From b4a64324fe25355dce0eac19ee5a0fb27d8d3b2a Mon Sep 17 00:00:00 2001
From: nmlgc <nmlgc@nmlgc.net>
Date: Sun, 24 Oct 2021 19:31:54 +0200
Subject: [PATCH] [Decompilation] [th01] Missiles: Unput/update/render function
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

And that's why these feel so awful in-game: Interlaced rendering, and
an unfair 46×46 hitbox around Reimu's center point.

Part of P0165, funded by Ember2528.
---
 th01/main/bullet/missile.cpp | 168 +++++++++++++++++
 th01/main/bullet/missile.hpp |   3 +
 th01/main_32_.cpp            |   1 +
 th01_reiiden.asm             | 351 +----------------------------------
 4 files changed, 179 insertions(+), 344 deletions(-)
 create mode 100644 th01/main/bullet/missile.cpp

diff --git a/th01/main/bullet/missile.cpp b/th01/main/bullet/missile.cpp
new file mode 100644
index 00000000..6df6eb68
--- /dev/null
+++ b/th01/main/bullet/missile.cpp
@@ -0,0 +1,168 @@
+extern "C" {
+#include "planar.h"
+#include "th01/math/overlap.hpp"
+#include "th01/hardware/egc.h"
+#include "th01/hardware/input.hpp"
+#include "th01/snd/mdrv2.h"
+#include "th01/formats/ptn.hpp"
+}
+#include "th01/main/vars.hpp"
+#include "th01/main/bullet/missile.hpp"
+
+// Missiles are blitted to unaligned X positions (and are, in fact, the only
+// 16×16 .PTN entity where this is the case), so a missile sprite is likely
+// to cover two 16-pixel words. Since the left coordinate is rounded down to
+// the previous multiple of 16, the unblitting width therefore has to be
+// doubled.
+// … Except that it doesn't have to, because egc_copy_rect_1_to_0_16() already
+// ceils the unblitted width to the next multiple of 16. Which makes this
+// addition just as unnecessary as the _word_w() wrapper.
+#define sloppy_unput(missiles, i) { \
+	egc_copy_rect_1_to_0_16_word_w( \
+		(missiles).prev_left[i].to_pixel(), \
+		(missiles).prev_top[i].to_pixel(), \
+		(15 + MISSILE_W), \
+		MISSILE_H \
+	); \
+}
+
+#define in_current_interlace_field(i) \
+	((i % 2) == (frame_rand & 1))
+
+// Calculates the current [ptn_id] and [quarter] for the missile at the given
+// index.
+// TODO: Should be turned into a class method once it can be part of this
+// translation unit.
+void ptn_cel_for(CMissiles& that, int i, main_ptn_id_t& ptn_id, int& quarter);
+
+void CMissiles::unput_update_render(void)
+{
+	int i;
+
+	// Unput/update/explode
+	for(i = 0; i < MISSILE_COUNT; i++) {
+		if(flag[i] == MF_FREE) {
+			continue;
+		}
+		if(in_current_interlace_field(i) && (prev_left[i].v != MISSILE_NEW)) {
+			sloppy_unput(*this, i);
+		}
+		if(flag[i] == MF_MOVING) {
+			cur_left[i].v += velocity_x[i].v;
+			cur_top[i].v += velocity_y[i].v;
+
+			if(!overlap_xy_lrtb_le_ge(
+				cur_left[i].to_pixel(),
+				cur_top[i].to_pixel(),
+				MISSILE_LEFT_MIN,
+				MISSILE_TOP_MIN,
+				MISSILE_LEFT_MAX,
+				MISSILE_TOP_MAX
+			)) {
+				flag[i] = MF_HIT;
+				sloppy_unput(*this, i);
+
+				if(cur_left[i].to_pixel() < MISSILE_LEFT_MIN) {
+					prev_left[i].v = to_sp(MISSILE_LEFT_MIN);
+				} else if(cur_left[i].to_pixel() > MISSILE_LEFT_MAX) {
+					prev_left[i].v = to_sp(MISSILE_LEFT_MAX);
+				}
