libakgl/src/tilemap.c

/**
 * @file tilemap.c
 * @brief Implements the tilemap subsystem.
 */

#include <string.h>
#include <libgen.h>

#include <SDL3/SDL.h>
#include <SDL3_image/SDL_image.h>
#include <SDL3_mixer/SDL_mixer.h>
#include <jansson.h>

#include <akerror.h>
#include <akstdlib.h>

#include <akgl/tilemap.h>
#include <akgl/actor.h>
#include <akgl/json_helpers.h>
#include <akgl/heap.h>
#include <akgl/registry.h>
#include <akgl/staticstring.h>
#include <akgl/game.h>
#include <akgl/util.h>

akerr_ErrorContext *akgl_get_json_tilemap_property(json_t *obj, char *key, char *type, json_t **dest)
{
    PREPARE_ERROR(errctx);
    json_t *properties = NULL;
    json_t *property = NULL;
    akgl_String *tmpstr = NULL;
    akgl_String *typestr = NULL;
    int i = 0;
    // This is not a generic JSON helper. It assumes we are receiving an object with a 'properties' key
    // inside of it. That key is an array of objects, and each object has a name, type, and value.
    FAIL_ZERO_RETURN(errctx, obj, AKERR_NULLPOINTER, "NULL json obj reference");
    FAIL_ZERO_RETURN(errctx, key, AKERR_NULLPOINTER, "NULL key string");
    ATTEMPT {
	CATCH(errctx, akgl_get_json_array_value(obj, "properties", &properties));
	for (i = 0; i < json_array_size(properties); i++) {
	    CATCH(errctx, akgl_get_json_array_index_object(properties, i, &property));
	    CATCH(errctx, akgl_get_json_string_value(property, "name", &tmpstr));
	    if ( strcmp(tmpstr->data, key) != 0 ) {
		CATCH(errctx, akgl_heap_release_string(tmpstr));
		continue;
	    }
	    CATCH(errctx, akgl_get_json_string_value(property, "type", &typestr));
	    if ( strcmp(typestr->data, type) != 0 ) {
		FAIL_BREAK(errctx, AKERR_TYPE, "Property %s is present but is incorrect type(expected %s got %s)", key, type, (char *)typestr->data);
	    }
	    *dest = property;
	    SUCCEED_RETURN(errctx);
	}
    } CLEANUP {
	if ( tmpstr != NULL ) {
	    IGNORE(akgl_heap_release_string(tmpstr));
	}
	if ( typestr != NULL ) {
	    IGNORE(akgl_heap_release_string(typestr));
	}
    } PROCESS(errctx) {
    } FINISH(errctx, true);

    FAIL_RETURN(errctx, AKERR_KEY, "Property not found in properties map");
}

akerr_ErrorContext *akgl_get_json_properties_string(json_t *obj, char *key, akgl_String **dest)
{
    PREPARE_ERROR(errctx);
    json_t *property;

    PASS(errctx, akgl_get_json_tilemap_property(obj, key, "string", &property));
    PASS(errctx, akgl_heap_next_string(dest));
    PASS(errctx, akgl_string_initialize(*dest, NULL));
    PASS(errctx, akgl_get_json_string_value(property, "value", dest));

    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_get_json_properties_integer(json_t *obj, char *key, int *dest)
{
    PREPARE_ERROR(errctx);
    json_t *property = NULL;
    PASS(errctx, akgl_get_json_tilemap_property(obj, key, "int", &property));
    PASS(errctx, akgl_get_json_integer_value(property, "value", dest));

    SUCCEED_RETURN(errctx);
}

/**
 * @brief Read a Tiled custom property declared as `number`.
 *
 * Tiled writes `float` for a floating-point property, so this matches nothing
 * Tiled produces today -- akgl_get_json_properties_float is the one the loader
 * uses. Kept because a hand-written or older map may still say `number`.
 *
 * @param obj  The Tiled object whose `properties` array to search. Required.
 * @param key  The property name. Required.
 * @param dest Receives the value as a `float`. Not written on any failure path.
 * @return `NULL` on success, otherwise an error context owned by the caller.
 * @throws AKERR_NULLPOINTER If @p obj or @p key is `NULL`.
 * @throws AKERR_KEY If the property is absent, or @p obj has no properties.
 * @throws AKERR_TYPE If the property is not declared `number`, or its `value` is
 *         not numeric.
 * @throws AKGL_ERR_HEAP If the string pool is exhausted.
 */
akerr_ErrorContext *akgl_get_json_properties_number(json_t *obj, char *key, float *dest)
{
    PREPARE_ERROR(errctx);
    json_t *property = NULL;
    PASS(errctx, akgl_get_json_tilemap_property(obj, key, "number", &property));
    PASS(errctx, akgl_get_json_number_value(property, "value", dest));

    SUCCEED_RETURN(errctx);
}

/**
 * @brief Read a Tiled custom property declared as `float`.
 *
 * The spelling Tiled actually writes for a floating-point property. This is how
 * the `scale` on a perspective marker is read.
 *
 * @param obj  The Tiled object whose `properties` array to search. Required.
 * @param key  The property name. Required.
 * @param dest Receives the value. Not written on any failure path.
 * @return `NULL` on success, otherwise an error context owned by the caller.
 * @throws AKERR_NULLPOINTER If @p obj or @p key is `NULL`.
 * @throws AKERR_KEY If the property is absent, or @p obj has no properties.
 * @throws AKERR_TYPE If the property is not declared `float`, or its `value` is
 *         not numeric.
 * @throws AKGL_ERR_HEAP If the string pool is exhausted.
 */
akerr_ErrorContext *akgl_get_json_properties_float(json_t *obj, char *key, float *dest)
{
    PREPARE_ERROR(errctx);
    json_t *property = NULL;
    PASS(errctx, akgl_get_json_tilemap_property(obj, key, "float", &property));
    PASS(errctx, akgl_get_json_number_value(property, "value", dest));

