Trimmed height pipeline work

- Removed the unused decoration, derivative and identity streams and Engine.getBiomeID
- Skipped the shore-height noise when a column sits outside the proven shore band
- Dropped interpolator groups whose bounds are zero in every base-capable biome

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexContributingGroupsTest.java

@@ -0,0 +1,85 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.biome.IrisBiomeGeneratorLink;
+import art.arcane.iris.generation.noise.IrisGenerator;
+import art.arcane.iris.generation.noise.IrisInterpolator;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.interpolation.InterpolationMethod;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+
+public class IrisComplexContributingGroupsTest {
+    @Test
+    public void groupsWithZeroBoundsInEveryBaseBiomeAreDropped() {
+        IrisComplex.GeneratorGroup flat = group(InterpolationMethod.BILINEAR_STARCAST_6, 7D, "default");
+        IrisComplex.GeneratorGroup hills = group(InterpolationMethod.BILINEAR_STARCAST_9, 12D, "hills", "cliffs");
+        IrisComplex.GeneratorGroup shoreOnly = group(InterpolationMethod.BILINEAR_STARCAST_3, 30D, "ocean");
+        IrisBiome plains = biome(link("default", 0, 0), link("hills", -4, 12));
+        IrisBiome desert = biome(link("default", 0, 0), link("cliffs", 0, 3));
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{flat, hills, shoreOnly}, List.of(plains, desert));
+
+        assertEquals(1, contributing.length);
+        assertSame(hills, contributing[0]);
+    }
+
+    @Test
+    public void aNegativeOnlyOrMaximumOnlyLinkKeepsItsGroup() {
+        IrisComplex.GeneratorGroup sinks = group(InterpolationMethod.BILINEAR, 16D, "sinks");
+        IrisComplex.GeneratorGroup peaks = group(InterpolationMethod.STARCAST_12, 42D, "peaks");
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{sinks, peaks},
+                List.of(biome(link("sinks", -6, 0)), biome(link("peaks", 0, 9))));
+
+        assertEquals(2, contributing.length);
+        assertSame(sinks, contributing[0]);
+        assertSame(peaks, contributing[1]);
+    }
+
+    @Test
+    public void linksThatCancelAcrossGeneratorsSumToZeroBoundsAndAreDropped() {
+        IrisComplex.GeneratorGroup pair = group(InterpolationMethod.BILINEAR_STARCAST_9, 52D, "rise", "fall");
+
+        IrisComplex.GeneratorGroup[] contributing = IrisComplex.contributingGroups(
+                new IrisComplex.GeneratorGroup[]{pair},
+                List.of(biome(link("rise", -5, 5), link("fall", 5, -5))));
+
+        assertEquals(0, contributing.length);
+    }
+
+    @Test
+    public void noBaseBiomesDropsEveryGroup() {
+        IrisComplex.GeneratorGroup hills = group(InterpolationMethod.BILINEAR_STARCAST_9, 12D, "hills");
+
+        assertEquals(0, IrisComplex.contributingGroups(new IrisComplex.GeneratorGroup[]{hills}, List.of()).length);
+    }
+
+    private static IrisComplex.GeneratorGroup group(InterpolationMethod function, double scale, String... keys) {
+        IrisInterpolator interpolator = new IrisInterpolator().setFunction(function).setHorizontalScale(scale);
+        IrisGenerator[] generators = new IrisGenerator[keys.length];
+        for (int index = 0; index < keys.length; index++) {
+            IrisGenerator generator = new IrisGenerator();
+            generator.setLoadKey(keys[index]);
+            generator.setInterpolator(interpolator);
+            generators[index] = generator;
+        }
+        return new IrisComplex.GeneratorGroup(interpolator, generators);
+    }
+
+    private static IrisBiome biome(IrisBiomeGeneratorLink... links) {
+        IrisBiome biome = new IrisBiome();
+        biome.setGenerators(new KList<>(List.of(links)));
+        return biome;
+    }
+
+    private static IrisBiomeGeneratorLink link(String generator, int min, int max) {
+        return new IrisBiomeGeneratorLink().setGenerator(generator).setMin(min).setMax(max);
+    }
+}

