Rework dwarven as sea level tends to be a pretty useless number

src/main/java/slimeknights/tconstruct/tools/modifiers/traits/harvest/DwarvenModifier.java

@@ -21,36 +21,64 @@ public class DwarvenModifier extends Modifier {
   private static final Component MINING_SPEED = TConstruct.makeTranslation("modifier", "dwarven.mining_speed");
   /** Distance below sea level to get boost */
   private static final float BOOST_DISTANCE = 64f;
+  /** Blocks above 0 when debuff starts, and the range of debuff in the world */
+  private static final float DEBUFF_RANGE = 128f;
   /** Boost when at distance, gets larger when lower */
   private static final float BONUS = 6;
 
   /** Gets the boost for the given level and height, can go negative */
-  private static float getBoost(Level world, int y, int level) {
-    // prevent the modifier from getting too explosive in tall worlds, clamp between -6 and 12
-    float bonus = Mth.clamp((world.getSeaLevel() - y) / BOOST_DISTANCE, -1, 2);
-    // grants 0 bonus at sea level, -1x at BOOST_DISTANCE, 1x at -BOOST_DISTANCE, 2x at -2*BOOST_DISTANCE
-    return bonus * level * BONUS;
+  private static float getBoost(Level world, int y, int level, float baseSpeed, float modifier) {
+    // grants 0 bonus at 64, 1x at -BOOST_DISTANCE, 2x at -2*BOOST_DISTANCE
+    // prevents the modifier from getting too explosive in tall worlds, clamp between -6 and 12
+    if (y < BOOST_DISTANCE) {
+      float scale = Mth.clamp((BOOST_DISTANCE - y) / BOOST_DISTANCE, 0, 2);
+      return baseSpeed + (level * scale * BONUS * modifier);
+    }
+
+    // start the debuff 128 blocks below the top, but for short worlds start it 128 blocks above the full boost (so we have 64 blocks of neutral)
+    // in the overworld, debuff is between 320 and 128. In the nether, its between 256 and 128
+    // the method to get the world's sea level is not reliable, so just using absolute bounds of the world
+    float baselineDebuff = Math.max(world.getMaxBuildHeight() - (DEBUFF_RANGE + BOOST_DISTANCE), DEBUFF_RANGE);
+    if (y > baselineDebuff) {
+      // range of 64 blocks for the regular debuff, anything above is full debuff
+      if (y >= baselineDebuff + DEBUFF_RANGE) {
+        return baseSpeed * 0.25f;
+      }
+      // formula goes from 100% at baseline to 25% at baseline+128
+      return baseSpeed * (1 - ((y - baselineDebuff) / DEBUFF_RANGE * 0.75f));
+    }
+
+    // no boost, no debuff
+    return baseSpeed;
   }
 
   @Override
   public void onBreakSpeed(IToolStackView tool, int level, BreakSpeed event, Direction sideHit, boolean isEffective, float miningSpeedModifier) {
     if (!isEffective) {
       return;
     }
-    float boost = getBoost(event.getPlayer().level, event.getPos().getY(), level);
-    event.setNewSpeed(event.getNewSpeed() + (boost * miningSpeedModifier * tool.getMultiplier(ToolStats.MINING_SPEED)));
+    event.setNewSpeed(getBoost(event.getPlayer().level, event.getPos().getY(), level, event.getNewSpeed(), miningSpeedModifier * tool.getMultiplier(ToolStats.MINING_SPEED)));
   }
 
   @Override
   public void addInformation(IToolStackView tool, int level, @Nullable Player player, List<Component> tooltip, TooltipKey key, TooltipFlag tooltipFlag) {
     if (tool.hasTag(TinkerTags.Items.HARVEST)) {
       double boost;
       if (player != null && key == TooltipKey.SHIFT) {
-        boost = getBoost(player.level, (int)player.getY(), level);
+        // passing in 1 means greater than 1 is a boost, and less than 1 is a percentage
+        // the -1 means for percentage, the range is now 0 to -75%, and for flat boost its properly 0 to BOOST
+        boost = getBoost(player.level, (int)player.getY(), level, 1, 1f) - 1;
+        if (boost < 0) {
+          // goes from 0 to -75%, don't show 0%
+          if (boost <= -0.01) {
+            addPercentTooltip(MINING_SPEED, boost, tooltip);
+          }
+          return;
+        }
       } else {
         boost = BONUS * level;
       }
-      if (boost != 0) {
+      if (boost >= 0.01) {
         addFlatBoost(MINING_SPEED, boost * tool.getMultiplier(ToolStats.MINING_SPEED), tooltip);
       }
     }