+				if(cur_top[i].to_pixel() < MISSILE_TOP_MIN) {
+					prev_top[i].v = to_sp(MISSILE_TOP_MIN);
+				} else if(cur_top[i].to_pixel() > MISSILE_TOP_MAX) {
+					prev_top[i].v = to_sp(PLAYFIELD_BOTTOM - (MISSILE_H / 2));
+				}
+			}
+		} else {
+			if(in_current_interlace_field(i)) {
+				static_cast<int8_t>(flag[i])++;
+			}
+			if(flag[i] > MF_HIT_last) {
+				flag[i] = MF_FREE;
+				sloppy_unput(*this, i);
+				mdrv2_se_play(7);
+			}
+		}
+	}
+
+	// Render
+	for(i = 0; i < MISSILE_COUNT; i++) {
+		if((flag[i] == MF_FREE) || !in_current_interlace_field(i)) {
+			continue;
+		} else if(flag[i] == MF_MOVING) {
+			main_ptn_id_t ptn_id;
+			int quarter;
+
+			/* TODO: Replace with the decompiled calls
+			 * 	ptn_cel_for(i, ptn_id, quarter);
+			 * 	ptn_put_quarter(
+			 * 		cur_left[i].to_pixel(), cur_top[i].to_pixel(), ptn_id, quarter
+			 * 	);
+			 * once ptn_cel_for() is part of this translation unit */
+			__asm {
+				push	ss;
+				lea 	ax, quarter;
+				push	ax
+				push	ss;
+				lea 	ax, ptn_id;
+				push	ax
+				db  	0x56;	// PUSH SI
+				db  	0x66, 0xFF, 0x76, 0x06;	// PUSH LARGE [this]
+				push	cs;
+				call	near ptr ptn_cel_for;
+				push	quarter;
+				push 	ptn_id;
+			}
+			_AX = cur_top[i].to_pixel();
+			__asm {
+				push	ax;
+			}
+			_AX = ((Subpixel *)(
+				(uint8_t  __seg *)(_ES) +
+				(uint8_t __near *)(_BX) +
+				(uint16_t)&(((CMissiles __near *)0)->cur_left)
+			))->to_pixel();
+			__asm {
+				push	ax;
+				call	far ptr ptn_put_quarter
+				add 	sp, 22
+			}
+			prev_left[i] = cur_left[i];
+			prev_top[i] = cur_top[i];
+		} else { // >= MF_HIT
+			ptn_put_quarter(
+				prev_left[i].to_pixel(),
+				prev_top[i].to_pixel(),
+				(ptn_id_base + MISSILE_HIT_IMAGE),
+				(flag[i] - MF_HIT)
+			);
+		}
+	}
+
+	// Collision detection
+	if(player_invincible) {
+		return;
+	}
+	for(i = 0; i < MISSILE_COUNT; i++) {
+		if(flag[i] == MF_FREE) {
+			continue;
+		}
+
+		// 46×46 pixels around the player's center point
+		enum {
+			HITBOX_OFFSET_LEFT = (-(MISSILE_W / 2)),
+			HITBOX_OFFSET_RIGHT = ((PLAYER_W / 2) + (MISSILE_W / 2)),
+			HITBOX_OFFSET_TOP = (-(MISSILE_H / 2)),
+			HITBOX_OFFSET_BOTTOM = (PLAYER_H)
+		};
+		if(
+			(cur_left[i].to_pixel() > (player_left + HITBOX_OFFSET_LEFT)) &&
+			(cur_left[i].to_pixel() < (player_left + HITBOX_OFFSET_RIGHT)) &&
+			(cur_top[i].to_pixel() < (player_top + HITBOX_OFFSET_BOTTOM)) &&
+			(cur_top[i].to_pixel() > (player_top + HITBOX_OFFSET_TOP))
+		) {
+			done = true;
+			return;
+		}
+	}
+}
diff --git a/th01/main/bullet/missile.hpp b/th01/main/bullet/missile.hpp
index 35e5c543..9896e058 100644
--- a/th01/main/bullet/missile.hpp
+++ b/th01/main/bullet/missile.hpp
@@ -40,6 +40,9 @@ class CMissiles {
 	int8_t unknown[MISSILE_COUNT];
 	uint8_t ptn_id_base; // main_ptn_id_t. Very bold to limit this to 8 bits!
 	missile_flag_t flag[MISSILE_COUNT];
+
+public:
+	void unput_update_render(void);
 };
 
 extern CMissiles Missiles;
diff --git a/th01/main_32_.cpp b/th01/main_32_.cpp
index 76bd5ae4..9d746d1a 100644
--- a/th01/main_32_.cpp
+++ b/th01/main_32_.cpp
@@ -8,5 +8,6 @@ extern "C" {
 #include "th01/main/player/player.hpp"
 }
 
