[Reverse-engineering] [th05] Aiming to the player

Yes, this only became a dedicated function in TH05, probably due to all
the custom bullet types.

Part of P0086, funded by [Anonymous] and Blue Bolt.

th05/main/player/angle.asm

@@ -0,0 +1,21 @@
+public PLAYER_ANGLE_FROM
+player_angle_from	proc near
+
+@@plus_angle		= byte ptr  4
+@@y		= word ptr  6
+@@x		= word ptr  8
+
+	push	bp
+	mov	bp, sp
+	mov	ax, _player_pos.cur.y
+	sub	ax, [bp+@@y]
+	push	ax
+	mov	ax, _player_pos.cur.x
+	sub	ax, [bp+@@x]
+	push	ax
+	call	iatan2
+	add	al, [bp+@@plus_angle]
+	pop	bp
+	retn	6
+player_angle_from	endp
+	nop

th05/main/player/player.h

@@ -0,0 +1,7 @@
+#include "th04/main/player/player.h"
+
+// Calculates the angle from ([x], [y]) to the current player position, and
+// optionally adds [plus_angle] to the result.
+unsigned char pascal near player_angle_from(
+	Subpixel x, Subpixel y, unsigned char plus_angle = 0
+);