configurable blending distance

common/src/main/java/com/dfsek/terra/api/math/MathUtil.java

@@ -8,7 +8,9 @@ import java.util.Random;
 /**
  * Utility class for mathematical functions.
  */
-public class MathUtil {
+public final class MathUtil {
+    private static final double EPSILON = 0.1E-5;
+
     /**
      * Gets the standard deviation of an array of doubles.
      *
@@ -57,29 +59,13 @@ public class MathUtil {
     }
 
     /**
-     * Compute binary logarithm
+     * Compare 2 floating-point values with epsilon to account for rounding errors
      *
-     * @param bits Input
-     * @return Binary logarithm
+     * @param a Value 1
+     * @param b Value 2
+     * @return Whether these values are equal
      */
-    public static int binlog(int bits) {
-        int log = 0;
-        if((bits & 0xffff0000) != 0) {
-            bits >>>= 16;
-            log = 16;
-        }
-        if(bits >= 256) {
-            bits >>>= 8;
-            log += 8;
-        }
-        if(bits >= 16) {
-            bits >>>= 4;
-            log += 4;
-        }
-        if(bits >= 4) {
-            bits >>>= 2;
-            log += 2;
-        }
-        return log + (bits >>> 1);
+    public static boolean equals(double a, double b) {
+        return a == b || FastMath.abs(a - b) < EPSILON;
     }
 }

common/src/main/java/com/dfsek/terra/config/base/ConfigPackTemplate.java

@@ -4,9 +4,11 @@ import com.dfsek.tectonic.annotations.Default;
 import com.dfsek.tectonic.annotations.Value;
 import com.dfsek.tectonic.config.ValidatedConfigTemplate;
 import com.dfsek.tectonic.exception.ValidationException;
+import com.dfsek.terra.api.math.MathUtil;
 import com.dfsek.terra.biome.grid.master.TerraBiomeGrid;
 import com.dfsek.terra.generation.config.NoiseBuilder;
 import com.dfsek.terra.image.ImageLoader;
+import net.jafama.FastMath;
 
 import java.util.HashMap;
 import java.util.List;
@@ -51,6 +53,16 @@ public class ConfigPackTemplate implements ValidatedConfigTemplate {
     @Default
     private double blendAmp = 4.0D;
 
+    @Value("blend.terrain.base")
+    @Default
+    private int baseBlend = 4;
+
+
+    @Value("blend.terrain.elevation")
+    @Default
+    private int elevationBlend = 4;
+
+
     @Value("erode.enable")
     @Default
     private boolean erode = false;
@@ -243,12 +255,27 @@ public class ConfigPackTemplate implements ValidatedConfigTemplate {
         return imageLoader;
     }
 
+    public int getBaseBlend() {
+        return baseBlend;
+    }
+
+    public int getElevationBlend() {
+        return elevationBlend;
+    }
+
     @Override
     public boolean validate() throws ValidationException {
         if(gridType.equals(TerraBiomeGrid.Type.RADIAL) && internalGrid == null)
             throw new ValidationException("No internal BiomeGrid specified");
         if(biomeZChannel.equals(biomeXChannel) || zoneChannel.equals(biomeXChannel) || zoneChannel.equals(biomeZChannel))
             throw new ValidationException("2 objects share the same image channels: biome-x and biome-z");
+
+        if(!MathUtil.equals(FastMath.log(baseBlend) / FastMath.log(2d), FastMath.round(FastMath.log(baseBlend) / FastMath.log(2d)))) {
+            throw new ValidationException("Biome base blend value \"" + baseBlend + "\" is not a power of 2.");
+        }
+        if(!MathUtil.equals(FastMath.log(elevationBlend) / FastMath.log(2d), FastMath.round(FastMath.log(elevationBlend) / FastMath.log(2d)))) {
+            throw new ValidationException("Biome elevation blend value \"" + baseBlend + "\" is not a power of 2.");
+        }
         return true;
     }
 }

common/src/main/java/com/dfsek/terra/generation/MasterChunkGenerator.java

@@ -91,7 +91,7 @@ public class MasterChunkGenerator implements TerraChunkGenerator {
                 int xOrig = (chunkX << 4);
                 int zOrig = (chunkZ << 4);
 
-                Sampler sampler = new Sampler(chunkX, chunkZ, tw.getGrid(), world, 4, 8);
+                Sampler sampler = new Sampler(chunkX, chunkZ, tw.getGrid(), world, configPack.getTemplate().getElevationBlend(), configPack.getTemplate().getBaseBlend());
 
                 for(byte x = 0; x < 16; x++) {
                     for(byte z = 0; z < 16; z++) {