[Sodaholic]

EDIT: decided to turn this thread into a personal version of the basic answers and questions thread. The reason for this is because I have many questions, and don't want to flood the existing thread, as I want them to have their questions answered as well.



Not sure if it's a good idea to make this it's own thread, but as it's own thread, it's more likely to get noticed than in the general hacking help thread. Sorry if this is kind of annoying being in the hacking forum, but I figured it would be more appropriate here than in the member's lounge

I'm still a total novice at ASM, and while I have a basic understanding of ASM, I'm not at all familiar with the internal workings of the Sonic engine. I am fully capable of editing art and levels, and even music to some extent, but the code is what really gets me. Basically, I was wondering if there's any guru out there that would be willing to help a novice out a bit. (not hold my hand, I don't want that. I just need a little help getting off the ground, and having interactive examples and lessons to teach me how to get around in the Sonic engine)

I know there's tutorials on the wiki, but I've used them and don't feel that I learned very much, besides just ASM, not actually explaining what the Sonic engine does and how. What I mean is that it doesn't really explain things on a larger scale (the whole picture), it only provides steps with how to do a specific task. Having an interactive teacher that explains why and how things work the way they do, rather than just show me steps to a solution, would work much better.

Anyway, is there anyone out there willing to help? I'm not looking for someone to do the work for me, just kind of a hacking "mentor". I am willing to compensate you monetarily for your efforts (as long as it's low enough, I don't exactly have very much cash), if you feel it necessary. Again, I emphasize that I don't want to have my hand held, only a guide.

I'd also like to point out that I prefer real time conversation (text or voice), as it allows me to ask questions and get answers more quickly and efficiently than PM or email.

This post has been edited by Sodaholic: 01 December 2011 - 08:36 PM

[MarkeyJester]

I always find that the individuals who you're most likely looking for as a mentor, are those whom of which are too busy to help, of course, have you considered popping onto badnik.net on irc and asking in some of the public channels? A few people pop into #ssrg on a basis and ask a few questions there, and there are plenty of people around who usually break things down and explain them, I'm not sure about #retro (that's usually quite crowded and often you can't get a word in), but there are bound to be a whole load of public channels in general, where people will be more than friendly enough to help answer any questions you might have about the game engines as a whole.

[Sodaholic]

I'll consider popping into some of those channels, thanks for recommending them.

Anyway, I've decided to turn this into a personal version of the basic answers and questions thread, as I have many questions and do not want to flood the existing thread, so that others have a chance of getting their questions answered.


I'm creating a hack in Sonic 2 using the Xenowhirl disassembly. My questions are ordered from most to least priority.

How would I go about recreating the Sonic Triple Trouble HUD in Sonic 2? I want to remove score entirely, and I want to add trailing 0's to the rings and lives counter. I want the rings counter to be fixed at 3 digits, and I want the lives counter to be fixed at 2 digits. I also only want the icon to remain of the lives counter, and not have the "x" or name in it. I'd also like to have it use the large 8x16 font instead of the small 8x8 font that it already uses. Also, how would I be able to have a spinning ring in the hud? And lastly, be able to just outright remove the Score Time Rings part of the HUD.

Another question, how can I set Sonic Alone as the default player in Sonic 2?

And lastly, how could I make the ring animation 8 frames instead, and change the animation speed to accommodate this?

[E-122-Psi]

Sodaholic, on 01 December 2011 - 08:43 PM, said:

I'll consider popping into some of those channels, thanks for recommending them.

Anyway, I've decided to turn this into a personal version of the basic answers and questions thread, as I have many questions and do not want to flood the existing thread, so that others have a chance of getting their questions answered.


I'm creating a hack in Sonic 2 using the Xenowhirl disassembly. My questions are ordered from most to least priority.

How would I go about recreating the Sonic Triple Trouble HUD in Sonic 2? I want to remove score entirely, and I want to add trailing 0's to the rings and lives counter. I want the rings counter to be fixed at 3 digits, and I want the lives counter to be fixed at 2 digits. I also only want the icon to remain of the lives counter, and not have the "x" or name in it. I'd also like to have it use the large 8x16 font instead of the small 8x8 font that it already uses. Also, how would I be able to have a spinning ring in the hud? And lastly, be able to just outright remove the Score Time Rings part of the HUD.

