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If you're not interested in the techical details scroll down
As you probably know you can change the behaviourbyte of the grass block from 2 (normal grass) to 3(tall grass) in advancemap. However no animation is played for 3.
Everything starts at 083A70BC which is a table of functions. The interesting entries are at index 1 and 2: 080683C8 and 08068414. They end with:
(the numbers that "overworld_effect_start" uses are the same as for the do_animation npc script command)
overworld_effect_start has a script collection (081D96AC) with it's own bytecode (dispatch table is at 083CBE30). The commands in bytecode are:
Effect 0x4:
Effect 0x11:
Part of the function called from animation 0x4:
Part of the function called from animation 0x11
The last entry in this structure is the callback that executed once every frame. Those are almost equal except for:
To make the tall grass work, a function, equivalent to the one used in the function for normal grass, needs to be written at the same offset.
HOW TO FIX IT
Start overwriting at 08059f34 with 00 21 00 06 00 0e 02 28 01 d0 d1 28 01 d1 01 20 00 e0 00 20 00 21 70 47 03 28 f5 e7
eh 08059f34 0x2100
eh 08059f48 0x2100
eh 08059f4a 0x4770
eh 08059f4c 0x2803
eh 08059f4e 0xE7F5
Have fun and please credit me.
EDIT
If you want to enable the tiny grass too overwrite at 0805A0EC with 0C 30 09 E0. (It's mapped to behaviour byte 7)
As you probably know you can change the behaviourbyte of the grass block from 2 (normal grass) to 3(tall grass) in advancemap. However no animation is played for 3.
Everything starts at 083A70BC which is a table of functions. The interesting entries are at index 1 and 2: 080683C8 and 08068414. They end with:
Code:
08068402 MOVS R0, #4
08068404 BL overworld_effect_start
Code:
0806844E MOVS R0, #0x11
08068450 BL overworld_effect_startoverworld_effect_start has a script collection (081D96AC) with it's own bytecode (dispatch table is at 083CBE30). The commands in bytecode are:
Code:
0 load graphics
1 load palette (v1)
2 load palette (v1)
3 call asm
4 end
5 combination of 0 1 3
6 combination of 0 3
7 combination of 1 3Effect 0x4:
Code:
07 083A5348 [b]080DB349[/b] 04
Code:
07 083A5348 [b]080DB5F5[/b] 04
Code:
...
080DB368 LDR R0, =0x083A0010 @ array of pointers to object templates (see [url]https://www.pokecommunity.com/threads/238937[/url])
080DB36A LDR R0, [R0,#0x10] @ selects the array-entry for the normal grass
...
080DB378 BL template_instanciate
...
Code:
...
080DB614 LDR R0, =0x083A0010 @ array of pointers to object templates (see [url]https://www.pokecommunity.com/threads/238937[/url])
080DB616 LDR R0, [R0,#0x3C] @ selects the array-entry for the tall grass
...
080DB624 BL template_instanciate
...
Code:
083A5420 grass_normal:object_template <0xFFFF, 0x1005, unk_083A36F0, \
083A5420 off_083A541C, stru_083A53DC, \
083A5420 rotscale_table_empty, objc_grass_normal>
Code:
083A593C grass_tall: object_template <0xFFFF, 0x1005, unk_083A36F0, \
083A593C off_083A5938, stru_083A58F8, \
083A593C rotscale_table_empty, objc_grass_tall>The last entry in this structure is the callback that executed once every frame. Those are almost equal except for:
Code:
...
080DB46C BL complex_function
080DB470 LSLS R0, R0, #0x18
080DB472 CMP R0, #0
080DB474 BEQ loc_080DB48C
...
Code:
...
080DB71C BL put_0_into_r0_and_do_nothing
080DB720 LSLS R0, R0, #0x18
080DB722 CMP R0, #0
080DB724 BEQ loc_080DB73C
...To make the tall grass work, a function, equivalent to the one used in the function for normal grass, needs to be written at the same offset.
HOW TO FIX IT
Start overwriting at 08059f34 with 00 21 00 06 00 0e 02 28 01 d0 d1 28 01 d1 01 20 00 e0 00 20 00 21 70 47 03 28 f5 e7
eh 08059f34 0x2100
eh 08059f48 0x2100
eh 08059f4a 0x4770
eh 08059f4c 0x2803
eh 08059f4e 0xE7F5
Have fun and please credit me.
EDIT
If you want to enable the tiny grass too overwrite at 0805A0EC with 0C 30 09 E0. (It's mapped to behaviour byte 7)
Last edited:
