WIP fractal-gavoro-pseudoerosion

common/api/src/main/java/com/dfsek/terra/api/noise/DerivativeNoiseSampler.java

@@ -0,0 +1,22 @@
+package com.dfsek.terra.api.noise;
+
+/**
+ * A NoiseSampler which additionally provides directional derivatives
+ */
+public interface DerivativeNoiseSampler extends NoiseSampler {
+
+    static boolean providesDerivative(NoiseSampler sampler) {
+        if (sampler instanceof DerivativeNoiseSampler dSampler) {
+            return dSampler.isDerivable();
+        }
+        return false;
+    }
+
+    default boolean isDerivable()  {
+        return false;
+    }
+
+    double[] noised(long seed, double x, double y);
+    
+    double[] noised(long seed, double x, double y, double z);
+}