    SUCCEED_RETURN(errctx);
}

/**
 * @brief Read a Tiled custom property declared as `float`, at full precision.
 *
 * Same declared type as akgl_get_json_properties_float, but writing a `double`.
 * The map's physics constants are `double`, which is the reason both exist.
 *
 * @param obj  The Tiled object whose `properties` array to search. Required.
 * @param key  The property name. Required.
 * @param dest Receives the value. Not written on any failure path.
 * @return `NULL` on success, otherwise an error context owned by the caller.
 * @throws AKERR_NULLPOINTER If @p obj or @p key is `NULL`.
 * @throws AKERR_KEY If the property is absent, or @p obj has no properties.
 *         akgl_tilemap_load_physics passes this status to
 *         akgl_get_json_with_default, which turns it into a default of 0.0.
 * @throws AKERR_TYPE If the property is not declared `float`, or its `value` is
 *         not numeric.
 * @throws AKGL_ERR_HEAP If the string pool is exhausted.
 */
akerr_ErrorContext *akgl_get_json_properties_double(json_t *obj, char *key, double *dest)
{
    PREPARE_ERROR(errctx);
    json_t *property = NULL;
    PASS(errctx, akgl_get_json_tilemap_property(obj, key, "float", &property));
    PASS(errctx, akgl_get_json_double_value(property, "value", dest));

    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_load_tilesets_each(json_t *tileset, akgl_Tilemap *dest, int tsidx, akgl_String *dirname)
{
    PREPARE_ERROR(e);
    akgl_String *tmpstr = NULL;
    akgl_String *tmppath = NULL;

    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "columns", &dest->tilesets[tsidx].columns));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "firstgid", &dest->tilesets[tsidx].firstgid));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "imageheight", &dest->tilesets[tsidx].imageheight));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "imagewidth", &dest->tilesets[tsidx].imagewidth));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "margin", &dest->tilesets[tsidx].margin));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "spacing", &dest->tilesets[tsidx].spacing));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "tilecount", &dest->tilesets[tsidx].tilecount));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "tileheight", &dest->tilesets[tsidx].tileheight));
    PASS(e, akgl_get_json_integer_value((json_t *)tileset, "tilewidth", &dest->tilesets[tsidx].tilewidth));

    PASS(e, akgl_get_json_string_value((json_t *)tileset, "name", &tmpstr));
    PASS(e, akgl_heap_next_string(&tmppath));
    ATTEMPT {
	strncpy((char *)&dest->tilesets[tsidx].name,
		(char *)&tmpstr->data,
		AKGL_TILEMAP_MAX_TILESET_NAME_SIZE
	    );

	CATCH(e, akgl_get_json_string_value((json_t *)tileset, "image", &tmpstr));
	CATCH(e, akgl_path_relative((char *)&dirname->data, (char *)&tmpstr->data, tmppath));
	strncpy((char *)&dest->tilesets[tsidx].imagefilename, tmppath->data, AKGL_MAX_STRING_LENGTH);
    } CLEANUP {
	IGNORE(akgl_heap_release_string(tmpstr));
	IGNORE(akgl_heap_release_string(tmppath));
    } PROCESS(e) {
    } FINISH(e, true);

    dest->tilesets[tsidx].texture = IMG_LoadTexture(akgl_renderer->sdl_renderer, (char *)&dest->tilesets[tsidx].imagefilename);
    FAIL_ZERO_RETURN(e, dest->tilesets[tsidx].texture, AKERR_NULLPOINTER, "Failed loading tileset image : %s", SDL_GetError());

    SUCCEED_RETURN(e);
}

akerr_ErrorContext *akgl_tilemap_compute_tileset_offsets(akgl_Tilemap *dest, int tilesetidx)
{
    int x_offset = 0;
    int y_offset = 0;
    int x_col = 0;
    int y_col = 0;
    int j = 0;
    PREPARE_ERROR(errctx);
    /* FIXME: THIS DOES NOT PROPERLY ACCOUNT FOR MARGINS
     * It should be possible to make it work easily I just didn't feel like accounting for them in the
     * initial math.
     */
    /*SDL_Log("Tileset %s has %d rows %d columns",
      dest->tilesets[tilesetidx].name,
      (dest->tilesets[tilesetidx].tilecount / dest->tilesets[tilesetidx].columns),
      dest->tilesets[tilesetidx].columns);*/
    for (j = 0; j <= (dest->tilesets[tilesetidx].tilecount); j++) {
	/*
	 * For a given 8x2 tilemap like this with 10x10 tiles and 0 spacing and 0 margin
	 *
	 * 01234567
	 * 89ABCDEF
	 *
	 * tile 0 would be offset (0,0)
	 * tile 4 would be offset (40,1)
	 * tile 7 would be offset (70,1)
	 * tile 8 would be offset (1,8)
	 * tile C would be offset (40,8)
	 * tile F would be offset (70,8)
	 */
	if ( j >= dest->tilesets[tilesetidx].columns ) {
	    x_col = (j % dest->tilesets[tilesetidx].columns);
	    y_col = (j / dest->tilesets[tilesetidx].columns);
	    x_offset = x_col * (dest->tilesets[tilesetidx].tilewidth + dest->tilesets[tilesetidx].spacing);
	    y_offset = y_col * (dest->tilesets[tilesetidx].tileheight + dest->tilesets[tilesetidx].spacing);
	} else {
	    x_col = j;
	    y_col = 0;
	    x_offset = (j * (dest->tilesets[tilesetidx].tilewidth + dest->tilesets[tilesetidx].spacing));
	    y_offset = dest->tilesets[tilesetidx].spacing;
	}

