Document thunderstorm

3 files changed, 111 insertions, 78 deletions

diff --git a/include/field_weather.h b/include/field_weather.h
index 894c661be..48118c9a6 100644
--- a/include/field_weather.h
+++ b/include/field_weather.h
@@ -46,11 +46,11 @@ struct Weather
     u8 gammaStepDelay;
     u8 gammaStepFrameCounter;
     u16 fadeDestColor;
-    /*0x6C6*/ u8 palProcessingState;
-    /*0x6C7*/ u8 fadeScreenCounter;
-    /*0x6C8*/ bool8 readyForInit;
-    /*0x6C9*/ u8 taskId;
-    /*0x6CA*/ u8 unknown_6CA;
+    u8 palProcessingState;
+    u8 fadeScreenCounter;
+    bool8 readyForInit;
+    u8 taskId;
+    u8 unknown_6CA;
     u8 unknown_6CB;
     u16 initStep;
     u16 finishStep;
@@ -60,6 +60,7 @@ struct Weather
     bool8 weatherChangeComplete;
     u8 weatherPicSpritePalIndex;
     u8 altGammaSpritePalIndex;
+    // Rain
     u16 rainSpriteVisibleCounter;
     u8 curRainSpriteIndex;
     u8 targetRainSpriteCount;
@@ -67,37 +68,41 @@ struct Weather
     u8 rainSpriteVisibleDelay;
     u8 isDownpour;
     u8 rainStrength;
-    /*0x6DE*/ u8 cloudSpritesCreated;
-    u8 filler_6DF[1];
+    u8 cloudSpritesCreated;
+    // Snow
     u16 snowflakeVisibleCounter;
     u16 unknown_6E2;
     u8 snowflakeSpriteCount;
     u8 targetSnowflakeSpriteCount;
-    u16 unknown_6E6;
+    // Thunderstorm
+    u16 thunderDelay;
     u16 thunderCounter;
-    u8 unknown_6EA;
-    u8 unknown_6EB;
-    u8 unknown_6EC;
-    u8 thunderTriggered;
+    bool8 thunderAllowEnd;
+    bool8 thunderSkipShort;
+    u8 thunderShortRetries;
+    bool8 thunderTriggered;
+    // Horizontal fog
     u16 fogHScrollPosX;
     u16 fogHScrollCounter;
     u16 fogHScrollOffset;
     u8 lightenedFogSpritePals[6];
     u8 lightenedFogSpritePalsCount;
     u8 fogHSpritesCreated;
+    // Ash
     u16 ashBaseSpritesX;
     u16 unknown_6FE;
     u8 ashSpritesCreated;
-    u8 filler_701[3];
+    // Sandstorm
     u32 sandstormXOffset;
     u32 sandstormYOffset;
-    u8 filler_70C[2];
+    u16 sandstormUnused;
     u16 sandstormBaseSpritesX;
     u16 sandstormPosY;
     u16 sandstormWaveIndex;
     u16 sandstormWaveCounter;
     u8 sandstormSpritesCreated;
     u8 sandstormSwirlSpritesCreated;
+    // Diagonal fog
     u16 fogDBaseSpritesX;
     u16 fogDPosY;
     u16 fogDScrollXCounter;
@@ -105,13 +110,13 @@ struct Weather
     u16 fogDXOffset;
     u16 fogDYOffset;
     u8 fogDSpritesCreated;
-    u8 filler_725[1];
+    // Bubbles
     u16 bubblesDelayCounter;
     u16 bubblesDelayIndex;
     u16 bubblesCoordsIndex;
     u16 bubblesSpriteCount;
     u8 bubblesSpritesCreated;
-    u8 filler_72F;
+
     u16 currBlendEVA;
     u16 currBlendEVB;
     u16 targetBlendEVA;
@@ -119,12 +124,12 @@ struct Weather
     u8 blendUpdateCounter;
     u8 blendFrameCounter;
     u8 blendDelay;
-    u8 filler_73B[0x3C-0x3B];
+    // Drought
     s16 droughtBrightnessStage;
     s16 droughtLastBrightnessStage;
     s16 droughtTimer;
     s16 droughtState;
-    u8 filler_744[0xD-4];
+    u8 droughtUnused[9];
     s8 loadDroughtPalsIndex;
     u8 loadDroughtPalsOffset;
 };
@@ -141,7 +146,7 @@ void StartWeather(void);
 void SetNextWeather(u8 weather);
 void SetCurrentAndNextWeather(u8 weather);
 void SetCurrentAndNextWeatherNoDelay(u8 weather);
-void sub_80ABC48(s8 gammaIndex);
+void ApplyWeatherGammaShiftIfIdle(s8 gammaIndex);
 void sub_80ABC7C(u8 gammaIndex, u8 gammaTargetIndex, u8 gammaStepDelay);
 void FadeScreen(u8 mode, s8 delay);
 bool8 IsWeatherNotFadingIn(void);
diff --git a/src/field_weather.c b/src/field_weather.c
index 331f0be78..67051377c 100644
--- a/src/field_weather.c
+++ b/src/field_weather.c
@@ -710,7 +710,7 @@ static bool8 LightenSpritePaletteInFog(u8 paletteIndex)
     return FALSE;
 }
 
