[ASM & Hex] Changing OAM priority? (Fire Red)

[kobold]

Hi all,

I'm currently hacking weather and I'm attempting to improve how fog looks. Right now, fog only covers the bottom layers of tiles. If you've tried to use fog in Fire Red yourself you'll probably know what I'm talking about -

This is because the priority of the fog OAM is set to 2 (same as an NPC's overworld sprite) so it is covered by the top layers of tiles. Below is a screenshot of sandstorm, for comparison -

As you can see, the priority of the sandstorm OAM is set to 1 so it appears above the tops of trees and overworld sprites. If it is possible to change the priority of the fog OAM to 1, we could make fog look a whole lot better than it does currently. Does anyone know how OAMs function and how I could edit how they work? Though I have a feeling this might be impossible as fog graphics use transparency and others like rain and sandstorm do not.

Thought it was worth asking anyway though. Any help on OAMs in general is appreciated. Thank you!

 

[Blah]

Hi all,

I'm currently hacking weather and I'm attempting to improve how fog looks. Right now, fog only covers the bottom layers of tiles. If you've tried to use fog in Fire Red yourself you'll probably know what I'm talking about -

This is because the priority of the fog OAM is set to 2 (same as an NPC's overworld sprite) so it is covered by the top layers of tiles. Below is a screenshot of sandstorm, for comparison -

As you can see, the priority of the sandstorm OAM is set to 1 so it appears above the tops of trees and overworld sprites. If it is possible to change the priority of the fog OAM to 1, we could make fog look a whole lot better than it does currently. Does anyone know how OAMs function and how I could edit how they work? Though I have a feeling this might be impossible as fog graphics use transparency and others like rain and sandstorm do not.

Thought it was worth asking anyway though. Any help on OAMs in general is appreciated. Thank you!

Do you have any actual function addresses? Or the address for the fog weather graphic? I can help you if you provide either.

 

[kobold]

I think so - It looks like the fog weather routine is at 7C990. It's the function called by the weather_funcs table at 3C2BBC.

 

[Blah]

If this is the fog animation, changing 08 to 04 at 083C6731 should resolve the issue.

 

[Blah]

@FBI This causes everything to dissapear including the menue.

The text should still work and the fog should be above everything in an english FR rom. But you'll observe that the player and other overworlds are rendered invisible. This is because they're on the same OAM layer without the semi transparent flag enabled.