	dest->tilesets[tilesetidx].tile_offsets[j][0] = x_offset;
	dest->tilesets[tilesetidx].tile_offsets[j][1] = y_offset;
	/* SDL_Log("Tileset %s index (%d, %d) is offset (%d, %d)",
	   dest->tilesets[tilesetidx].name,
	   x_col,
	   y_col,
	   x_offset,
	   y_offset);*/
	// SDL_Log("Processed %d total tiles for tileset", j);
    }
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_load_tilesets(akgl_Tilemap *dest, json_t *root, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "Received NULL tilemap pointer");
    FAIL_ZERO_RETURN(errctx, root, AKERR_NULLPOINTER, "Received NULL json object pointer");

    json_t *tilesets = NULL;
    json_t *jstileset = NULL;
    int i;

    dest->numtilesets = 0;
    ATTEMPT {
	CATCH(errctx, akgl_get_json_array_value(root, "tilesets", &tilesets))
	    for (i = 0; i < json_array_size((json_t *)tilesets); i++) {
		CATCH(errctx, akgl_get_json_array_index_object((json_t *)tilesets, i, &jstileset));
		CATCH(errctx, akgl_tilemap_load_tilesets_each(jstileset, dest, i, dirname));
		CATCH(errctx, akgl_tilemap_compute_tileset_offsets(dest, i));
		dest->numtilesets += 1;
	    }
    } CLEANUP {
    } PROCESS(errctx) {
    } FINISH(errctx, true);

    SUCCEED_RETURN(errctx);
}

/**
 * @brief Turn one Tiled object into a live actor, creating it if it is not already registered.
 *
 * The object's name is the actor's registry key, which is what lets the same
 * actor be placed by more than one object: the first placement creates it and
 * binds the character named in the object's `character` property, and every
 * later one just takes another reference. Either way the object's position,
 * visibility, and layer are copied onto the actor and the object keeps a
 * pointer to it.
 *
 * Not declared in tilemap.h -- reachable only through
 * akgl_tilemap_load_layer_objects.
 *
 * @param curobj         The tilemap object, with its `name`, `x`, `y`, and
 *                       `visible` already read from JSON. Required, unchecked,
 *                       dereferenced at once.
 * @param layerdatavalue The object's JSON, for the custom properties --
 *                       `character` and `state` -- that are not part of Tiled's
 *                       own object fields. Required.
 * @param layerid        The layer this object sits on, copied onto the actor.
 * @param dirname        Directory to resolve paths against. Accepted for
 *                       signature consistency; nothing here uses it.
 * @return `NULL` on success, otherwise an error context owned by the caller.
 * @throws AKERR_KEY If the object's name is empty -- an actor has to be
 *         addressable -- if the `character` or `state` property is absent, or if
 *         the named character is not in #AKGL_REGISTRY_CHARACTER.
 * @throws AKERR_TYPE If `character` is not declared `string` or `state` not
 *         declared `int`.
 * @throws AKERR_NULLPOINTER If akgl_actor_initialize refuses the name.
 * @throws AKGL_ERR_HEAP If the actor or string pool is exhausted.
 *
 * @note An existing actor's `character` and position are overwritten by each
 *       later placement, so two objects naming one actor leave it wherever the
 *       last one put it rather than producing two.
 */
akerr_ErrorContext *akgl_tilemap_load_layer_object_actor(akgl_TilemapObject *curobj, json_t *layerdatavalue, int layerid, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    akgl_String *tmpstr = NULL;
    akgl_Actor *actorobj = NULL;

    curobj->type = AKGL_TILEMAP_OBJECT_TYPE_ACTOR;
    if ( strlen((char *)&curobj->name) == 0 ) {
	FAIL_RETURN(errctx, AKERR_KEY, "Actor in tile object layer cannot have empty name");
    }

    ATTEMPT {
	CATCH(errctx, akgl_heap_next_string(&tmpstr));
	actorobj = SDL_GetPointerProperty(AKGL_REGISTRY_ACTOR, (char *)&curobj->name, NULL);
	if ( actorobj == NULL ) {
	    CATCH(errctx, akgl_heap_next_actor(&actorobj));
	    CATCH(errctx, akgl_actor_initialize((akgl_Actor *)actorobj, (char *)&curobj->name));
	    CATCH(errctx, akgl_get_json_properties_string((json_t *)layerdatavalue, "character", &tmpstr));
	    CATCH(errctx,
		  akgl_actor_set_character(
		      (akgl_Actor *)actorobj,
		      (char *)&tmpstr->data
		      )
		);
	} else {
	    actorobj->refcount += 1;
	}
	CATCH(errctx, akgl_get_json_properties_integer((json_t *)layerdatavalue, "state", &actorobj->state));
    } CLEANUP {
	if ( tmpstr != NULL ) {
	    IGNORE(akgl_heap_release_string(tmpstr));
	}
    } PROCESS(errctx) {
    } FINISH(errctx, true);

    actorobj->layer = layerid;
    actorobj->x = curobj->x;
    actorobj->y = curobj->y;
    actorobj->visible = curobj->visible;
    curobj->actorptr = (akgl_Actor *)actorobj;