Another question, how can I set Sonic Alone as the default player in Sonic 2?

And lastly, how could I make the ring animation 8 frames instead, and change the animation speed to accommodate this?

The Life Icon can be editted easily in SonMapEd (the number tiles for the lives will be harder to edit however). HUD data I'm less knowledgeable about.

As for ring animations, I'm not positive but there could be an animation script in the ASM that you can edit, make more sprites in SonMapEd and then add them onto the animation loop data. A speed level should be on there too, usually the first number after dc.b, make it smaller and it will take less frames to run.

This post has been edited by E-122-Psi: 01 December 2011 - 09:32 PM

[Sodaholic]

I'm having a difficult time finding the ring animation script using the search function. Oh well. Anyone know how to edit the HUD though? Or the default player? I want all games to be started with Sonic Alone by default, not Sonic and Tails.

[FraGag]

Editing the HUD
Editing the HUD is somewhat difficult. You can edit the mappings in SonMapEd, but there's no art file you can load because the art is dynamically refreshed on each frame. You can, however, take a savestate, extract the VRAM starting at $D940 (where the HUD patterns start in VRAM) from the savestate, and load that as the art file.

Forcing leading zeroes on the HUD is done in the code. The HudUpdate subroutine updates the patterns in VRAM that are used the HUD sprite mappings. Just remove these lines to get leading zeroes for the score and rings (you probably don't care about the score since you want to remove it):

	tst.w	d2
	beq.s	loc_4116A
	move.w	#1,d4

loc_4116A:
	tst.w	d4
	beq.s	loc_41198

Here, d2 is the value of the current digit. When it encounters a digit that is not zero, it sets d4 to 1. Zeroes that come before d4 is set to 1 are left blank, and zeroes that come after d4 is set are drawn as "0". By removing these lines, we always draw all zeroes as "0". Since the rings counter is already programmed for 3 digits, you don't have anything else to do for the rings counter!

For the lives counter, it's the same pattern, but elsewhere. Remove these lines:

	tst.w	d2
	beq.s	loc_41314
	move.w	#1,d4

loc_41314:
	tst.w	d4
	beq.s	Hud_ClrLives

To get an animated ring in the HUD, I'd create a new object type (or add a routine to an existing object, like Obj25) that uses the same art_tile, mappings and animation code as the debug ring object type (Obj25) or scattering ring object type (Obj37), but without collision and with screen-space coordinates.

Default player configuration
There are 2 variables controlling the player configuration: Player_option and Player_mode. The value of Player_option is the value selected on the options screen. Player_mode is the value actually used during a level. When a level is started, if the game is playing a demo or in 2P versus mode, Player_mode is forced to 0 (Sonic and Tails); otherwise, the value of Player_option is used.

The value of Player_option is never explicitly set; it is set to 0 when the game clears most of the RAM on startup. I think the best place to set it is just before the MainGameLoop label:

	move.b	#GameModeID_SegaScreen,(Game_Mode).w	; => SegaScreen
	move.w	#1,(Player_option).w	; +++
; loc_394:
MainGameLoop:
	move.b	(Game_Mode).w,d0

This way, it's set to Sonic alone on reset, but it won't override the choice the player made on the options screen.

Ring animation
The ring animation is controlled globally; all rings display the same frame at the same time. The Rings_anim_frame variable specifies what's the current frame. The ChangeRingFrame subroutine controls that variable, and uses Rings_anim_counter to control the animation speed. This is the original code:

	subq.b	#1,(Rings_anim_counter).w
	bpl.s	+
	move.b	#7,(Rings_anim_counter).w
	addq.b	#1,(Rings_anim_frame).w ; animate rings in the level (obj25)
	andi.b	#3,(Rings_anim_frame).w
+

When Rings_anim_counter becomes negative, its value is reset to 7 and the current frame is incremented by 1. The ANDI instruction then restricts the value to the 0-3 range. If you want to double the number of frames while keeping the same duration for an animation cycle, you'll need to reset Rings_anim_counter to 3 and use andi.b #7,(Rings_anim_frame).w. Then, you'll have to add frames between the existing frames in the mappings (obj37_a.bin). Note that this will move the sparkle frames, so you'll have to fix the animation script for it (Ani_Ring). Change dc.b 5,4,5,6,7,$FC to dc.b 5,8,9,$A,$B,$FC in Ani_Ring to reference the new frame numbers of the sparkle frames.

