[Other] No trade evolutions

[Martyk]

Hello,
Im pretty new to this Decomp stuff but I would like to make it so that there are no more trade evolutions.
Obviously for pokemon such as golem, alakazam etc. this is no problem since I can just set the evolution type to EVO_LEVEL and set the desired level to whatever.
The problem comes in with the trade with items. I would like to make it so that you can use metal coat, upgrade, electirizer etc into items that you can use like evolution stones.

First thing I did was set the evolution types to EVO_ITEM corresponding to the correct item in

src\data\pokemon\evolution.h

Spoiler:

(Example)

[SPECIES_MAGMAR]	 = {{EVO_ITEM, ITEM_MAGMARIZER, SPECIES_MAGMORTAR}},

After this, I went to

src\data\items.h

and set the fieldUseFunction to ItemUseOutOfBattle_EvolutionStone

Spoiler:

[ITEM_DUBIOUS_DISC] =
    {
        .name = _("Dubious Disc"),
        .itemId = ITEM_DUBIOUS_DISC,
        .price = 2000,
        .description = sDubiousDiscDesc,
        .pocket = POCKET_ITEMS,
        .type = 4,
        .fieldUseFunc = ItemUseOutOfBattle_EvolutionStone,
        .secondaryId = 0,
    },

Next, I went to

src\data\pokemon\item_effects.h

and added all the items needed for trade evolutions to the list at the bottom of the file in the same structure as they do with the evolution stones.

Spoiler:

[ITEM_KINGS_ROCK - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_METAL_COAT - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_PROTECTOR - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_DRAGON_SCALE - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_ELECTIRIZER - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_MAGMARIZER - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_UP_GRADE - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_DUBIOUS_DISC - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_PRISM_SCALE - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_REAPER_CLOTH - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_DEEP_SEA_TOOTH - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_DEEP_SEA_SCALE - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_SACHET - ITEM_POTION] = gItemEffect_EvoStone,
	[ITEM_WHIPPED_DREAM - ITEM_POTION] = gItemEffect_EvoStone,

Now i am stuck. When i compile my rom at this point I can use the items but when I try using them the screen fades to black as if going to the Pokémon menu and that's it. so basically just a black screen.

I hope somebody can help me, or has done the "use trade evolution items" thing but in a different way, that might be able to explain how they did it.
Please explain it as if you are talking to a 5 year old since im quite new to all this.
Thanks in advance

 

[Sapphire Jester]

You are really close, there are just four two things you missed. First, in src\data\items.h, you need to change the type to be 1, as that is what the regular evolution stones use. So your dubious disk should look like this:

Spoiler:

[ITEM_DUBIOUS_DISC] =
    {
        .name = _("Dubious Disc"),
        .itemId = ITEM_DUBIOUS_DISC,
        .price = 2000,
        .description = sDubiousDiscDesc,
        .pocket = POCKET_ITEMS,
        [B].type = 1,[/B]
        .fieldUseFunc = ItemUseOutOfBattle_EvolutionStone,
        .secondaryId = 0,
    },

EDIT: I just realized you are using the Item expansion, so the below steps don't apply. If you were using regular emerald you would have to create separate item effects for each item entry, but with the item expansion you just use gItemEffect_EvoStone for each one. So for you, just ignore the spoiler tag.

Spoiler:

Second, there are two things you need to change with src\data\pokemon\item_effects.h. With this file there are two parts: item effects for each item that can be used from the bag, and a table to link those item effects to the item. First, you need to add the item effect, which can easily be done by copying the standard evolution stones and changing the name. Using the dubious disk as the example again, you should have something like this (the leaf stone is also shown for comparison):

Spoiler:

const u8 gItemEffect_LeafStone[6] = {
    [4] = ITEM4_EVO_STONE,
};

const u8 gItemEffect_DubiousDisk[6] = {
    [4] = ITEM4_EVO_STONE,
};