    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_load_layer_objects(akgl_Tilemap *dest, json_t *root, int layerid, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    json_t *layerdata = NULL;
    json_t *layerdatavalue = NULL;
    int j;
    int len;
    akgl_TilemapLayer *curlayer = NULL;
    akgl_TilemapObject *curobj = NULL;
    akgl_String *tmpstr = NULL;

    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "NULL destination tilemap reference");
    FAIL_ZERO_RETURN(errctx, root, AKERR_NULLPOINTER, "NULL tilemap root reference");

    PASS(errctx, akgl_get_json_array_value(root, "objects", &layerdata));
    len = json_array_size((json_t *)layerdata);
    curlayer = &dest->layers[layerid];
    for ( j = 0; j < len; j++ ) {
	PASS(errctx, akgl_get_json_array_index_object((json_t *)layerdata, j, &layerdatavalue));
	curobj = &curlayer->objects[j];
	PASS(errctx, akgl_get_json_string_value((json_t *)layerdatavalue, "name", &tmpstr));
	strncpy((char *)curobj->name, tmpstr->data, AKGL_ACTOR_MAX_NAME_LENGTH);
	PASS(errctx, akgl_heap_release_string(tmpstr));
	PASS(errctx, akgl_get_json_number_value((json_t *)layerdatavalue, "x", &curobj->x));
	PASS(errctx, akgl_get_json_number_value((json_t *)layerdatavalue, "y", &curobj->y));
	PASS(errctx, akgl_get_json_boolean_value((json_t *)layerdatavalue, "visible", &curobj->visible));

	PASS(errctx, akgl_get_json_string_value((json_t *)layerdatavalue, "type", &tmpstr));
	if ( strcmp(tmpstr->data, "actor") == 0 ) {
	    PASS(errctx, akgl_tilemap_load_layer_object_actor(curobj, layerdatavalue, layerid, dirname));
	} else if ( strcmp(tmpstr->data, "perspective") == 0 ) {
	    curobj->visible = false;
	    if ( strcmp((char *)curobj->name, "p_foreground") == 0 ) {
		dest->p_foreground_y = curobj->y;
		PASS(errctx, akgl_get_json_integer_value((json_t *)layerdatavalue, "height", &dest->p_foreground_h));
		PASS(errctx, akgl_get_json_properties_float((json_t *)layerdatavalue, "scale", &dest->p_foreground_scale));
	    } else if ( strcmp((char *)curobj->name, "p_vanishing") == 0 ) {
		dest->p_vanishing_y = curobj->y;
		PASS(errctx, akgl_get_json_integer_value((json_t *)layerdatavalue, "height", &dest->p_vanishing_h));
		PASS(errctx, akgl_get_json_properties_float((json_t *)layerdatavalue, "scale", &dest->p_vanishing_scale));
	    }
	}
	layerdatavalue = NULL;
    }

    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_load_layer_tile(akgl_Tilemap *dest, json_t *root, int layerid, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    json_t *layerdata = NULL;
    int j;
    int layerdatalen;

    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "NULL destination tilemap reference");
    FAIL_ZERO_RETURN(errctx, root, AKERR_NULLPOINTER, "NULL tilemap root reference");
    FAIL_ZERO_RETURN(errctx, dirname, AKERR_NULLPOINTER, "dirname");

    ATTEMPT {
	CATCH(errctx, akgl_get_json_integer_value(root, "height", &dest->layers[layerid].height));
	CATCH(errctx, akgl_get_json_integer_value(root, "width", &dest->layers[layerid].width));
	CATCH(errctx, akgl_get_json_array_value(root, "data", &layerdata));
	layerdatalen = (dest->layers[layerid].width * dest->layers[layerid].height);
	if ( layerdatalen >= (AKGL_TILEMAP_MAX_WIDTH * AKGL_TILEMAP_MAX_HEIGHT) ) {
	    FAIL_BREAK(errctx, AKERR_OUTOFBOUNDS, "Map layer exceeds the maximum size");
	}
	for ( j = 0; j < layerdatalen; j++ ) {
	    CATCH(errctx, akgl_get_json_array_index_integer(layerdata, j, &dest->layers[layerid].data[j]));
	}
    } CLEANUP {
    } PROCESS(errctx) {
    } FINISH(errctx, true);

    SUCCEED_RETURN(errctx);
}

/**
 * @brief Load one image layer: upload its image as a single texture.
 *
 * An image layer is one picture rather than a grid, which is what a parallax
 * backdrop wants. The layer's `width` and `height` are taken from the loaded
 * texture rather than from the JSON, so they are always the true pixel size.
 *
 * Not declared in tilemap.h -- reachable only through akgl_tilemap_load_layers.
 *
 * @param dest    The map to load into. Required.
 * @param root    The layer's JSON object. Required.
 * @param layerid Which layer slot to fill. Not bounds-checked.
 * @param dirname Directory to resolve the layer's `image` path against.
 *                Required. Joined with a `/` rather than run through
 *                akgl_path_relative, so unlike a tileset image this path is not
 *                canonicalized and an absolute one will not work.
 * @return `NULL` on success, otherwise an error context owned by the caller.
 * @throws AKERR_NULLPOINTER If @p dest, @p root, or @p dirname is `NULL`.
 * @throws AKERR_KEY If the layer has no `image`.
 * @throws AKERR_TYPE If `image` is not a string.
 * @throws AKGL_ERR_SDL If the image cannot be loaded. The message carries
 *         `SDL_GetError()`.
 * @throws AKGL_ERR_HEAP If the string pool is exhausted.
 *
 * @note The joined path is truncated at
 *       #AKGL_TILEMAP_MAX_TILESET_FILENAME_SIZE without complaint, so an
 *       over-long path fails as a missing file rather than as a length error.
 */
akerr_ErrorContext *akgl_tilemap_load_layer_image(akgl_Tilemap *dest, json_t *root, int layerid, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    akgl_String *tmpstr;
    akgl_String *fpath;