Spilled rings use a separate counter: Ring_spill_anim_counter. The algorithm to control it is a bit more complicated:

	tst.b	(Ring_spill_anim_counter).w
	beq.s	+	; rts
	moveq	#0,d0
	move.b	(Ring_spill_anim_counter).w,d0
	add.w	(Ring_spill_anim_accum).w,d0
	move.w	d0,(Ring_spill_anim_accum).w
	rol.w	#7,d0
	andi.w	#3,d0
	move.b	d0,(Ring_spill_anim_frame).w ; animate scattered rings (obj37)
	subq.b	#1,(Ring_spill_anim_counter).w
+

Change rol.w #7,d0 to rol.w #6,d0 and change andi.w #3,d0 to andi.w #7,d0. The first change should preserve the animation speed and the second change will use all 8 frames.

[Sodaholic]

Thank you, this worked out perfectly. I cannot find Ani_Ring in the disassembly. I downloaded it off of the disassembly page on the wiki, so it may be out of date and have a different label, perhaps?

Also, how do I expand the art tiles for the rings? I don't know how to increase the file size of the art to add new tiles, and I'm worried about how it's going to fit into VRAM. The only amount of space that I need is 8 new 8x8 tiles (as in 2 16x16 tiles, I'm trying to port Chaotix's enhanced ring animation).

My disassembly also lacks obj25.bin and obj37.bin in the sprite mappings folder, yet rings still appear in the rom. What could the mappings file be named?

This post has been edited by Sodaholic: 03 December 2011 - 03:56 PM

[FraGag]

Sodaholic, on 03 December 2011 - 01:03 PM, said:

Thank you, this worked out perfectly. I cannot find Ani_Ring in the disassembly. I downloaded it off of the disassembly page on the wiki, so it may be out of date and have a different label, perhaps?

Also, how do I expand the art tiles for the rings? I don't know how to increase the file size of the art to add new tiles, and I'm worried about how it's going to fit into VRAM. The only amount of space that I need is 8 new 8x8 tiles (as in 2 16x16 tiles, I'm trying to port Chaotix's enhanced ring animation).

My disassembly also lacks obj25.bin and obj37.bin in the sprite mappings folder, yet rings still appear in the rom. What could the mappings file be named?

Ani_Ring might be named byte_1237A in your disassembly. As for increasing the file size, it depends on the program you use to edit the art. If you're afraid the art might not fit in VRAM, maybe you could use DPLCs to reload only the visible frame (separately for each counter), while keeping the sparkle frames as they are currently. The mappings should be named obj37_a.bin in mappings/sprite; I don't think the file names changed since the 2007 disassembly.

[Sodaholic]

It's almost perfect, but still a few kinks. The ring animation now works perfectly, but only on rings that have been spilled. The regular rings still have the old mappings, it doesn't appear to use obj37_a.bin, only the spilled rings appear to.

Also, it's still displaying frames 5-8 instead of 9-12 when I pick up a spilled ring, but it does display frames 9-12 on a regular ring when I pick it up (actually, come to think of it, it's probably still 5-8, since it's using the old mappings). Here's the code I have so far:

; ===========================================================================
byte_1237A:
dc.b 0

dc.b 2 ; 1
dc.b 5 ; 2
dc.b 8 ; 3
dc.b 9 ; 4
dc.b $A ; 5
dc.b $B ; 6
dc.b $FC ; 7
; -------------------------------------------------------------------------------


Lastly, it does cut into other tiles in the VRAM, but it conveniently only cuts into the SCORE TIME RINGS text, which I planned on removing anyway. I'll worry about the HUD later, I want to get these rings fixed first.

Also, thanks for taking the time to help an ASM-illiterate moron such as myself. :P

This post has been edited by Sodaholic: 03 December 2011 - 10:00 PM

[FraGag]

The rings in Sonic 2 aren't objects like in Sonic 1. Instead, they're handled by the "rings manager". The rings laid out in the ring layout use the mappings in mappings/sprite/Rings.bin (which are not exactly sprite mappings, annoyingly; the number of sprites is missing (a single sprite is assumed)); you'll have to edit those to add your new frames (you can copy the mappings from your edited obj37_a.bin).

