }

        entity_wake(it->entities[i]);
    }
}