[Question] Patching functions

[danielryb]

How should I approach patching functions?

For instance, I'd like to patch PlayerAction63 in overlays/actors/ovl_player_actor/z_player.c which is used during playing an instrument. I prototyped all the functions used inside the body, but when I compile the code, launch the game and take out the ocarina, it seems that the definitions for these functions aren't being used.

Here's my code:

#include "patches.h"

void Player_Action_88(Player* this, PlayState* play);
void func_808525C4(PlayState* play, Player* this);
void Player_TalkWithPlayer(PlayState* play, Actor* actor);
s32 Player_ActionChange_13(Player* this, PlayState* play);
void func_80836A5C(Player* this, PlayState* play);
void Player_AnimationPlayOnceReverse(PlayState* play, Player* this, PlayerAnimationHeader* anim);
s32 func_8085B28C(PlayState* play, Player* this, PlayerCsAction csAction);
void Player_SetAction_PreserveItemAction(PlayState* play, Player* this, PlayerActionFunc actionFunc, s32 arg3);
void func_8085255C(PlayState* play, Player* this);

// s32 func_8082DA90(PlayState* play);
s32 func_8082DA90(PlayState* play) { // this function has to be redefined to compile the project, and I'm not sure why.
    return (play->transitionTrigger != TRANS_TRIGGER_OFF) || (play->transitionMode != TRANS_MODE_OFF);
}

extern PlayerAnimationHeader* D_8085D17C[];

void Player_Action_63(Player* this, PlayState* play) {
    // @recomp Test hook.
    recomp_printf("TEST\n");

    if ((this->unk_AA5 != PLAYER_UNKAA5_4) && ((PlayerAnimation_Update(play, &this->skelAnime) &&
                                                (this->skelAnime.animation == D_8085D17C[this->transformation])) ||
                                               ((this->skelAnime.mode == 0) && (this->av2.actionVar2 == 0)))) {
        func_808525C4(play, this);
        if (!(this->actor.flags & ACTOR_FLAG_20000000) || (this->unk_A90->id == ACTOR_EN_ZOT)) {
            Message_DisplayOcarinaStaff(play, OCARINA_ACTION_FREE_PLAY);
        }
    } else if (this->av2.actionVar2 != 0) {
        if (play->msgCtx.ocarinaMode == OCARINA_MODE_END) {
            play->interfaceCtx.unk_222 = 0;
            CutsceneManager_Stop(play->playerCsIds[PLAYER_CS_ID_ITEM_OCARINA]);
            this->actor.flags &= ~ACTOR_FLAG_20000000;

            if ((this->talkActor != NULL) && (this->talkActor == this->unk_A90) && (this->unk_A94 >= 0.0f)) {
                Player_TalkWithPlayer(play, this->talkActor);
            } else if (this->tatlTextId < 0) {
                this->talkActor = this->tatlActor;
                this->tatlActor->textId = -this->tatlTextId;
                Player_TalkWithPlayer(play, this->talkActor);
            } else if (!Player_ActionChange_13(this, play)) {
                func_80836A5C(this, play);
                Player_AnimationPlayOnceReverse(play, this, D_8085D17C[this->transformation]);
            }
        } else {
            s32 var_v1 = (play->msgCtx.ocarinaMode >= OCARINA_MODE_WARP_TO_GREAT_BAY_COAST) &&
                         (play->msgCtx.ocarinaMode <= OCARINA_MODE_WARP_TO_ENTRANCE);
            s32 pad[2];

            if (var_v1 || (play->msgCtx.ocarinaMode == OCARINA_MODE_APPLY_SOT) ||
                (play->msgCtx.ocarinaMode == OCARINA_MODE_APPLY_DOUBLE_SOT) ||
                (play->msgCtx.ocarinaMode == OCARINA_MODE_APPLY_INV_SOT_FAST) ||
                (play->msgCtx.ocarinaMode == OCARINA_MODE_APPLY_INV_SOT_SLOW)) {
                if (play->msgCtx.ocarinaMode == OCARINA_MODE_APPLY_SOT) {
                    if (!func_8082DA90(play)) {
                        if (gSaveContext.save.saveInfo.playerData.threeDayResetCount == 1) {
                            play->nextEntrance = ENTRANCE(CUTSCENE, 1);
                        } else {
                            play->nextEntrance = ENTRANCE(CUTSCENE, 0);
                        }