If the svn disassembly isn't lying, this line sets the frame and destruction timer when a ring is collected:

loc_17148:
	move.w	#$604,(a1)

Change $604 to $608 to use the sparkle frames in their new location.

[Sodaholic]

Two problems. One, Rings.bin doesn't exist in /mappings/sprite/ in my copy, nor anything similarly named. Second, when I made that code modification ($604 to $608), the most bizarre and unexpected thing happened: whenever you pick up a ring, it simply disappears without the sparkles, and then random garbled crap just flashes all over the screen until you walk off screen from where you picked the ring up.

When I reverted it back to $604, the problem went away.




Ignore the HUD garbling, I don't really care that it's that messed up, it's going to be revamped and replaced anyway.

Speaking of the HUD, how can I change the position of the HUD elements? I want to be able to move the score number completely offscreen, or simply outright remove it if possible. I then want to adjust the X and Y positions of the lives, rings, and time numbers on screen. Lastly, I need to have the lives number use the big font instead of the small font.

Note that I don't want to change the position of the SCORE TIME RINGS object, but rather just have it be completely static (no animations, just one, consistent state).

This post has been edited by Sodaholic: 04 December 2011 - 12:17 AM

[FraGag]

Sodaholic, on 04 December 2011 - 12:07 AM, said:

Two problems. One, Rings.bin doesn't exist in /mappings/sprite/ in my copy, nor anything similarly named. Second, when I made that code modification ($604 to $608), the most bizarre and unexpected thing happened: whenever you pick up a ring, it simply disappears without the sparkles, and then random garbled crap just flashes all over the screen until you walk off screen from where you picked the ring up.

When I reverted it back to $604, the problem went away.




Ignore the HUD garbling, I don't really care that it's that messed up, it's going to be revamped and replaced anyway.

That's because you need to change the mappings before using them!

The mappings are at off_1736A in the 2007 disassembly. The first four entries are the ring frames, and the next four entries are the sparkle frames.

Sodaholic, on 04 December 2011 - 12:07 AM, said:

Speaking of the HUD, how can I change the position of the HUD elements? I want to be able to move the score number completely offscreen, or simply outright remove it if possible. I then want to adjust the X and Y positions of the lives, rings, and time numbers on screen. Lastly, I need to have the lives number use the big font instead of the small font.

Note that I don't want to change the position of the SCORE TIME RINGS object, but rather just have it be completely static (no animations, just one, consistent state).

The whole HUD is one big mapping (hud_a.bin). These mappings have 4 frames: the 2nd, 3rd and 4th frame have the time and/or rings counter in red. Just remove the "pieces" you don't want from each frame and move the other pieces where you want them to appear.

To get larger numbers for the lives counter, replace $5FA00003 in the Hud_Lives2 routine with $5F800003, and replace the Hud_Lives routine (up to the ; End of function Hud_Lives line) with this:

Hud_Lives:
	move.l	#$7B800003,d0
	moveq	#0,d1
	move.b	(Life_count).w,d1

loc_412EE:
	lea	Hud_10(pc),a2
	moveq	#1,d6
	moveq	#0,d4
	lea	Art_Hud(pc),a1
	move.l	d0,4(a6)
; loc_412FA:
Hud_LivesLoop:
	moveq	#0,d2
	move.l	(a2)+,d3
-	sub.l	d3,d1
	bcs.s	loc_4130A
	addq.w	#1,d2
	bra.s	-
; ===========================================================================

loc_4130A:
	add.l	d3,d1
	tst.w	d2
	beq.s	loc_41314
	move.w	#1,d4

loc_41314:
	tst.w	d4
	beq.s	Hud_ClrLives

loc_41318:
	lsl.w	#6,d2
	lea	(a1,d2.w),a3
    rept 16
	move.l	(a3)+,(a6)
    endm

loc_4132E:
	dbf	d6,Hud_LivesLoop ; repeat 1 more time
	rts
; ===========================================================================
; loc_4133A:
Hud_ClrLives:
	tst.w	d6
	beq.s	loc_41318
	moveq	#$F,d5
; loc_41340:
Hud_ClrLivesLoop:
	move.l	#0,(a6)
	dbf	d5,Hud_ClrLivesLoop
	bra.s	loc_4132E
; End of function Hud_Lives

