Research: Critical Capture

ghoulslash · Dec 10, 2017

Thanks to Daniils and JPAN and everyone else who has worked on expanding pokeballs, we can expand pokeballs and create custom catch rate functions. However, I have yet to see any work on porting the critical capture to Gen 3 games (at least any public work)

I would like to share some research I have done into the subject. I noticed from koople's dodge rate routine that there is some index that appears to determine the outcome of the throw (see below).

First, some info on how the catch rate and subsequent success is determined:
1. The catch rate is calculated starting at 0802d620 and finally loaded into r6:

Spoiler:

2. There is then a check for safari ball and master ball, and we jump to 0802d6a8 for everything else. Eventually, we end up at 0802d752, which is a loop that gets a random value, and compares to the catch rate in r6.

Spoiler:

The loop incrementally increases r4 to a maximum value of 0x4, which holds the "catch index" as follows:

Code:

r4 = 0x0 --> breakout immediately
r4 = 0x1 --> shake once and breakout
r4 = 0x2 --> shake twice and breaout
r4 = 0x3 --> shake three times and breakout
r4 = 0x4 --> shake three times and catch
r4 = 0x5 --> trainer deflection (handled separately)
r4 = 0x6 --> ghost battle dodge (handled separately)
r4 > 0x6 -> ball rolls [r4] times and breaks out. sort of funny to watch it roll 10 times

An non-ideal critical capture routine could be made with a tentative algorithm such as this:

Code:

1. get ratio of caught pokemon to pokedex size
2. check brackets via [URL="https://bulbapedia.bulbagarden.net/wiki/Catch_rate#Critical_capture"]this guide[/URL]
3. get crit_catch_rate * catch_rate (eg. (0 - 2.5)*r6)
4. get random value via 08044ec8
5. compare critical capture rate to random value
6. if lower, critical capture has occurred. otherwise, perform regular capture checks (ie jump to 0802d752)
7. for critical capture: only perform one "shake check". 
7a. set r4 to 0x2 and jump to 0802d74c, or do logic yourself

This routine would theoretically imitate the logic for critical capture; however, the pokeball would still shake three times before capture instead of just once. I haven't had much luck with figuring out how the number of shakes is tied to the catch index yet. I have to imagine it is related to the ball object template table, as it contains data that appears to be related to "shaking" the pokeball. I would guess that the game loops over some animation related to shaking the pokeball based on the value of the "catch index" above.

(hopefully) more to follow. I hope to having a working code of the proposed algorithm soon.

EDIT: Here is an initial working version of the critical capture algorithm. The shaking animation and throwing sound need to be fixed, still

Spoiler:

Code:

.text
.align 2
.thumb
.thumb_func
.global CriticalCapture
/*
insert 00 48 00 47 (xx+1) xx xx 08 at 2d67c

see 2nd post in thread for notes about routine
*/

Main:
	ldrh r0, [r1]		@thrown ball
	cmp r0, #0x5
	beq SafariBall
	cmp r0, #0x1
	bne CheckNationalDex
	
MasterBall:
	ldr r0, =(0x0802d686 +1)
	bx r0
	
SafariBall:
	ldr r0, =(0x0802d6bc +1)
	bx r0
	
CheckNationalDex:
	mov r7, r6
	push {r2-r6}
	ldr r0, .TrainerData
	ldr r0, [r0]
	ldrb r0, [r0, #0x1b]
	cmp r0, #0xb9	@[0300500c] + 0x1b set to 0xb9 with special 0x16F to enable national dex
	bne LocalDex
	ldr r0, =(0x00000840)	@flag 0x840 set with sp. 0x16f (redundant check but whatevs)
	bl CheckFlag
	cmp r0, #0x0	
	beq LocalDex
	
NationalDex:
	mov r0, #0x1
	bl GetNationalDexCount
	b CheckBrackets
	
LocalDex:
	mov r0, #0x1
	bl GetLocalDexCount
		
CheckBrackets:
	mov r5, r0		@r5 = num caught pokemon
	ldr r6, =(0x00000xxx)	@r7 = size of your pokedex (0x182 = 386 if no expanded dex)
	
CheckLargest:
	mov r4, #0x19	@2.5x critical capture rate
	lsr r0, r6, #0x2
	sub r0, r6, r0		@3/4 dex size
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check2nd:
	mov r4, #0x14
	mov r0, #0x9
	mul r0, r6
	mov r1, #0x10	@9/16ths dex size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check3rd:
	mov r4, #0xF	
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x8	   @3/8ths dex_size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check4th:
	mov r4, #0xA
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x10	@3/16ths dex size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
CheckLast:
	mov r4, #0x5
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x50	@3/80ths dex size
	bl Divide
	cmp r5, r0
	bls NoCriticalCapture
	