    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "NULL destination tilemap reference");
    FAIL_ZERO_RETURN(errctx, root, AKERR_NULLPOINTER, "NULL tilemap root reference");
    FAIL_ZERO_RETURN(errctx, dirname, AKERR_NULLPOINTER, "dirname");

    ATTEMPT {
	CATCH(errctx, akgl_heap_next_string(&tmpstr));
	CATCH(errctx, akgl_heap_next_string(&fpath));
	CATCH(errctx, akgl_get_json_string_value(root, "image", &tmpstr));

	DISABLE_GCC_WARNING_FORMAT_TRUNCATION
	    snprintf((char *)&fpath->data,
		     AKGL_TILEMAP_MAX_TILESET_FILENAME_SIZE,
		     "%s/%s",
		     dirname->data,
		     tmpstr->data
		);
	RESTORE_GCC_WARNINGS

	    dest->layers[layerid].texture = IMG_LoadTexture(akgl_renderer->sdl_renderer, (char *)fpath->data);
	FAIL_ZERO_BREAK(errctx, dest->layers[layerid].texture, AKGL_ERR_SDL, "%s", SDL_GetError());
	dest->layers[layerid].width = dest->layers[layerid].texture->w;
	dest->layers[layerid].height = dest->layers[layerid].texture->h;
    } CLEANUP {
	IGNORE(akgl_heap_release_string(tmpstr));
	IGNORE(akgl_heap_release_string(fpath));
    } PROCESS(errctx) {
    } FINISH(errctx, true);

    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_load_layers(akgl_Tilemap *dest, json_t *root, akgl_String *dirname)
{
    PREPARE_ERROR(errctx);
    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "akgl_tilemap_load_layers received NULL tilemap pointer");
    FAIL_ZERO_RETURN(errctx, root, AKERR_NULLPOINTER, "akgl_tilemap_load_layers received NULL json object pointer");
    FAIL_ZERO_RETURN(errctx, dirname, AKERR_NULLPOINTER, "dirname");
    json_t *layers = NULL;
    json_t *layer = NULL;
    akgl_String *tmpstr = NULL;
    int i;
    int layerid = 0;
    int tmpint = 0;

    ATTEMPT {
	CATCH(errctx, akgl_get_json_array_value(root, "layers", &layers));
	dest->numlayers = json_array_size((json_t *)layers);
	for ( i = 0; i < dest->numlayers; i++) {
	    if ( i >= AKGL_TILEMAP_MAX_LAYERS ) {
		FAIL_BREAK(errctx, AKERR_OUTOFBOUNDS, "Map exceeds the maximum number of layers");
	    }
	    CATCH(errctx, akgl_get_json_array_index_object((json_t *)layers, i, &layer));
	    CATCH(errctx, akgl_get_json_integer_value((json_t *)layer, "id", &tmpint));
	    CATCH(errctx, akgl_get_json_number_value((json_t *)layer, "opacity", &dest->layers[layerid].opacity));
	    CATCH(errctx, akgl_get_json_boolean_value((json_t *)layer, "visible", &dest->layers[layerid].visible));
	    CATCH(errctx, akgl_get_json_integer_value((json_t *)layer, "id", &dest->layers[layerid].id));
	    CATCH(errctx, akgl_get_json_integer_value((json_t *)layer, "x", &dest->layers[layerid].x));
	    CATCH(errctx, akgl_get_json_integer_value((json_t *)layer, "y", &dest->layers[layerid].y));

	    CATCH(errctx, akgl_get_json_string_value((json_t *)layer, "type", &tmpstr));
	    SDL_Log("Layer %d has type %s", layerid, tmpstr->data);
	    if ( strncmp((char *)tmpstr->data, "objectgroup", strlen((char *)tmpstr->data)) == 0 ) {
		dest->layers[layerid].type = AKGL_TILEMAP_LAYER_TYPE_OBJECTS;
		CATCH(errctx, akgl_tilemap_load_layer_objects((akgl_Tilemap *)dest, (json_t *)layer, layerid, dirname));
	    } else if ( strncmp((char *)tmpstr->data, "tilelayer", strlen((char *)tmpstr->data)) == 0 ) {
		dest->layers[layerid].type = AKGL_TILEMAP_LAYER_TYPE_TILES;
		CATCH(errctx, akgl_tilemap_load_layer_tile((akgl_Tilemap *)dest, (json_t *)layer, layerid, dirname));
	    } else if ( strncmp((char *)tmpstr->data, "imagelayer", strlen((char *)tmpstr->data)) == 0 ) {
		dest->layers[layerid].type = AKGL_TILEMAP_LAYER_TYPE_IMAGE;
		CATCH(errctx, akgl_tilemap_load_layer_image((akgl_Tilemap *)dest, (json_t *)layer, layerid, dirname));
	    }
	    layer = NULL;
	    layerid += 1;
	}
    } CLEANUP {
    } PROCESS(errctx) {
    } FINISH(errctx, true);
    SUCCEED_RETURN(errctx);
}