If you don't need the HUD mapping frames with the TIME and/or RINGS in red, you can remove those frames altogether (Edit > Sprite > Delete Sprite in SonMapEd). However, if you do that, the game must not try to use them anymore; to do that, remove these lines under loc_40804:

	btst	#3,($FFFFFE05).w
	bne.s	BranchTo_loc_40836
	cmpi.b	#9,(Timer_minute).w
	bne.s	BranchTo_loc_40836
	addq.w	#2,d1

BranchTo_loc_40836 
	bra.s	loc_40836
; ===========================================================================

loc_40820:
	moveq	#0,d1
	btst	#3,($FFFFFE05).w
	bne.s	loc_40836
	addq.w	#1,d1
	cmpi.b	#9,(Timer_minute).w
	bne.s	loc_40836
	addq.w	#2,d1

loc_40836:

[Sodaholic]

When I remove those lines of code to make the STR object not animate, it doesn't build, complaining that loc_40820 cannot be found (because it was removed and is still being referenced a few lines back). I reverted it so that it could build again, and found a cheap-ass solution of just duplicating the frames, which is, well, hacky. :P Despite the cheapness of the solution, I don't mind using it, but it's probably still a good idea to have things done "cleanly".

Also, while that code that's supposed to make the lives counter use the large numbers instead does work, it's back to not having leading zeroes.

The HUD otherwise works perfectly. (I decided against having the ring in the HUD animate)




Anyway, I got the rings to function perfectly now, except one thing. While all animations on both kinds of rings are functioning perfectly (including the sparkles), garbled shit still moves across the screen when I pick up a normal ring when that one variable is set to $608.

[FraGag]

Sodaholic, on 04 December 2011 - 06:58 PM, said:

Also, while that code that's supposed to make the lives counter use the large numbers instead does work, it's back to not having leading zeroes.

Oops, take this Hud_Lives instead:

Hud_Lives:
	move.l	#$7B800003,d0
	moveq	#0,d1
	move.b	(Life_count).w,d1

loc_412EE:
	lea	Hud_10(pc),a2
	moveq	#1,d6
	moveq	#0,d4
	lea	Art_Hud(pc),a1
	move.l	d0,4(a6)
; loc_412FA:
Hud_LivesLoop:
	moveq	#0,d2
	move.l	(a2)+,d3
-	sub.l	d3,d1
	bcs.s	loc_4130A
	addq.w	#1,d2
	bra.s	-
; ===========================================================================

loc_4130A:
	add.l	d3,d1
	lsl.w	#6,d2
	lea	(a1,d2.w),a3
    rept 16
	move.l	(a3)+,(a6)
    endm

loc_4132E:
	dbf	d6,Hud_LivesLoop ; repeat 1 more time
	rts
; End of function Hud_Lives

Sodaholic, on 04 December 2011 - 06:58 PM, said:

Anyway, I got the rings to function perfectly now, except one thing. While all animations on both kinds of rings are functioning perfectly (including the sparkles), garbled shit still moves across the screen when I pick up a normal ring when that one variable is set to $608.

I knew I forgot something (except for the lives counter, I didn't test any of these things :P). There's one more line to change under loc_16FE8:

	cmpi.b	#8,1(a1)

Change the 8 to $C. $C is one more than the last frame ID to use in the sparkling animation.

[Sodaholic]

Thanks, that did the trick.

Where are the settings for how many frames Sonic's walking animation are, and their duration? I want to set the number of frames for walking to 6, and the duration to whatever it was for walking in Sonic 1. I remember doing this about a year ago on my own, but I can't remember where those settings are now. I don't mind having the last 2 frames of each angle of the walking animation going unused, I don't really want to bother with shifting the frames of all the animations at the moment just because I made a tweak somewhere, since it's much more complex than a small number of frames like the rings.


Also, there appears to be a small bug caused by some of the recent changes. Whenever I land a hit on the boss, the black index on the palette remains white instead of reverting to black again after the black and white flashing is done.

This post has been edited by Sodaholic: 05 December 2011 - 03:59 AM