GetCritCatchMultiplier:
	mov r0, r4		@critical capture chance multiplier
	mul r0, r7
	pop {r2-r6}
	mov r6, r7
	mov r1, #0x3C
	bl Divide	@r0 = c = (([0:5:25] x catch rate) / 10)  /  6)
	push {r0}
	bl Random
	mov r1, r0
	lsl r1, r1, #0x18
	lsr r1, r1, #0x18
	pop {r0}
	cmp r1, r0
	bls CritCapture	@if rand(0,255) <= c, critical capture occurs
	
NoCriticalCapture:
	pop {r2-r6}
	ldr r0, =(0x0802d6a8 +1)	@return to check all 3 shakes
	bx r0
	
CritCapture:
	bl Random
	lsl r0, r0, #0x18
	lsr r0, r0, #0x18
	cmp r0, r6
	bcc SuccessCritCatch	@rand < catch rate
	
FailedCritCapture:
	mov r4, #0x1			@shake once and breakout
	ldr r0, =(0x0802d76c +1)
	bx r0
	
SuccessCritCatch:
	mov r4, #0x4
	ldr r0, =(0x08xxxxxx)		@battle script to load (see below for example)
	ldr r1, .ScriptPointer
	str r0, [r1]
	mov r0, #0x0
	mov r1, #0x4		@3 shakes then catch - need to find a way to make 1 shake and catch
	ldr r2, =(0x0800E194 +1)    @store catch index
	bl jump_r2
	ldr r0, =(0x02023bc4)
	ldrb r0, [r0]
	ldr r2, =(0x08017248 +1)
	bl jump_r2
	ldr r1, =(0x0802d6d6 +1)
	bx r1
	
Random:
	ldr r2, =(0x08044ec8 +1)
	b jump_r2	
	
Divide:
	ldr r2, =(0x081e4018 +1)
	
jump_r2:
	bx r2
	
CheckFlag:
	ldr r1, =(0x0806e6d0 +1)
	bx r1
	
GetLocalDexCount:
	ldr r4, =(0x08088edc +1)
	bx r4
	
GetNationalDexCount:
	ldr r4, =(0x08088e8c +1)
	bx r4
		
.align 2
.ScriptPointer:	.word 0x02023d74
.TrainerData:	.word 0x0300500c
	
	
/* battle script example:

#org @start
setword 0x0203c020 0x08xxxxxx		//custom critical capture string
jumpifhalfword 0x0 0x2023D68 0x5 @safari
cmd60 0xB
printstring 0x184
goto 0x8165781

#org @safari
printstring 0x184
goto 0x81D9A53     //catch pokemon

*/

AkameTheBulbasaur · Dec 19, 2017

Hey this is pretty cool!

Last summer I was trying to figure out a similar sort of mechanic. I was trying to have a chance of being guaranteed to capture the pokemon based in certain things like level differences or Speed boosts. I forgot how it worked because I never ended up using it.

The part that I had the most trouble with was getting the game to have a separate animation for when these sorts of captures would occur. Well, not really a separate animation as much as having different sound effects, much like how actual critical captures have a different sound effect when the ball is thrown.

I'd been looking at the battle scripts called when Poke Balls are thrown but I found nothing that I could make use of :(. Hopefully we can all figure something out.

ghoulslash · Dec 20, 2017

AkameTheBulbasaur said:
Hey this is pretty cool!

Last summer I was trying to figure out a similar sort of mechanic. I was trying to have a chance of being guaranteed to capture the pokemon based in certain things like level differences or Speed boosts. I forgot how it worked because I never ended up using it.

The part that I had the most trouble with was getting the game to have a separate animation for when these sorts of captures would occur. Well, not really a separate animation as much as having different sound effects, much like how actual critical captures have a different sound effect when the ball is thrown.

I'd been looking at the battle scripts called when Poke Balls are thrown but I found nothing that I could make use of :(. Hopefully we can all figure something out.

Yeah the animation/sound effects seems to be the trickiest part. The battle scripts appear to only print the relevant strings/add data to pokedex/etc after the animation has run its course.

