Try to make climate layer generation more robust (and catch an annoying bug)

src/main/java/biomesoplenty/common/world/BiomeProviderBOP.java

@@ -128,7 +128,7 @@ public class BiomeProviderBOP extends BiomeProvider
     }
         
     // superimpose hot and cold regions an a land and sea layer
-    public static GenLayer climateLayer(BOPWorldSettings settings, long worldSeed)
+    public static GenLayerClimate climateLayer(BOPWorldSettings settings, long worldSeed)
     {
         GenLayer temperature;
         switch(settings.tempScheme)
@@ -167,12 +167,12 @@ public class BiomeProviderBOP extends BiomeProvider
                 break;
         }
 
-        GenLayer climate = new GenLayerClimate(103L, temperature, rainfall);        
+        GenLayerClimate climate = new GenLayerClimate(103L, temperature, rainfall);
         // stack = new GenLayerEdge(3L, stack, GenLayerEdge.Mode.SPECIAL);
         return climate;
     }    
     
-    public static GenLayer allocateBiomes(long worldSeed, BOPWorldSettings settings, GenLayer mainBranch, GenLayer subBiomesInit, GenLayer climateLayer)
+    public static GenLayer allocateBiomes(long worldSeed, BOPWorldSettings settings, GenLayer mainBranch, GenLayer subBiomesInit, GenLayerClimate climateLayer)
     {        
         // allocate the basic biomes        
         GenLayer biomesLayer = new GenLayerBiomeBOP(200L, mainBranch, climateLayer, settings);
@@ -180,16 +180,16 @@ public class BiomeProviderBOP extends BiomeProvider
         // magnify everything (using the same seed)
         biomesLayer = new GenLayerZoom(1000L, biomesLayer);
         subBiomesInit = new GenLayerZoom(1000L, subBiomesInit);
-        climateLayer = new GenLayerZoom(1000L, climateLayer);
+        GenLayer climateLayerZoomed = new GenLayerZoom(1000L, climateLayer);
         
         // add medium islands
         switch(settings.landScheme)
         {
             case ARCHIPELAGO:
-                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayer, 4);
+                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayerZoomed, 4);
                 break;
             case CONTINENTS:
-                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayer, 60);
+                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayerZoomed, 60);
                 break;
             case VANILLA: default:
                 break;
@@ -198,7 +198,7 @@ public class BiomeProviderBOP extends BiomeProvider
         // magnify everything again (using the same seed)
         biomesLayer = new GenLayerZoom(1000L, biomesLayer);
         subBiomesInit = new GenLayerZoom(1000L, subBiomesInit);
-        climateLayer = new GenLayerZoom(1000L, climateLayer);
+        climateLayerZoomed = new GenLayerZoom(1000L, climateLayerZoomed);
         
         // add edge biomes
         biomesLayer = new GenLayerBiomeEdgeBOP(1000L, biomesLayer);
@@ -210,13 +210,13 @@ public class BiomeProviderBOP extends BiomeProvider
         switch(settings.landScheme)
         {
             case ARCHIPELAGO:
-                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayer, 8);
+                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayerZoomed, 8);
                 break;
             case CONTINENTS:
-                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayer, 60);
+                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayerZoomed, 60);
                 break;
             case VANILLA: default:
-                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayer, 12);
+                biomesLayer = new GenLayerBiomeIslands(15L, biomesLayer, climateLayerZoomed, 12);
                 break;
         }
         
@@ -242,7 +242,7 @@ public class BiomeProviderBOP extends BiomeProvider
         GenLayer riversAndSubBiomesInit = new GenLayerRiverInit(100L, mainBranch);
          
         // create climate layer
-        GenLayer climateLayer = climateLayer(settings, worldSeed);
+        GenLayerClimate climateLayer = climateLayer(settings, worldSeed);
         
         // allocate the biomes
         mainBranch = allocateBiomes(worldSeed, settings, mainBranch, riversAndSubBiomesInit, climateLayer);

src/main/java/biomesoplenty/common/world/layer/GenLayerBiomeBOP.java

@@ -23,9 +23,9 @@ public class GenLayerBiomeBOP extends BOPGenLayer
     
     private BOPWorldSettings settings;
     private GenLayer landMassLayer;
-    private GenLayer climateLayer;
+    private GenLayerClimate climateLayer;
     