/**
 * @brief Give the map its own physics backend, if it asked for one.
 *
 * A map with a `physics.model` custom property gets its own backend, configured
 * from `physics.gravity.x`/`.y`/`.z` and `physics.drag.x`/`.y`/`.z`, and
 * `use_own_physics` is set so a caller knows to simulate through it. Each
 * constant defaults to 0.0 when absent, so a map can name a model and override
 * only what it cares about.
 *
 * Absence is the normal case at every level: a map with no properties at all, or
 * with properties but no `physics.model`, uses the game's global backend and
 * this returns success. That is why the AKERR_KEY handlers here are not error
 * paths -- they are the "map did not ask" path.
 *
 * Not declared in tilemap.h -- reachable only through akgl_tilemap_load.
 *
 * @param dest The map to configure. Required in practice; not checked here,
 *             since akgl_tilemap_load has already done so.
 * @param root The map's root JSON object. Required, likewise.
 * @return `NULL` on success -- including when the map declared no physics at
 *         all -- otherwise an error context owned by the caller.
 * @throws AKERR_KEY If `physics.model` names a backend that does not exist.
 * @throws AKERR_TYPE If `physics.model` is not declared `string`, or one of the
 *         six constants is not declared `float`.
 * @throws AKERR_NULLPOINTER If akgl_physics_factory refuses its arguments.
 * @throws AKGL_ERR_HEAP If the string pool is exhausted.
 */
akerr_ErrorContext *akgl_tilemap_load_physics(akgl_Tilemap *dest, json_t *root)
{
    PREPARE_ERROR(e);
    json_t *props = NULL;
    akgl_String *tmpval = NULL;
    double defzero = 0.0;

    ATTEMPT {
	CATCH(e, akgl_heap_next_string(&tmpval));
	CATCH(e, akgl_get_json_array_value((json_t *)root, "properties", &props));
    } CLEANUP {
	IGNORE(akgl_heap_release_string(tmpval));
    } PROCESS(e) {
    } HANDLE(e, AKERR_KEY) {
	// Map has no properties, do nothing
	SDL_Log("Map has no properties");
	SUCCEED_RETURN(e);
    } FINISH(e, true);

    ATTEMPT {
	CATCH(e, akgl_heap_next_string(&tmpval));
	CATCH(e, akgl_get_json_properties_string(
		  root,
		  "physics.model",
		  &tmpval
		  )
	    );
	PASS(e, akgl_physics_factory(&dest->physics, tmpval));
	dest->use_own_physics = true;

	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.gravity.x", &dest->physics.gravity_x
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.gravity_x,
		  sizeof(double)));
	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.gravity.y", &dest->physics.gravity_y
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.gravity_y,
		  sizeof(double)));
	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.gravity.z", &dest->physics.gravity_z
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.gravity_z,
		  sizeof(double)));
	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.drag.x", &dest->physics.drag_x
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.drag_x,
		  sizeof(double)));
	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.drag.y", &dest->physics.drag_y
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.drag_y,
		  sizeof(double)));
	CATCH(e, akgl_get_json_with_default(
		  akgl_get_json_properties_double(
		      root, "physics.drag.z", &dest->physics.drag_z
		      ),
		  (void *)&defzero,
		  (void *)&dest->physics.drag_z,
		  sizeof(double)));
    } CLEANUP {
	IGNORE(akgl_heap_release_string(tmpval));
    } PROCESS(e) {
    } HANDLE(e, AKERR_KEY) {
	SDL_Log("Map uses game physics");
    } FINISH(e, true);

    SUCCEED_RETURN(e);
}

akerr_ErrorContext *akgl_tilemap_load(char *fname, akgl_Tilemap *dest)
{
    PREPARE_ERROR(errctx);
    json_t *json = NULL;
    //akgl_String *tmpstr = NULL;
    json_error_t error;
    akgl_String *dirnamestr = NULL;

    FAIL_ZERO_RETURN(errctx, fname, AKERR_NULLPOINTER, "load_tilemap received null filename");
    FAIL_ZERO_RETURN(errctx, dest, AKERR_NULLPOINTER, "load_tilemap received null tilemap");

    memset(dest, 0x00, sizeof(akgl_Tilemap));
    dest->p_foreground_scale = 1.0;
    dest->p_vanishing_scale = 1.0;

    PASS(errctx, akgl_heap_next_string(&dirnamestr));
    ATTEMPT {
	//CATCH(errctx, akgl_heap_next_string(&tmpstr));
	//CATCH(errctx, akgl_string_initialize(tmpstr, NULL));
	//SDL_snprintf(tmpstr->data, AKGL_MAX_STRING_LENGTH, "%s%s", SDL_GetBasePath(), fname);
	CATCH(errctx, aksl_realpath(fname, (char *)&dirnamestr->data, sizeof(dirnamestr->data)));
	dirname((char *)&dirnamestr->data);

	json = json_load_file(fname, 0, &error);
	FAIL_ZERO_BREAK(
	    errctx,
	    json,
	    AKERR_NULLPOINTER,
	    "Error while loading tilemap from %s on line %d: %s-",
	    fname,
	    error.line,
	    error.text
	    );
	CATCH(errctx, akgl_tilemap_load_physics(dest, json));
	CATCH(errctx, akgl_get_json_integer_value((json_t *)json, "tileheight", &dest->tileheight));
	CATCH(errctx, akgl_get_json_integer_value((json_t *)json, "tilewidth", &dest->tilewidth));
	CATCH(errctx, akgl_get_json_integer_value((json_t *)json, "height", &dest->height));
	CATCH(errctx, akgl_get_json_integer_value((json_t *)json, "width", &dest->width));

	dest->orientation = 0;
	if ( (dest->width * dest->height) >= (AKGL_TILEMAP_MAX_WIDTH * AKGL_TILEMAP_MAX_HEIGHT) ) {
	    FAIL_RETURN(errctx, AKERR_OUTOFBOUNDS, "Map exceeds the maximum size");
	}