+#include "th01/main/bullet/missile.cpp"
 #include "th01/main/player/bomb_d_f.cpp"
 #include "th01/main/particle.cpp"
diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index 5122d68e..278367b1 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -6004,7 +6004,6 @@ main_27_TEXT	segment	byte public 'CODE' use16
 	extern _ptn_unput_8:proc
 	extern _ptn_put_8:proc
 	extern _ptn_put_quarter_8:proc
-	extern _ptn_put_quarter:proc
 	extern _player_unput_update_render:proc
 OR_NONE = 0
 	extern @orb_player_hittest$qi:proc
@@ -6694,7 +6693,7 @@ var_4		= word ptr -4
 		push	si
 		mov	ax, word ptr _yuugenmagan_invincibility_flash_colors
 		mov	[bp+@@invincibility_flash_colors], ax
-		call	sub_21F19 c, offset _Missiles, ds
+		call	@CMissiles@unput_update_render$qv c, offset _Missiles, ds
 		cmp	_boss_phase, 0
 		jnz	loc_1BEC0
 		cmp	_yuugenmagan_initial_hp_rendered, 0
@@ -12924,7 +12923,7 @@ sub_1FA7B	proc far
 		push	di
 		mov	ax, word ptr _mima_invincibility_flash_colors
 		mov	[bp+@@invincibility_flash_colors], ax
-		call	sub_21F19 stdcall, offset _Missiles, ds
+		call	@CMissiles@unput_update_render$qv stdcall, offset _Missiles, ds
 		call	@particles_unput_update_render$q17particle_origin_ti stdcall, large PO_TOP_RIGHT or (V_WHITE shl 16)
 		add	sp, 8
 		cmp	_boss_phase, 0
@@ -14393,22 +14392,10 @@ main_32__TEXT	segment	byte public 'CODE' use16
 		;org 4
 		assume es:nothing, ss:nothing, ds:_DATA, fs:nothing, gs:nothing
 
-MISSILE_W = 16
-MISSILE_H = 16
-MISSILE_LEFT_MIN = PLAYFIELD_LEFT
-MISSILE_TOP_MIN = PLAYFIELD_TOP
-MISSILE_LEFT_MAX = (PLAYFIELD_RIGHT - MISSILE_W)
-MISSILE_TOP_MAX = (PLAYFIELD_BOTTOM - 1)
-
 MISSILE_NEW = -1
 
-MISSILE_HIT_CELS = 2
-MISSILE_HIT_IMAGE = 4
-
 MF_FREE = 0
 MF_MOVING = 1
-MF_HIT = 2
-MF_HIT_last = (MF_HIT + MISSILE_HIT_CELS - 1)
 
 ; =============== S U B	R O U T	I N E =======================================
 
@@ -14490,8 +14477,8 @@ sub_21C0D	endp
 ; =============== S U B	R O U T	I N E =======================================
 
 ; Attributes: bp-based frame
-
-sub_21CA3	proc far
+public @ptn_cel_for$qm9CMissilesim13main_ptn_id_tmi
+@ptn_cel_for$qm9CMissilesim13main_ptn_id_tmi	proc far
 
 var_A		= word ptr -0Ah
 var_8		= qword	ptr -8
@@ -14771,7 +14758,7 @@ loc_21EF6:
 		pop	si
 		leave
 		retf
-sub_21CA3	endp
+@ptn_cel_for$qm9CMissilesim13main_ptn_id_tmi	endp
 
 
 ; =============== S U B	R O U T	I N E =======================================
@@ -14801,331 +14788,7 @@ loc_21F12:
 		retf
 sub_21EFF	endp
 