                        gSaveContext.nextCutsceneIndex = 0xFFF7;
                        play->transitionTrigger = TRANS_TRIGGER_START;
                    }
                } else {
                    Actor* actor;

                    play->interfaceCtx.unk_222 = 0;
                    CutsceneManager_Stop(play->playerCsIds[PLAYER_CS_ID_ITEM_OCARINA]);
                    this->actor.flags &= ~ACTOR_FLAG_20000000;

                    actor = Actor_Spawn(&play->actorCtx, play, var_v1 ? ACTOR_EN_TEST7 : ACTOR_EN_TEST6,
                                        this->actor.world.pos.x, this->actor.world.pos.y, this->actor.world.pos.z, 0, 0,
                                        0, play->msgCtx.ocarinaMode);
                    if (actor != NULL) {
                        this->stateFlags1 &= ~PLAYER_STATE1_20000000;
                        this->csAction = PLAYER_CSACTION_NONE;
                        func_8085B28C(play, NULL, PLAYER_CSACTION_19);
                        this->stateFlags1 |= PLAYER_STATE1_10000000 | PLAYER_STATE1_20000000;
                    } else {
                        func_80836A5C(this, play);
                        Player_AnimationPlayOnceReverse(play, this, D_8085D17C[this->transformation]);
                    }
                }
            } else if ((play->msgCtx.ocarinaMode == OCARINA_MODE_EVENT) &&
                       (play->msgCtx.lastPlayedSong == OCARINA_SONG_ELEGY)) {
                play->interfaceCtx.unk_222 = 0;
                CutsceneManager_Stop(play->playerCsIds[PLAYER_CS_ID_ITEM_OCARINA]);

                this->actor.flags &= ~ACTOR_FLAG_20000000;
                Player_SetAction_PreserveItemAction(play, this, Player_Action_88, 0);
                this->stateFlags1 |= PLAYER_STATE1_10000000 | PLAYER_STATE1_20000000;
            } else if (this->unk_AA5 == PLAYER_UNKAA5_4) {
                f32 temp_fa0 = this->skelAnime.jointTable[PLAYER_LIMB_ROOT - 1].x;
                f32 temp_fa1 = this->skelAnime.jointTable[PLAYER_LIMB_ROOT - 1].z;
                f32 var_fv1;

                var_fv1 = sqrtf(SQ(temp_fa0) + SQ(temp_fa1));
                if (var_fv1 != 0.0f) {
                    var_fv1 = (var_fv1 - 100.0f) / var_fv1;
                    var_fv1 = CLAMP_MIN(var_fv1, 0.0f);
                }

                this->skelAnime.jointTable[PLAYER_LIMB_ROOT - 1].x = temp_fa0 * var_fv1;
                this->skelAnime.jointTable[PLAYER_LIMB_ROOT - 1].z = temp_fa1 * var_fv1;
            } else {
                func_8085255C(play, this);
            }
        }
    }
}

Are there any resources I could use to learn more on the topic?

[briaguya]

where did you try to add this code? i tried throwing it at the bottom of patches/input.c, checked RecompiledPatches/funcs.h and saw Player_Action_63 was added, and then pulled out the ocarina in game and saw a wall of "TEST" in the terminal output.

[danielryb]

I have it placed in a separate .c file in patches directory, and I achieve the same result. However, when you take out the instrument the game stops responding to input, and you can notice that Link's ocarina idle animation doesn't really play either.

[Reonu]

I have it placed in a separate .c file in patches directory, and I achieve the same result. However, when you take out the instrument the game stops responding to input, and you can notice that Link's ocarina idle animation doesn't really play either.

This is because you have to relocate the D_8085D17C variable for the function to work properly. Look for the text "Manual relocation" in order to find examples of this in the code.

Keep in mind that having to do manual relocations will not be a thing after the recompiler upgrades that Wiseguy is working on. He's making it so that relocations are automated.