	CATCH(errctx, akgl_tilemap_load_layers((akgl_Tilemap *)dest, (json_t *)json, dirnamestr));
	CATCH(errctx, akgl_tilemap_load_tilesets((akgl_Tilemap *)dest, (json_t *)json, dirnamestr));

	if ( dest->p_foreground_y && dest->p_vanishing_y ) {
	    // How much bigger is the foreground vs the vanishing point?
	    // if vanishing is height 16, and foreground is height 32, that is a 2x scale difference
	    /* dest->p_scale = ((float)dest->p_foreground_h / (float)dest->p_vanishing_h); */
	    /* SDL_Log("Map perspective scale is (%d/%d) = %f", dest->p_foreground_h, dest->p_vanishing_h, dest->p_scale); */
	    // Sprites are scale N (default 1.0) at the foreground, so how much do we need to
	    // scale them for every pixel above foreground_y before they reach vanishing_y?
	    // If vanishing is at 320 and foreground is at 640, that is a 320 line difference
	    // If our scaling rate is 2x, then our rate is (((N=1.0) / (640 - 320)) / (dest->p_scale = 2)), or
	    // 0.0066% scale per pixel.
	    dest->p_rate = ((dest->p_foreground_scale - dest->p_vanishing_scale) / (dest->p_foreground_y - dest->p_vanishing_y));
	    SDL_Log("Map perspective rate is %f", dest->p_rate);
	}
    } CLEANUP {
	//IGNORE(akgl_heap_release_string(tmpstr));
	// The map is built entirely out of copies -- layer data, tileset
	// geometry, object names -- so the document is dead the moment the
	// loaders above return, whether they succeeded or not. It is also the
	// largest of the four: a map's JSON is the size of its layer data.
	if ( json != NULL ) {
	    json_decref(json);
	    json = NULL;
	}
    } PROCESS(errctx) {
    } FINISH(errctx, true);
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_draw(akgl_Tilemap *map, SDL_FRect *viewport, int layeridx)
{
    PREPARE_ERROR(errctx);
    SDL_FRect dest = {.x = 0, .y = 0, .w = 0, .h = 0};;
    SDL_FRect src = {.x = 0, .y = 0, .w = 0, .h = 0};
    int start_x = 0;
    int start_y = 0;
    int end_x = 0;
    int end_y = 0;
    int yidx = 0;
    int xidx = 0;
    int tilesetidx = 0;
    int tilenum = 0;
    int offset = 0;
    /*
     * Render every tile in the map that partially intersects the viewport
     *
     * For an 8x2 tilemap with 16 pixel square tiles like this
     *
     * 01234567
     * 89ABCDEF
     *
     * With a viewport of (x=20, y=8, w=90, y=20), we would render:
     *
     * 123456
     * 9ABCDE
     *
     * 0 and 8 would not be rendered. 1, 9, 6, and E would be partially rendered at their corner.
     * 2,3,4,5 and A,B,C,D would be partially rendered with a slice from their center.
     */
    FAIL_ZERO_RETURN(errctx, map, AKERR_NULLPOINTER, "akgl_tilemap_draw received NULL pointer to tilemap");
    FAIL_ZERO_RETURN(errctx, viewport, AKERR_NULLPOINTER, "akgl_tilemap_draw received NULL pointer to viewport");

    /* Only try to render the stuff that is partially within the viewport */

    start_x = viewport->x / map->tilewidth;
    start_y = viewport->y / map->tileheight;
    end_x = (viewport->x + viewport->w) / map->tilewidth;
    end_y = (viewport->y + viewport->h) / map->tileheight;
    if ( end_x > map->width ) {
	end_x = map->width;
    }
    if ( end_y > map->height ) {
	end_y = map->height;
    }

    /*SDL_Log("Rendering map into viewport from (%d, %d) to (%d, %d)",
      start_x, start_y, end_x, end_y);*/

    if ( map->layers[layeridx].type == AKGL_TILEMAP_LAYER_TYPE_IMAGE ) {
	dest.x = 0;
	dest.y = 0;
	src.w = map->layers[layeridx].width;
	src.h = map->layers[layeridx].height;
	dest.w = map->layers[layeridx].width;
	dest.h = map->layers[layeridx].height;
	PASS(errctx, akgl_renderer->draw_texture(akgl_renderer, map->layers[layeridx].texture, &src, &dest, 0, NULL, SDL_FLIP_NONE));
	SUCCEED_RETURN(errctx);
    }