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexShoreBandTest.java

@@ -0,0 +1,207 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.biome.IrisBiome;
+import art.arcane.iris.generation.terrain.IrisRegion;
+import art.arcane.volmlib.util.collection.KList;
+import art.arcane.volmlib.util.noise.CNG;
+import art.arcane.volmlib.util.noise.OffsetNoiseGenerator;
+import art.arcane.volmlib.util.noise.SimplexNoise;
+import art.arcane.volmlib.util.stream.ProceduralStream;
+import org.junit.Test;
+
+import java.util.SplittableRandom;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.anyDouble;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.withSettings;
+
+public class IrisComplexShoreBandTest {
+    private static final double[] SHORE_EXTREMES = {0D, 1.2D, 3.2D, 2.5D, 7.75D, -1.5D, 4D, 0.0001D, 63.9D};
+
+    @Test
+    public void shoreHeightGeneratorIsAnIdentityPostSimplexSignature() {
+        for (int sample = 0; sample < 8; sample++) {
+            CNG generator = region(sample).getShoreHeightGenerator();
+            assertTrue(generator.getGenerator() instanceof OffsetNoiseGenerator);
+            assertTrue(((OffsetNoiseGenerator) generator.getGenerator()).getBase() instanceof SimplexNoise);
+            assertEquals(1D, generator.getOpacity(), 0D);
+            assertTrue(generator.getChildren() == null || generator.getChildren().isEmpty());
+            assertEquals(1D, generator.getPower(), 0D);
+            assertEquals(0D, generator.getUp(), 0D);
+            assertEquals(0D, generator.getDown(), 0D);
+            assertEquals(1D, generator.getPatch(), 0D);
+            assertNull(generator.getCache());
+            assertNull(generator.getCustomGenerator());
+        }
+    }
+
+    @Test
+    public void simplexAmplitudeBoundFitsInsideTheShoreNoiseRange() {
+        double kernelPeak = 0D;
+        for (int step = 0; step <= 2_000_000; step++) {
+            double radius = Math.sqrt(0.5D) * step / 2_000_000D;
+            double falloff = 0.5D - radius * radius;
+            kernelPeak = Math.max(kernelPeak, falloff * falloff * falloff * falloff * Math.sqrt(2D) * radius);
+        }
+        assertEquals(256D / 19683D, kernelPeak, 1e-9D);
+        double amplitude = 50D * 3D * 256D / 19683D;
+        assertTrue(0.5D + amplitude / 2D < IrisComplex.SHORE_NOISE_HIGHEST);
+        assertTrue(0.5D - amplitude / 2D > IrisComplex.SHORE_NOISE_LOWEST);
+    }
+
+    @Test
+    public void shoreHeightNoiseStaysInsideTheProvenRange() {
+        SplittableRandom random = new SplittableRandom(1337L);
+        double lowest = Double.POSITIVE_INFINITY;
+        double highest = Double.NEGATIVE_INFINITY;
+        for (int sample = 0; sample < 4; sample++) {
+            CNG generator = region(sample).getShoreHeightGenerator();
+            for (int point = 0; point < 250_000; point++) {
+                double scale = point % 2 == 0 ? 1D : 64D;
+                double noise = generator.noise(random.nextDouble(-1e6D, 1e6D) / scale, random.nextDouble(-1e6D, 1e6D) / scale);
+                lowest = Math.min(lowest, noise);
+                highest = Math.max(highest, noise);
+            }
+        }
+        assertTrue("lowest " + lowest, lowest >= IrisComplex.SHORE_NOISE_LOWEST);
+        assertTrue("highest " + highest, highest <= IrisComplex.SHORE_NOISE_HIGHEST);
+    }
+
+    @Test
+    public void lazyShoreBandMatchesTheEagerBandTop() {
+        SplittableRandom random = new SplittableRandom(42L);
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 2D);
+        for (int sample = 0; sample < 400_000; sample++) {
+            IrisRegion region = region(random.nextInt(64))
+                    .setShoreHeightMin(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightMax(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightZoom(random.nextBoolean() ? 3.14D : 0.15D)
+                    .setShoreMinimumWidth(random.nextInt(8) == 0 ? 2D : 0D);
+            double fluid = random.nextInt(4) == 0 ? 63D : random.nextInt(-64, 200);
+            double height = random.nextInt(3) == 0
+                    ? fluid + random.nextDouble(-3D, 9D)
+                    : random.nextInt(-64, 320) + (random.nextBoolean() ? 0D : random.nextDouble());
+            double x = random.nextInt(-30_000_000, 30_000_000);
+            double z = random.nextInt(-30_000_000, 30_000_000);
+            boolean eager = height > IrisComplex.shoreBandTop(height, region, x, z, fluid, slopes);
+            assertEquals(eager, IrisComplex.aboveShoreBand(height, region, x, z, fluid, slopes));