-void sub_80ABC48(s8 gammaIndex)
+void ApplyWeatherGammaShiftIfIdle(s8 gammaIndex)
 {
     if (gWeatherPtr->palProcessingState == WEATHER_PAL_STATE_IDLE)
     {
@@ -728,7 +728,7 @@ void sub_80ABC7C(u8 gammaIndex, u8 gammaTargetIndex, u8 gammaStepDelay)
         gWeatherPtr->gammaTargetIndex = gammaTargetIndex;
         gWeatherPtr->gammaStepFrameCounter = 0;
         gWeatherPtr->gammaStepDelay = gammaStepDelay;
-        sub_80ABC48(gammaIndex);
+        ApplyWeatherGammaShiftIfIdle(gammaIndex);
     }
 }
 
@@ -887,7 +887,7 @@ bool8 LoadDroughtWeatherPalettes(void)
 
 static void SetDroughtGamma(s8 gammaIndex)
 {
-    sub_80ABC48(-gammaIndex - 1);
+    ApplyWeatherGammaShiftIfIdle(-gammaIndex - 1);
 }
 
 void DroughtStateInit(void)
diff --git a/src/field_weather_effect.c b/src/field_weather_effect.c
index b8a09faad..1069bc9a2 100644
--- a/src/field_weather_effect.c
+++ b/src/field_weather_effect.c
@@ -677,7 +677,7 @@ static bool8 CreateRainSprite(void)
 
     if (spriteId != MAX_SPRITES)
     {
-        gSprites[spriteId].tActive = 0;
+        gSprites[spriteId].tActive = FALSE;
         gSprites[spriteId].tRandom = spriteIndex * 145;
         while (gSprites[spriteId].tRandom >= 600)
             gSprites[spriteId].tRandom -= 600;
@@ -722,12 +722,12 @@ static bool8 UpdateVisibleRainSprites(void)
         gWeatherPtr->rainSpriteVisibleCounter = 0;
         if (gWeatherPtr->curRainSpriteIndex < gWeatherPtr->targetRainSpriteCount)
         {
-            gWeatherPtr->sprites.s1.rainSprites[gWeatherPtr->curRainSpriteIndex++]->tActive = 1;
+            gWeatherPtr->sprites.s1.rainSprites[gWeatherPtr->curRainSpriteIndex++]->tActive = TRUE;
         }
         else
         {
             gWeatherPtr->curRainSpriteIndex--;
-            gWeatherPtr->sprites.s1.rainSprites[gWeatherPtr->curRainSpriteIndex]->tActive = 0;
+            gWeatherPtr->sprites.s1.rainSprites[gWeatherPtr->curRainSpriteIndex]->tActive = FALSE;
             gWeatherPtr->sprites.s1.rainSprites[gWeatherPtr->curRainSpriteIndex]->invisible = TRUE;
         }
     }
@@ -1011,9 +1011,32 @@ static void UpdateSnowflakeSprite(struct Sprite *sprite)
 // WEATHER_RAIN_THUNDERSTORM
 //------------------------------------------------------------------------------
 
