z64me / z64playerRenderInit

supplemental to z64playas dynamic overlays

z64playerRenderInit

This OoT/MM mod allows functions to be embedded into and run from within player model files once per frame, enabling us to do fun effects like flowing capes, glowing materials, physics, scrolling textures, alternate costume/tunic models, HUD elements, and more.

Showcase

Prerequisites

• z64playas
• z64convert
• z64ovl or Sharp Ocarina
• Your z64playas manifest must use the POOL feature!

Building (z64ovl)

• Change the #includes to be for your specific version or game.
• Run make clean && make
• func.ovl and mod.bin are generated.

Building (Custom Actor Toolkit)

• This is how most people will use it.
• Adjust the #include in your source code to be for the game and version you're targeting.
• Use Custom Actor Toolkit to build func.c (it's super straightforward).
• func.ovl will be generated, which you then use in z64playas.

Warning

• The assembly at the start of func.c is a hacky way of trying to guarantee a jump to the renderinit function will be at the beginning of the overlay's .text section.
• It is very important that the beginning of the overlay's .text section be renderinit, or a jump to renderinit (see above).

OoT debug (bin/oot/debug)

• Write code_0xb8828.bin at 0xB4C828 (that is at 0xB8828 in code)
• Write 0C0355A2 at 0xB09264 (that is at 0x75264 in code)
• Write 0C0355A2 at 0xC1903C (that is at 0x17F8C in ovl_player_actor)
• Write 00000000 at 0xFE17FC (if using vanilla Adult Link) (that is at 0x57FC in his zobj)
• Write 00000000 at 0x10197FC (if using vanilla Young Link) (that is at 0x57FC in his zobj)

OoT NTSC 1.0 (bin/oot/ntsc10)

• Write code_0x9dac4.bin at 0xB24AC4 (that is at 0x9DAC4 in code)
• Write 0C02BAD9 at 0xAF2940 (that is at 0x6B940 in code)
• Write 0C02BAD9 at 0xBE5C4C (that is at 0x180DC in ovl_player_actor)
• Write 00000000 at 0xF8B7FC (if using vanilla Adult Link) (that is at 0x57FC in his zobj)
• Write 00000000 at 0xFC37FC (if using vanilla Young Link) (that is at 0x57FC in his zobj)

Using func.ovl once you've built or downloaded one

• func.ovl goes in the Dynamic ZOVL field in z64playas
• Make sure you have patched your game to be compatible with this tweak first using the instructions above.

How does it work? (a technical explanation)

This mod assumes a structure of this type resides at 0x57F8 in Link's 3D model file:

struct z64playerRenderInit
{
   /* offsets are relative to the start of Link's model in ram */
   uint32_t     start;           /* offset of start of overlay    */
   union
   {
      uint32_t  header;          /* offset of overlay header      */
      void      (*exec)(void*);  /* main routine after relocating */
   } u;
} *rinit;

Immediately before Link's drawing routine, the mod checks rinit->u.header. If its value is 0, no overlay is present. If it's a ram address, the function at that address is executed. Otherwise, the overlay described by rinit is relocated (a process which converts virtual ram addresses to physical ram addresses), and rinit->u.exec is updated to point to the main routine in the overlay.

In other words, this mod executes code stored in Link's 3D model file, of all places.

Why do it this way?

My approach is meant to maximize accessibility, portability, and ease of use: apply a very small patch to the game and you're ready to write code for your play-as mod. You don't have to worry about setting up your own hook, or injecting code, or hardware/Wii-VC compatibility, or porting (just change build targets). All the hard work is already done for you so you can focus on the fun part: being creative.

An additional benefit from using this implementation is that your play-as mods are automatically compatible with Ocarina of Time Online.

Special thanks

E-Gor, CrookedPoe: N64 hardware testing

Mikau6: Wii VC testing