Third, you need to change the table, still in src\data\pokemon\item_effects.h. Each entry in the table needs to link to the item effect made on the top half of the file (notice how all the regular evolution stones have separate item effects on this table, not gItemEffect_EvoStone). So again, with Dubious Disk (Porygon Z getting a lot of love today):

Spoiler:

[ITEM_DUBIOUS_DISC - ITEM_POTION] = gItemEffect_DubiousDisk,

Finally, the last thing to worry about is item placement. include\constants\items.h has a line at the bottom that defines if an item will have an effect if used on a Pokemon. By default, this works on all items from potions to berries, and everything in between. Hold Items and Trade Items, in both regular emerald and using the item expansion, are beyond the slot for the last berry, so you need to change this to get the evolution item to work (without it, the pokemon will have their hp bar shown as if they can use the stone, but selecting them gives the 'this item will have no effect' message). For item expansion, you'll want to do this:

Spoiler:

#define ITEM_HAS_EFFECT(item) ((item) >= ITEM_POTION && (item) <= ITEM_GRASSY_SEED)

Do all this for each new item, and everything should work (I just tried it out all the same steps and got a Sandshrew to evolve into Sandslash with Soft Sand). Good luck!

 

[Martyk]

You are really close, there are just three one things you missed. First, in src\data\items.h, you need to change the type to be 1, as that is what the regular evolution stones use. So your dubious disk should look like this:

Spoiler:

[ITEM_DUBIOUS_DISC] =
    {
        .name = _("Dubious Disc"),
        .itemId = ITEM_DUBIOUS_DISC,
        .price = 2000,
        .description = sDubiousDiscDesc,
        .pocket = POCKET_ITEMS,
        [B].type = 1,[/B]
        .fieldUseFunc = ItemUseOutOfBattle_EvolutionStone,
        .secondaryId = 0,
    },

EDIT: I just realized you are using the Item expansion, so the below steps don't apply. If you were using regular emerald you would have to create separate item effects for each item entry, but with the item expansion you just use gItemEffect_EvoStone for each one. So for you, just ignore the spoiler tag.

Spoiler:

Second, there are two things you need to change with src\data\pokemon\item_effects.h. With this file there are two parts: item effects for each item that can be used from the bag, and a table to link those item effects to the item. First, you need to add the item effect, which can easily be done by copying the standard evolution stones and changing the name. Using the dubious disk as the example again, you should have something like this (the leaf stone is also shown for comparison):

Spoiler:

const u8 gItemEffect_LeafStone[6] = {
    [4] = ITEM4_EVO_STONE,
};

const u8 gItemEffect_DubiousDisk[6] = {
    [4] = ITEM4_EVO_STONE,
};

Finally, you need to change the table, still in src\data\pokemon\item_effects.h. Each entry in the table needs to link to the item effect made on the top half of the file (notice how all the regular evolution stones have separate item effects on this table, not gItemEffect_EvoStone). So again, with Dubious Disk (Porygon Z getting a lot of love today):

Spoiler:

[ITEM_DUBIOUS_DISC - ITEM_POTION] = gItemEffect_DubiousDisk,

Another thing to worry about is item placement. include\constants\items.h has a line at the bottom that defines if an item will have an effect if used on a Pokemon. By default, this works on all items from potions to berries, and everything in between. Hold Items and Trade Items, in both regular emerald and using the item expansion, are beyond the slot for the last berry, so you need to change this to get the evolution item to work (without it, the pokemon will have their hp bar shown as if they can use the stone, but selecting them gives the 'this item will have no effect' message). For item expansion, you'll want to do this:

Spoiler:

#define ITEM_HAS_EFFECT(item) ((item) >= ITEM_POTION && (item) <= ITEM_GRASSY_SEED)

Do all this for each new item, and everything should work (I just tried it out all the same steps and got a Sandshrew to evolve into Sandslash with Soft Sand). Good luck!

You are the best, thank you!