-    public GenLayerBiomeBOP(long seed, GenLayer landMassLayer, GenLayer climateLayer, BOPWorldSettings settings)
+    public GenLayerBiomeBOP(long seed, GenLayer landMassLayer, GenLayerClimate climateLayer, BOPWorldSettings settings)
     {
         super(seed);
         this.landMassLayer = landMassLayer;
@@ -51,7 +51,18 @@ public class GenLayerBiomeBOP extends BOPGenLayer
                 int index = z + x * areaWidth;
                 this.initChunkSeed((long)(z + areaX), (long)(x + areaY));
                 int landSeaVal = landSeaValues[index];
-                BOPClimates climate = BOPClimates.lookup(climateValues[index]);
+                int climateOrdinal = climateValues[index];
+                
+                BOPClimates climate;
+                try {
+                    climate = BOPClimates.lookup(climateOrdinal);
+                } catch (java.lang.ArrayIndexOutOfBoundsException e) {
+                    // This shouldn't happen - but apparently it (rarely) does (https://github.com/Glitchfiend/BiomesOPlenty/issues/983)
+                    // If it does it means that something weird happened with the climate layer / lookup
+                    // Rethrow with hopefully a more useful message
+                    String msg = "Climate lookup failed climateOrdinal: " + climateOrdinal + " climate layer mapping: " + climateLayer.debugClimateMappingInts();
+                    throw new java.lang.RuntimeException(msg,e);
+                }
                 
                 // At this point, oceans and land have been assigned, and so have mushroom islands
                 if (landSeaVal == Biome.getIdForBiome(Biomes.DEEP_OCEAN))

src/main/java/biomesoplenty/common/world/layer/GenLayerClimate.java

@@ -1,5 +1,7 @@
 package biomesoplenty.common.world.layer;
 
+import java.util.Arrays;
+
 import biomesoplenty.api.enums.BOPClimates;
 import biomesoplenty.api.generation.BOPGenLayer;
 import net.minecraft.util.math.MathHelper;
@@ -28,13 +30,20 @@ public class GenLayerClimate extends BOPGenLayer {
 
         for (int i = 0; i < areaWidth * areaHeight; ++i)
         {
-            int index = (temperatureValues[i] * 12) + rainfallValues[i];
-
             // temperature values from 0 (cold) to 8 (hot) and rainfall values from 0 (wet) to 11 (dry), index is (temperatureValue * 12) + rainfallValue
-            // index is clamped to account for potential rounding errors due to use of doubles/floats
+            // clamp as a precaution against potential rounding errors due to use of doubles/floats in noise calculations
-            out[i] = this.climateMapping[MathHelper.clamp(index, 0, this.climateMapping.length - 1)];
+            // this guarantees index is between 0 and 108 (= 9 * 12), the range of indexes in BOPClimates.getClimateMappingInts()
+            int index = ( MathHelper.clamp(temperatureValues[i], 0, 8) * 12 ) + MathHelper.clamp(rainfallValues[i], 0, 11);
+            
+            out[i] = this.climateMapping[index];
         }
         return out;
     }
+    
+    // debug method added to assist in troubleshooting a specific bug (https://github.com/Glitchfiend/BiomesOPlenty/issues/983)
+    public String debugClimateMappingInts()
+    {
+        return Arrays.toString(this.climateMapping);
+    }
 
 }

src/main/java/biomesoplenty/common/world/layer/GenLayerTemperatureLatitude.java

@@ -48,7 +48,7 @@ public class GenLayerTemperatureLatitude extends BOPGenLayer
                 
                 this.initChunkSeed((long)X, (long)Y);
 
-                // set value between 1 and 4 which is periodic in Y (with some random variation)
+                // set value between 0 and 8 which is periodic in Y (with some random variation)
                 // ocean generally stays as ocean, unless it's ICY when it becomes frozen ocean
                 double Yoffset = Y + this.offset + ((this.nextInt(1001) - 500) * this.offsetVariation / 500.0D);
                 out[x + y * areaWidth] = MathHelper.floor(this.amplitude * Math.abs((Math.abs(Yoffset % period) - halfPeriod)));