    dest.x = 0;
    dest.y = 0;
    dest.w = map->tilewidth;
    dest.h = map->tileheight;
    for ( yidx = start_y; yidx < end_y; yidx++ ) {
	dest.x = 0;
	for ( xidx = start_x; xidx < end_x; xidx++ ) {
	    if ( yidx == 0 ) {
		offset = xidx;
	    } else {
		offset = xidx + (yidx * (map->width));
	    }
	    tilenum = map->layers[layeridx].data[offset];
	    // FIXME: This is probably not very efficient. Need a better way to look up
	    // tile offsets within the tilesets by their tile ID.
	    for ( tilesetidx = 0; tilesetidx < map->numtilesets ; tilesetidx++ ) {
		if ( map->tilesets[tilesetidx].firstgid <= tilenum &&
		     (map->tilesets[tilesetidx].firstgid + map->tilesets[tilesetidx].tilecount) >= tilenum ) {
		    // Render this tile to the correct screen position
		    // FIXME: These conditionals are probably not very efficient. Need a better way of getting
		    // the intersection of this tile with the viewport and rendering only that portion.
		    if ( xidx == 0 ) {
			src.x += (int)viewport->x % map->tilewidth;
			src.w = map->tilewidth - ((int)viewport->x % map->tilewidth);
		    } else {
			src.x = map->tilesets[tilesetidx].tile_offsets[tilenum - map->tilesets[tilesetidx].firstgid][0];
			src.w = map->tilewidth;
		    }
		    if ( yidx == 0 ) {
			src.y += (int)viewport->y % map->tileheight;
			src.h = map->tileheight - ((int)viewport->y % map->tileheight);
		    } else {
			src.y = map->tilesets[tilesetidx].tile_offsets[tilenum - map->tilesets[tilesetidx].firstgid][1];
			src.h = map->tileheight;
		    }
		    /*SDL_Log("Blitting tile #%d (local tileset id %d from offset %d) from map layer %d map (x=%d,y=%d) tileset %d (x=%f,y=%f,w=%f,h=%f) to (x=%f,y=%f,w=%f,h=%f)",
		      tilenum,
		      (tilenum - map->tilesets[tilesetidx].firstgid),
		      offset,
		      layeridx,
		      xidx,
		      yidx,
		      tilesetidx,
		      src.x,
		      src.y,
		      src.w,
		      src.h,
		      dest.x,
		      dest.y,
		      dest.w,
		      dest.h);*/
		    PASS(errctx, akgl_renderer->draw_texture(akgl_renderer, map->tilesets[tilesetidx].texture, &src, &dest, 0, NULL, SDL_FLIP_NONE));
		}
	    }
	    dest.x += map->tilewidth;
	}
	dest.y += map->tileheight;
    }
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext *akgl_tilemap_draw_tileset(akgl_Tilemap *map, int tilesetidx)
{
    PREPARE_ERROR(errctx);
    SDL_FRect dest;
    SDL_FRect src;
    int tilenum = 0;
    /*
     * Render every tile in a tileset to the default renderer
     * (this is a debugging tool that shows that the recorded tile offsets are correct,
     * by proving that we can reconstruct the original tileset image)
     */

    FAIL_ZERO_RETURN(errctx, map, AKERR_NULLPOINTER, "akgl_tilemap_draw_tileset received NULL pointer to tilemap");
    FAIL_NONZERO_RETURN(errctx, (tilesetidx >= map->numtilesets), AKERR_OUTOFBOUNDS, "akgl_tilemap_draw_tileset received a tileset index out of bounds");

    for ( tilenum = 0; tilenum < map->tilesets[tilesetidx].tilecount; tilenum++) {
	// Render this tile to the correct screen position
	// FIXME: These conditionals are probably not very efficient. Need a better way of getting
	// the intersection of this tile with the viewport and rendering only that portion.
	src.x = map->tilesets[tilesetidx].tile_offsets[tilenum][0];
	src.y = map->tilesets[tilesetidx].tile_offsets[tilenum][1];
	src.w = map->tilewidth;
	src.h = map->tileheight;
	dest.x = tilenum * map->tilewidth;
	if ( tilenum >= map->tilesets[tilesetidx].columns ) {
	    dest.x = (tilenum % (map->tilesets[tilesetidx].columns)) * map->tilewidth;
	}
	if ( tilenum >= (map->tilesets[tilesetidx].columns) ) {
	    dest.y = (tilenum / (map->tilesets[tilesetidx].columns)) * map->tileheight;
	} else {
	    dest.y = 0;
	}
	dest.w = src.w;
	dest.h = src.h;
	/*SDL_Log("Blitting tile #%d from map tileset %d (x=%f,y=%f,w=%f,h=%f) to (x=%f,y=%f,w=%f,h=%f)",
	  tilenum,
	  tilesetidx,
	  src.x,
	  src.y,
	  src.w,
	  src.h,
	  dest.x,
	  dest.y,
	  dest.w,
	  dest.h);*/
	PASS(errctx, akgl_renderer->draw_texture(akgl_renderer, map->tilesets[tilesetidx].texture, &src, &dest, 0, NULL, SDL_FLIP_NONE));
    }
    SUCCEED_RETURN(errctx);
}

akerr_ErrorContext AKERR_NOIGNORE *akgl_tilemap_scale_actor(akgl_Tilemap *map, akgl_Actor *actor)
{
    PREPARE_ERROR(e);

    FAIL_ZERO_RETURN(e, map, AKERR_NULLPOINTER, "NULL map");
    FAIL_ZERO_RETURN(e, actor, AKERR_NULLPOINTER, "NULL actor");

    if ( actor->y <= map->p_vanishing_y ) {
	actor->scale = map->p_vanishing_scale;
    } else if ( actor->y >= map->p_foreground_y ) {
	actor->scale = map->p_foreground_scale;
    } else {
	actor->scale = map->p_foreground_scale - (map->p_rate * (map->p_foreground_y - actor->y));
    }
    SUCCEED_RETURN(e);
}

akerr_ErrorContext AKERR_NOIGNORE *akgl_tilemap_release(akgl_Tilemap *dest)
{
    // Release all tileset textures
    // Release all image layer textures
    // Memset to zero
    PREPARE_ERROR(e);
    FAIL_ZERO_RETURN(e, dest, AKERR_NULLPOINTER, "NULL map");
    int i = 0;
    for ( i = 0; i < AKGL_TILEMAP_MAX_TILESETS; i++ ) {
	if ( dest->tilesets[i].texture != NULL ) {
	    SDL_DestroyTexture(dest->tilesets[i].texture);
	}
    }
    for ( i = 0; i < AKGL_TILEMAP_MAX_LAYERS; i++ ) {
	if ( dest->layers[i].texture != NULL ) {
	    SDL_DestroyTexture(dest->tilesets[i].texture);
	}
    }
    SUCCEED_RETURN(e);
}