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_21F19	proc far
-
-var_4		= word ptr -4
-var_2		= word ptr -2
-@@this		= dword	ptr  6
-
-		enter	4, 0
-		push	si
-		xor	si, si
-		jmp	loc_220EA
-; ---------------------------------------------------------------------------
-
-loc_21F23:
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_FREE
-		jz	loc_220E9
-		mov	ax, si
-		mov	bx, 2
-		cwd
-		idiv	bx
-		movsx	eax, dx
-		mov	edx, _frame_rand
-		and	edx, 1
-		cmp	eax, edx
-		jnz	short loc_21F7D
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		cmp	es:[bx+CMissiles.MISSILE_prev_left], MISSILE_NEW
-		jz	short loc_21F7D
-		push	(16 shl 16) or 32
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_top]
-		sar	ax, 4
-		push	ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_left]
-		sar	ax, 4
-		push	ax
-		call	_egc_copy_rect_1_to_0_16
-		add	sp, 8
-
-loc_21F7D:
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_MOVING
-		jnz	loc_2207D
-		mov	ax, si
-		add	ax, ax
-		mov	bx, word ptr [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_velocity_x]
-		add	es:[bx+CMissiles.MISSILE_cur_left], ax
-		mov	ax, es:[bx+CMissiles.MISSILE_velocity_y]
-		add	es:[bx+CMissiles.MISSILE_cur_top], ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		or	ax, ax
-		jl	short loc_21FD5
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		cmp	ax, MISSILE_LEFT_MAX
-		jg	short loc_21FD5
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, MISSILE_TOP_MIN
-		jl	short loc_21FD5
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, MISSILE_TOP_MAX
-		jle	loc_220E9
-
-loc_21FD5:
-		les	bx, [bp+@@this]
-		add	bx, si
-		mov	es:[bx+CMissiles.MISSILE_flag], MF_HIT
-		push	(16 shl 16) or 32
-		mov	ax, si
-		add	ax, ax
-		mov	bx, word ptr [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_top]
-		sar	ax, 4
-		push	ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_left]
-		sar	ax, 4
-		push	ax
-		call	_egc_copy_rect_1_to_0_16
-		add	sp, 8
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		or	ax, ax
-		jge	short loc_22025
-		mov	es:[bx+CMissiles.MISSILE_prev_left], (MISSILE_LEFT_MIN shl 4)
-		jmp	short loc_22040
-; ---------------------------------------------------------------------------
-
-loc_22025:
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		cmp	ax, MISSILE_LEFT_MAX
-		jle	short loc_22040
-		mov	es:[bx+CMissiles.MISSILE_prev_left], (MISSILE_LEFT_MAX shl 4)
-
-loc_22040:
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, MISSILE_TOP_MIN
-		jge	short loc_2205F
-		mov	es:[bx+CMissiles.MISSILE_prev_top], (MISSILE_TOP_MIN shl 4)
-		jmp	loc_220E9
-; ---------------------------------------------------------------------------
-
-loc_2205F:
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, MISSILE_TOP_MAX
-		jle	short loc_220E9
-		mov	es:[bx+CMissiles.MISSILE_prev_top], ((PLAYFIELD_BOTTOM - (MISSILE_H / 2)) shl 4)
-		jmp	short loc_220E9
-; ---------------------------------------------------------------------------
-
-loc_2207D:
-		mov	ax, si
-		mov	bx, 2
-		cwd
-		idiv	bx
-		movsx	eax, dx
-		mov	edx, _frame_rand
-		and	edx, 1
-		cmp	eax, edx
-		jnz	short loc_220A1
-		les	bx, [bp+@@this]
-		add	bx, si
-		inc	es:[bx+CMissiles.MISSILE_flag]
-
-loc_220A1:
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_HIT_last
-		jbe	short loc_220E9
-		mov	bx, word ptr [bp+@@this]
-		add	bx, si
-		mov	es:[bx+CMissiles.MISSILE_flag], MF_FREE
-		push	(16 shl 16) or 32
-		mov	ax, si
-		add	ax, ax
-		mov	bx, word ptr [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_top]