+enum {
+    // This block of states is run only once
+    // when first setting up the thunderstorm
+    TSTORM_STATE_LOAD_RAIN,
+    TSTORM_STATE_CREATE_RAIN,
+    TSTORM_STATE_INIT_RAIN,
+    TSTORM_STATE_WAIT_CHANGE,
+
+    // The thunderstorm loops through these states,
+    // not necessarily in order.
+    TSTORM_STATE_LOOP_START,
+    TSTORM_STATE_LOOP_WAIT,
+    TSTORM_STATE_INIT_THUNDER_SHORT_1,
+    TSTORM_STATE_INIT_THUNDER_SHORT_2,
+    TSTORM_STATE_TRY_THUNDER_SHORT,
+    TSTORM_STATE_TRY_NEW_THUNDER,
+    TSTORM_STATE_WAIT_THUNDER_SHORT,
+    TSTORM_STATE_INIT_THUNDER_LONG,
+    TSTORM_STATE_WAIT_THUNDER_LONG,
+    TSTORM_STATE_FADE_THUNDER_LONG,
+    TSTORM_STATE_END_THUNDER_LONG,
+};
+
 void Thunderstorm_InitVars(void)
 {
-    gWeatherPtr->initStep = 0;
+    gWeatherPtr->initStep = TSTORM_STATE_LOAD_RAIN;
     gWeatherPtr->weatherGfxLoaded = FALSE;
     gWeatherPtr->rainSpriteVisibleCounter = 0;
     gWeatherPtr->rainSpriteVisibleDelay = 4;
@@ -1022,7 +1045,7 @@ void Thunderstorm_InitVars(void)
     gWeatherPtr->gammaTargetIndex = 3;
     gWeatherPtr->gammaStepDelay = 20;
     gWeatherPtr->weatherGfxLoaded = FALSE;  // duplicate assignment
-    gWeatherPtr->thunderTriggered = 0;
+    gWeatherPtr->thunderTriggered = FALSE;
     SetRainStrengthFromSoundEffect(SE_THUNDERSTORM);
 }
 
@@ -1042,7 +1065,7 @@ static void SetThunderCounter(u16);
 