With that, here is a bit more preliminary research I've done:

Spoiler:

I've also come up with a (fully?) working 'critical capture' routine using the algorithm I originally described. It also allows for a custom string to be displayed when critical capture succeeds:

Spoiler:

Assembly Routine: insert 00 48 00 47 (xx+1) xx xx 08 at 2d67c

Spoiler:

Code:

.text
.align 2
.thumb
.thumb_func
.global CriticalCapture

Main:
	ldrh r0, [r1]		@thrown ball
	cmp r0, #0x5
	beq SafariBall
	cmp r0, #0x1
	bne CheckNationalDex
	
MasterBall:
	ldr r0, =(0x0802d686 +1)
	bx r0
	
SafariBall:
	ldr r0, =(0x0802d6bc +1)
	bx r0
	
CheckNationalDex:
	mov r7, r6
	push {r2-r6}
	ldr r0, .TrainerData
	ldr r0, [r0]
	ldrb r0, [r0, #0x1b]
	cmp r0, #0xb9	@[0300500c] + 0x1b set to 0xb9 with special 0x16F to enable national dex
	bne LocalDex
	ldr r0, =(0x00000840)	@flag 0x840 set with sp. 0x16f (redundant check but whatevs)
	bl CheckFlag
	cmp r0, #0x0	
	beq LocalDex
	
NationalDex:
	mov r0, #0x1
	bl GetNationalDexCount
	b CheckBrackets
	
LocalDex:
	mov r0, #0x1
	bl GetLocalDexCount
		
CheckBrackets:
	mov r5, r0		@r5 = num caught pokemon
	ldr r6, =(0x00000xxx)	@r7 = size of your pokedex (0x182 = 386 if no expanded dex)
	
CheckLargest:
	mov r4, #0x19	@2.5x critical capture rate
	lsr r0, r6, #0x2
	sub r0, r6, r0		@3/4 dex size
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check2nd:
	mov r4, #0x14
	mov r0, #0x9
	mul r0, r6
	mov r1, #0x10	@9/16ths dex size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check3rd:
	mov r4, #0xF	
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x8	   @3/8ths dex_size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
Check4th:
	mov r4, #0xA
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x10	@3/16ths dex size
	bl Divide
	cmp r5, r0
	bgt GetCritCatchMultiplier
	
CheckLast:
	mov r4, #0x5
	mov r0, #0x3
	mul r0, r6
	mov r1, #0x50	@3/80ths dex size
	bl Divide
	cmp r5, r0
	bls NoCriticalCapture
	
GetCritCatchMultiplier:
	mov r0, r4		@critical capture chance multiplier
	mul r0, r7
	pop {r2-r6}
	mov r6, r7
	mov r1, #0x3C
	bl Divide	@r0 = c = (([0:5:25] x catch rate) / 10)  /  6)
	push {r0}
	bl Random
	mov r1, r0
	lsl r1, r1, #0x18
	lsr r1, r1, #0x18
	pop {r0}
	cmp r1, r0
	bls CritCapture	@if rand(0,255) <= c, critical capture occurs
	
NoCriticalCapture:
	pop {r2-r6}
	ldr r0, =(0x0802d6a8 +1)	@return to check all 3 shakes
	bx r0
	
CritCapture:
	bl Random
	lsl r0, r0, #0x18
	lsr r0, r0, #0x18
	cmp r0, r6
	bcc SuccessCritCatch	@rand < catch rate
	
FailedCritCapture:
	mov r4, #0x1			@shake once and breakout
	ldr r0, =(0x0802d76c +1)
	bx r0
	
SuccessCritCatch:
	mov r4, #0x4
	ldr r0, =(0x08xxxxxx)		@battle script to load (see below for example)
	ldr r1, .ScriptPointer
	str r0, [r1]
	mov r0, #0x0
	mov r1, #0x4		@3 shakes then catch - need to find a way to make 1 shake and catch
	ldr r2, =(0x0800E194 +1)    @store catch index
	bl jump_r2
	ldr r0, =(0x02023bc4)
	ldrb r0, [r0]
	ldr r2, =(0x08017248 +1)
	bl jump_r2
	ldr r1, =(0x0802d6d6 +1)
	bx r1
	
Random:
	ldr r2, =(0x08044ec8 +1)
	b jump_r2	
	
Divide:
	ldr r2, =(0x081e4018 +1)
	
jump_r2:
	bx r2
	
CheckFlag:
	ldr r1, =(0x0806e6d0 +1)
	bx r1
	
GetLocalDexCount:
	ldr r4, =(0x08088edc +1)
	bx r4
	
GetNationalDexCount:
	ldr r4, =(0x08088e8c +1)
	bx r4
		
.align 2
.ScriptPointer:	.word 0x02023d74
.TrainerData:	.word 0x0300500c
	
	
/* battle script example:

