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+/* SPDX-License-Identifier: MIT */
+/*
+ * konrpg.h
+ *
+ * Copyright (c) 2026 KonAki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef KONRPG_H
+#define KONRPG_H
+
+#include "kontile.h"
+
+/*** directions ***/
+
+/* the order of the rows in an RPG Maker character sheet */
+typedef enum kon_dir {
+	KON_DIR_DOWN,
+	KON_DIR_LEFT,
+	KON_DIR_RIGHT,
+	KON_DIR_UP
+} kon_dir_t;
+
+/* one tile in that direction, y grows downwards */
+void kon_dirDelta(kon_dir_t dir, int *dx, int *dy);
+kon_dir_t kon_dirOpposite(kon_dir_t dir);
+
+/*** actors ***/
+
+/* something that walks a tile at a time. column, row is the tile it is on, or heading for while it moves.
+   the game picks the direction every frame, kon_actorWalk starts a step when it is standing still and kon_actorUpdate moves it along */
+typedef struct kon_actor {
+	int column, row;
+	int fromColumn, fromRow;
+	kon_dir_t facing;
+	int moving;
+	float progress; /* 0 to 1 along the current step */
+	float speed; /* tiles a second */
+
+	/* private */
+	float carry;
+} kon_actor_t;
+
+/* return non-zero if something other than the tilemap stands in the way of a step onto column, row */
+typedef int (*kon_blockFn)(int column, int row, void *user);
+
+void kon_actorInit(kon_actor_t *actor, int column, int row, kon_dir_t facing);
+
+/* turns to face dir, then starts a step if the tile ahead is inside the map, not solid (see kon_tilemapBoxHits for solid) and not
+   blocked by the callback, which may be NULL. does nothing but turn while a step is going. returns 1 if a step started */
+int kon_actorWalk(kon_actor_t *actor, const kon_tilemap_t *map, const uint8_t *solid, int solidCount, kon_dir_t dir, kon_blockFn blocked, void *user);
+
+/* returns 1 on the frame the actor arrives on a tile. time left over at the end of a step is kept for the next one,
+   so holding a direction walks at exactly speed at any frame rate */
+int kon_actorUpdate(kon_actor_t *actor, float dt);
+
+/* where the actor's top left is in map pixels, in between tiles while it moves */
+void kon_actorPixel(const kon_actor_t *actor, const kon_tilemap_t *map, float *x, float *y);
+
+/* the tile the actor is looking at, the one it is on while it moves */
+void kon_actorFront(const kon_actor_t *actor, int *column, int *row);
+
+/*** events ***/
+
+typedef enum kon_trigger {
+	KON_TRIGGER_TALK, /* the actor faces it and presses the action key */
+	KON_TRIGGER_TOUCH, /* the actor walks into it */
+	KON_TRIGGER_STEP /* the actor arrives on it */
+} kon_trigger_t;
+
+/* a thing on the map the game reacts to. id means whatever the game wants, a switch into its own script, a door, a chest.
+   blocks makes it solid like a person or a rock. to move one just change its column and row */
+typedef struct kon_tileEvent {
+	int column, row;
+	kon_trigger_t trigger;
+	int id;
+	int blocks;
+} kon_tileEvent_t;
+
+/* index of the first event on the tile with that trigger, or -1. trigger -1 matches any */
+int kon_eventAt(const kon_tileEvent_t *events, int count, int column, int row, int trigger);
+
+/* 1 if a blocking event is on the tile, for kon_actorWalk. user is a kon_eventList_t */
+typedef struct kon_eventList { const kon_tileEvent_t *events; int count; } kon_eventList_t;
+int kon_eventBlocks(int column, int row, void *user);
+
+#endif