Add anchor points to support manual movement between spaces (#26)

engine/board/movement.asm

@@ -1,5 +1,7 @@
 StepTowardsNextSpace::
 	ld a, [wCurSpaceNextSpace]
+	cp NEXT_SPACE_IS_ANCHOR_POINT
+	jr nc, .move_towards_anchor_point
 	call LoadTempSpaceData
 	ld a, [wTempSpaceXCoord]
 	ld c, a
@@ -27,3 +29,19 @@ StepTowardsNextSpace::
 .done
 	ld [wCurInput], a
 	ret
+
+.move_towards_anchor_point
+	ld c, D_DOWN
+	cp GO_DOWN
+	jr z, .done2
+	ld c, D_UP
+	cp GO_UP
+	jr z, .done2
+	ld c, D_LEFT
+	cp GO_LEFT
+	jr z, .done2
+	ld c, D_RIGHT
+.done2
+	ld a, c
+	ld [wCurInput], a
+	ret

engine/overworld/events.asm

@@ -357,6 +357,32 @@ CheckBoardEvent:
 .board
 	call CheckSpaceEffectsScriptFlag
 	jr z, .no_space_effect
+
+; anchor point handler
+; if wCurSpaceNextSpace is not an anchor point, override any anchor point we pass though
+	ld a, [wCurSpaceNextSpace]
+	cp NEXT_SPACE_IS_ANCHOR_POINT
+	jr c, .next
+	ld a, [wCurMapAnchorEventCount]
+	and a
+	jr z, .next
+; if we have arrived to an anchor point, load its associated next space to wCurSpaceNextSpace right now.
+; don't queue a script so that it happens transparently from the point of view of the player's movement.
+; note that the next space of an anchor point could be another anchor point.
+	ld c, a
+	ld hl, wCurMapAnchorEventsPointer
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld a, [wXCoord]
+	ld d, a
+	ld a, [wYCoord]
+	ld e, a
+	call CheckAndApplyAnchorPoint
+	ret nc ; if we applied an anchor point, we're done here (we're not in a space)
+
+.next
+; space handler
 	ld a, [wPlayerTile]
 	and $f0
 	cp HI_NYBBLE_SPACES