#org @start
setword 0x0203c020 0x08xxxxxx		//custom critical capture string
jumpifhalfword 0x0 0x2023D68 0x5 @safari
cmd60 0xB
printstring 0x184
goto 0x8165781

#org @safari
printstring 0x184
goto 0x81D9A53     //catch pokemon

*/

A little info on how it works:

The critical catch rate is determined by the number of pokemon registered in the pokedex, with >600 being the highest bracket.
I broke the values from here into rough fractions of the total number of pokemon in the game, which I rounded to 800. so >75% is the highest multiplier, then 9/16ths (450/800), and so on.
Let's call this multiplier y
The number of registered pokemon is obtained, and each bracket is checked. Then, a random value is compared to the 'critical catch rate, x, where x = a*y / 6.
Note: I divide by 60 in the routine because each y is a multiple of 10 (eg. 2.5x = 25).
If this random value, rand(0,255) < x, critical capture occurs.
If critical capture occurs, a new random value is obtained, rand(0,255), and compared to the original catch rate, a. if rand(0,255) < a, critical capture is a success. Otherwise, the pokemon breaks out after a single shake.

So just change the ldr r6, =(0x00000xxx) to the size of your pokedex in hex, and fix the pointer at the end to your custom critical capture battle script, and you are good to go! Also feel free to tamper with the formula, obviously.

AkameTheBulbasaur · Dec 23, 2017

So I've figured out how to add a new animation for critical captures.

There's a table at 0x1C6F18 that has a bunch of pointers to animations. The important one is the third entry, 0x1D64F9, which is the PokeBall throwing animation.

You can repoint this table and add a new entry for your new animation.

I used a small routine to actually reroute the game to play your new animation.

Spoiler:

Essentially the way this works is you put a 1 into 0x020370D6. This is the RAM for the temporary var 8010. This will stay the same throughout the battle, so you can set this to 1 during the catch rate routine and then it will know to play the other animation. I picked 8010 for this because it was a var I thought most people wouldn't need to actually use. This, of course, can be changed for some other piece of RAM, but do so at your own risk.

Now for the animation, I just used the default animation, but changed the "19 36 00" to "19 BB AA" where AABB is the sound you want the game to play.

For good measure, I also made a routine for determining guaranteed capture. It's based on the difference between your Speed and the foe's Speed. In other words, if you have a much higher Speed than the wild Pokemon, there is a chance for a guaranteed capture (regardless of Poke Ball) that approached 50%.

For example, if you and the wild Pokemon have the exact same Speed stat, the chance will be 25%.

Spoiler:

ghoulslash · Dec 23, 2017

Awesome work, Akame! Here's a bit more info on the copied animation at 1d64f9:

Code:

03 91 F4 0E 08 02 00 04 00    -> call task 080ef490
19 36 00 00 				-> play throw pokeball sound (0x36)
03 AD F5 0E 08 02 00 		-> 080ef5ac  -> must somehow related to catching
03 E1 F4 0E 08 02 00 		-> call task 080ef4e0 (check trainer block vs. dodgeball indices)
21 07 FF FF 2D 65 1D 08   -> jump to 1d652d if trainer deflection
21 07 FE FF 55 65 1D 08   -> jump to 1d6555 if dodging animation
05 
03 B9 F4 0E 08 02 00   -> call task 080ef4b8
08

Task 080ef5ac loads the ball object table/ball ID, and has a BL to 08074480. This routine looks like so:

Code:

08074480 b530 push {r4,r5,lr}
08074482 0600 lsl r0, r0, #0x18
08074484 0e05 lsr r5, r0, #0x18
08074486 0609 lsl r1, r1, #0x18
08074488 0e0c lsr r4, r1, #0x18
0807448a 2c04 cmp r4, #0x4
0807448c d838 bhi $08074500	  @table limiter or catch index limiter?
0807448e 00a0 lsl r0, r4, #0x02
08074490 4901 ldr r1, [$08074498] (=$0807449c)
08074492 1840 add r0, r0, r1
08074494 6800 ldr r0, [r0, #0x0]
08074496 4687 mov pc, r0

The table at 7449c: (I think a routine is loaded based on the catch index?)
080744b0
080744d8 -> these first three routines appear to load a byte from some table at 3ae01c, not sure what it does
080744b0
08074500 -> my hunch is that this routine results in actually catching the pokemon
08074500:

Spoiler:

I haven't messed around too much with these routines, but I am fairly confident that 080ef5ac determines the shake animations.

Research: Critical Capture

More options

ghoulslash

AkameTheBulbasaur

Akame Marukawa of Iyotono

ghoulslash

AkameTheBulbasaur

Akame Marukawa of Iyotono

ghoulslash