-		sar	ax, 4
-		push	ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_left]
-		sar	ax, 4
-		push	ax
-		call	_egc_copy_rect_1_to_0_16
-		push	7
-		call	_mdrv2_se_play
-		add	sp, 0Ah
-
-loc_220E9:
-		inc	si
-
-loc_220EA:
-		cmp	si, MISSILE_COUNT
-		jl	loc_21F23
-		xor	si, si
-		jmp	loc_221C2
-; ---------------------------------------------------------------------------
-
-loc_220F6:
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_FREE
-		jz	loc_221C1
-		mov	ax, si
-		mov	bx, 2
-		cwd
-		idiv	bx
-		movsx	eax, dx
-		mov	edx, _frame_rand
-		and	edx, 1
-		cmp	eax, edx
-		jnz	loc_221C1
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_MOVING
-		jnz	short loc_22183
-		push	ss
-		lea	ax, [bp+var_4]
-		push	ax
-		push	ss
-		lea	ax, [bp+var_2]
-		push	ax
-		push	si
-		pushd	[bp+@@this]
-		call	sub_21CA3
-		push	[bp+var_4]
-		push	[bp+var_2]
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		push	ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		push	ax
-		call	_ptn_put_quarter
-		add	sp, 16h
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		mov	es:[bx+CMissiles.MISSILE_prev_left], ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		mov	es:[bx+CMissiles.MISSILE_prev_top], ax
-		jmp	short loc_221C1
-; ---------------------------------------------------------------------------
-
-loc_22183:
-		les	bx, [bp+@@this]
-		add	bx, si
-		mov	al, es:[bx+CMissiles.MISSILE_flag]
-		mov	ah, 0
-		add	ax, -MF_HIT
-		push	ax
-		mov	bx, word ptr [bp+@@this]
-		mov	al, es:[bx+CMissiles.MISSILE_ptn_id_base]
-		mov	ah, 0
-		add	ax, MISSILE_HIT_IMAGE
-		push	ax
-		mov	ax, si
-		add	ax, ax
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_top]
-		sar	ax, 4
-		push	ax
-		mov	ax, es:[bx+CMissiles.MISSILE_prev_left]
-		sar	ax, 4
-		push	ax
-		call	_ptn_put_quarter
-		add	sp, 8
-
-loc_221C1:
-		inc	si
-
-loc_221C2:
-		cmp	si, MISSILE_COUNT
-		jl	loc_220F6
-		cmp	_player_invincible, 0
-		jnz	short loc_22231
-		xor	si, si
-		jmp	short loc_2222C
-; ---------------------------------------------------------------------------
-
-loc_221D4:
-		les	bx, [bp+@@this]
-		add	bx, si
-		cmp	es:[bx+CMissiles.MISSILE_flag], MF_FREE
-		jz	short loc_2222B
-		mov	ax, si
-		add	ax, ax
-		les	bx, [bp+@@this]
-		add	bx, ax
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		mov	dx, _player_left
-		add	dx, -8
-		cmp	ax, dx
-		jle	short loc_2222B
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_left]
-		sar	ax, 4
-		mov	dx, _player_left
-		add	dx, 24
-		cmp	ax, dx
-		jge	short loc_2222B
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, (_player_top + PLAYER_H)
-		jge	short loc_2222B
-		mov	ax, es:[bx+CMissiles.MISSILE_cur_top]
-		sar	ax, 4
-		cmp	ax, (_player_top - 8)
-		jle	short loc_2222B
-		mov	_done, 1
-		jmp	short loc_22231
-; ---------------------------------------------------------------------------
-
-loc_2222B:
-		inc	si
-
-loc_2222C:
-		cmp	si, MISSILE_COUNT
-		jl	short loc_221D4
-
-loc_22231:
-		pop	si
-		leave
-		retf
-sub_21F19	endp
-
+	extern @CMissiles@unput_update_render$qv:proc
 	extern @particles_unput_update_render$q17particle_origin_ti:proc
 main_32__TEXT	ends
 
@@ -23809,7 +23472,7 @@ var_4		= word ptr -4
 		push	di
 		mov	eax, dword ptr _elis_invincibility_flash_colors
 		mov	[bp+@@invincibility_flash_colors], eax
-		call	sub_21F19 c, offset _Missiles, ds
+		call	@CMissiles@unput_update_render$qv c, offset _Missiles, ds
 		cmp	_boss_phase, 0
 		jnz	loc_281CF
 		call	@boss_palette_snap$qv