 void Downpour_InitVars(void)
 {
-    gWeatherPtr->initStep = 0;
+    gWeatherPtr->initStep = TSTORM_STATE_LOAD_RAIN;
     gWeatherPtr->weatherGfxLoaded = FALSE;
     gWeatherPtr->rainSpriteVisibleCounter = 0;
     gWeatherPtr->rainSpriteVisibleDelay = 4;
@@ -1066,100 +1089,105 @@ void Thunderstorm_Main(void)
     UpdateThunderSound();
     switch (gWeatherPtr->initStep)
     {
-    case 0:
+    case TSTORM_STATE_LOAD_RAIN:
         LoadRainSpriteSheet();
         gWeatherPtr->initStep++;
         break;
-    case 1:
+    case TSTORM_STATE_CREATE_RAIN:
         if (!CreateRainSprite())
             gWeatherPtr->initStep++;
         break;
-    case 2:
+    case TSTORM_STATE_INIT_RAIN:
         if (!UpdateVisibleRainSprites())
         {
             gWeatherPtr->weatherGfxLoaded = TRUE;
             gWeatherPtr->initStep++;
         }
         break;
-    case 3:
+    case TSTORM_STATE_WAIT_CHANGE:
         if (gWeatherPtr->palProcessingState != WEATHER_PAL_STATE_CHANGING_WEATHER)
-            gWeatherPtr->initStep = 6;
+            gWeatherPtr->initStep = TSTORM_STATE_INIT_THUNDER_SHORT_1;
         break;
-    case 4:
-        gWeatherPtr->unknown_6EA = 1;
-        gWeatherPtr->unknown_6E6 = (Random() % 360) + 360;
+    case TSTORM_STATE_LOOP_START:
+        gWeatherPtr->thunderAllowEnd = TRUE;
+        gWeatherPtr->thunderDelay = (Random() % 360) + 360;
         gWeatherPtr->initStep++;
         // fall through
-    case 5:
-        if (--gWeatherPtr->unknown_6E6 == 0)
+    case TSTORM_STATE_LOOP_WAIT:
+        // Wait between 360-720 frames before trying thunder again
+        if (--gWeatherPtr->thunderDelay == 0)
             gWeatherPtr->initStep++;
         break;
-    case 6:
-        gWeatherPtr->unknown_6EA = 1;
-        gWeatherPtr->unknown_6EB = Random() % 2;
+    case TSTORM_STATE_INIT_THUNDER_SHORT_1:
+        gWeatherPtr->thunderAllowEnd = TRUE;
+        gWeatherPtr->thunderSkipShort = Random() % 2;
         gWeatherPtr->initStep++;
         break;
-    case 7:
-        gWeatherPtr->unknown_6EC = (Random() & 1) + 1;
+    case TSTORM_STATE_INIT_THUNDER_SHORT_2:
+        gWeatherPtr->thunderShortRetries = (Random() & 1) + 1;
         gWeatherPtr->initStep++;
         // fall through
-    case 8:
-        sub_80ABC48(19);
-        if (gWeatherPtr->unknown_6EB == 0 && gWeatherPtr->unknown_6EC == 1)
-            SetThunderCounter(20);
+    case TSTORM_STATE_TRY_THUNDER_SHORT:
+        ApplyWeatherGammaShiftIfIdle(19);
+        if (!gWeatherPtr->thunderSkipShort && gWeatherPtr->thunderShortRetries == 1)
+            SetThunderCounter(20); // Do short thunder
 
-        gWeatherPtr->unknown_6E6 = (Random() % 3) + 6;
+        gWeatherPtr->thunderDelay = (Random() % 3) + 6;
         gWeatherPtr->initStep++;
         break;
-    case 9:
-        if (--gWeatherPtr->unknown_6E6 == 0)
+    case TSTORM_STATE_TRY_NEW_THUNDER:
+        if (--gWeatherPtr->thunderDelay == 0)
         {
-            sub_80ABC48(3);
-            gWeatherPtr->unknown_6EA = 1;
-            if (--gWeatherPtr->unknown_6EC != 0)
+            ApplyWeatherGammaShiftIfIdle(3);
+            gWeatherPtr->thunderAllowEnd = TRUE;
+            if (--gWeatherPtr->thunderShortRetries != 0)
             {
-                gWeatherPtr->unknown_6E6 = (Random() % 16) + 60;
-                gWeatherPtr->initStep = 10;
+                // Try a short thunder again
+                gWeatherPtr->thunderDelay = (Random() % 16) + 60;
+                gWeatherPtr->initStep = TSTORM_STATE_WAIT_THUNDER_SHORT;
             }
-            else if (gWeatherPtr->unknown_6EB == 0)
+            else if (!gWeatherPtr->thunderSkipShort)
             {
-                gWeatherPtr->initStep = 4;
+                // No more thunder, restart loop
+                gWeatherPtr->initStep = TSTORM_STATE_LOOP_START;
             }
             else
             {
-                gWeatherPtr->initStep = 11;
+                // Set up long thunder
+                gWeatherPtr->initStep = TSTORM_STATE_INIT_THUNDER_LONG;
             }
         }
         break;
-    case 10:
-        if (--gWeatherPtr->unknown_6E6 == 0)
-            gWeatherPtr->initStep = 8;
+    case TSTORM_STATE_WAIT_THUNDER_SHORT:
+        if (--gWeatherPtr->thunderDelay == 0)
+            gWeatherPtr->initStep = TSTORM_STATE_TRY_THUNDER_SHORT;
         break;
-    case 11:
-        gWeatherPtr->unknown_6E6 = (Random() % 16) + 60;
+    case TSTORM_STATE_INIT_THUNDER_LONG:
+        gWeatherPtr->thunderDelay = (Random() % 16) + 60;
         gWeatherPtr->initStep++;
         break;
-    case 12:
-        if (--gWeatherPtr->unknown_6E6 == 0)
+    case TSTORM_STATE_WAIT_THUNDER_LONG:
+        if (--gWeatherPtr->thunderDelay == 0)
         {
+            // Do long thunder
             SetThunderCounter(100);
-            sub_80ABC48(19);
-            gWeatherPtr->unknown_6E6 = (Random() & 0xF) + 30;
+            ApplyWeatherGammaShiftIfIdle(19);
+            gWeatherPtr->thunderDelay = (Random() & 0xF) + 30;
             gWeatherPtr->initStep++;
         }
         break;
-    case 13:
-        if (--gWeatherPtr->unknown_6E6 == 0)
+    case TSTORM_STATE_FADE_THUNDER_LONG:
+        if (--gWeatherPtr->thunderDelay == 0)
         {
             sub_80ABC7C(19, 3, 5);
             gWeatherPtr->initStep++;
         }
         break;
-    case 14:
+    case TSTORM_STATE_END_THUNDER_LONG:
         if (gWeatherPtr->palProcessingState == WEATHER_PAL_STATE_IDLE)
         {
-            gWeatherPtr->unknown_6EA = 1;
-            gWeatherPtr->initStep = 4;
+            gWeatherPtr->thunderAllowEnd = TRUE;
+            gWeatherPtr->initStep = TSTORM_STATE_LOOP_START;
         }
         break;
     }
@@ -1170,12 +1198,12 @@ bool8 Thunderstorm_Finish(void)
     switch (gWeatherPtr->finishStep)
     {
     case 0:
-        gWeatherPtr->unknown_6EA = 0;
+        gWeatherPtr->thunderAllowEnd = FALSE;
         gWeatherPtr->finishStep++;
         // fall through
     case 1:
         Thunderstorm_Main();
-        if (gWeatherPtr->unknown_6EA)
+        if (gWeatherPtr->thunderAllowEnd)
         {
             if (gWeatherPtr->nextWeather == WEATHER_RAIN
              || gWeatherPtr->nextWeather == WEATHER_RAIN_THUNDERSTORM
@@ -1203,16 +1231,16 @@ bool8 Thunderstorm_Finish(void)
 
 static void SetThunderCounter(u16 max)
 {
-    if (gWeatherPtr->thunderTriggered == 0)
+    if (!gWeatherPtr->thunderTriggered)
     {
         gWeatherPtr->thunderCounter = Random() % max;
-        gWeatherPtr->thunderTriggered = 1;
+        gWeatherPtr->thunderTriggered = TRUE;
     }
 }
 
 static void UpdateThunderSound(void)
 {
-    if (gWeatherPtr->thunderTriggered == 1)
+    if (gWeatherPtr->thunderTriggered == TRUE)
     {
         if (gWeatherPtr->thunderCounter == 0)
         {
@@ -1224,7 +1252,7 @@ static void UpdateThunderSound(void)
             else
                 PlaySE(SE_THUNDER2);
 
-            gWeatherPtr->thunderTriggered = 0;
+            gWeatherPtr->thunderTriggered = FALSE;
         }
         else
         {