+        }
+    }
+
+    @Test
+    public void lazySurfaceBiomeMatchesTheEagerSelection() {
+        SplittableRandom random = new SplittableRandom(7L);
+        IrisBiome land = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome sea = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome shore = mock(IrisBiome.class, withSettings().stubOnly());
+        IrisBiome[] bases = new IrisBiome[8];
+        for (int flags = 0; flags < bases.length; flags++) {
+            IrisBiome base = mock(IrisBiome.class, withSettings().stubOnly());
+            doReturn((flags & 1) != 0).when(base).isShore();
+            doReturn((flags & 2) != 0).when(base).isLand();
+            doReturn((flags & 4) != 0).when(base).isAquatic();
+            bases[flags] = base;
+        }
+        ProceduralStream<IrisBiome> lands = constant(land);
+        ProceduralStream<IrisBiome> seas = constant(sea);
+        ProceduralStream<IrisBiome> shores = constant(shore);
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 4D);
+        for (int sample = 0; sample < 200_000; sample++) {
+            IrisRegion region = region(random.nextInt(16))
+                    .setShoreHeightMin(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreHeightMax(SHORE_EXTREMES[random.nextInt(SHORE_EXTREMES.length)])
+                    .setShoreMinimumWidth(random.nextInt(8) == 0 ? 3D : 0D);
+            double fluid = 63D;
+            double height = random.nextBoolean() ? fluid + random.nextInt(-3, 8) : random.nextInt(-64, 320);
+            double x = random.nextInt(-100_000, 100_000);
+            double z = random.nextInt(-100_000, 100_000);
+            IrisBiome base = bases[random.nextInt(bases.length)];
+            IrisBiome expected = eagerSurfaceBiome(height, base, region, x, z, fluid, lands, seas, shores, slopes);
+            assertSame(expected, IrisComplex.resolveSurfaceBiome(height, base, region, x, z, fluid, lands, seas, shores, slopes));
+        }
+    }
+
+    @Test
+    public void columnsOutsideTheShoreWindowNeverSampleTheShoreNoise() {
+        IrisRegion region = mock(IrisRegion.class);
+        doReturn(1.2D).when(region).getShoreHeightMin();
+        doReturn(3.2D).when(region).getShoreHeightMax();
+        doReturn(0D).when(region).getShoreMinimumWidth();
+        doThrow(new AssertionError("The shore noise was sampled for a column outside the shore window"))
+                .when(region).getShoreHeight(anyDouble(), anyDouble());
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 0D);
+
+        assertTrue(IrisComplex.aboveShoreBand(68D, region, 3D, 4D, 63D, slopes));
+        assertTrue(IrisComplex.aboveShoreBand(250D, region, 3D, 4D, 63D, slopes));
+        assertFalse(IrisComplex.aboveShoreBand(63.2D, region, 3D, 4D, 63D, slopes));
+        assertFalse(IrisComplex.aboveShoreBand(-20D, region, 3D, 4D, 63D, slopes));
+    }
+
+    @Test
+    public void equalShoreExtremesNeverSampleTheShoreNoise() {
+        IrisRegion region = mock(IrisRegion.class);
+        doReturn(2D).when(region).getShoreHeightMin();
+        doReturn(2D).when(region).getShoreHeightMax();
+        doReturn(0D).when(region).getShoreMinimumWidth();
+        doThrow(new AssertionError("Equal shore extremes need no shore noise"))
+                .when(region).getShoreHeight(anyDouble(), anyDouble());
+        ProceduralStream<Double> slopes = ProceduralStream.ofDouble((x, z) -> 0D);
+
+        assertFalse(IrisComplex.aboveShoreBand(65D, region, 3D, 4D, 63D, slopes));
+        assertTrue(IrisComplex.aboveShoreBand(65.0001D, region, 3D, 4D, 63D, slopes));
+    }
+
+    private static IrisRegion region(int variant) {
+        IrisRegion region = new IrisRegion();
+        region.setName("Shore Region " + variant);
+        region.setLandBiomeZoom(1D + variant * 0.25D);
+        KList<String> lands = new KList<>();
+        for (int index = 0; index < variant % 5; index++) {
+            lands.add("land-" + index);
+        }
+        region.setLandBiomes(lands);
+        return region;
+    }
+
+    private static IrisBiome eagerSurfaceBiome(
+            double height,
+            IrisBiome biome,
+            IrisRegion region,
+            double x,
+            double z,
+            double fluidHeight,
+            ProceduralStream<IrisBiome> landBiomes,
+            ProceduralStream<IrisBiome> seaBiomes,
+            ProceduralStream<IrisBiome> shoreBiomes,
+            ProceduralStream<Double> shoreSlopes
+    ) {
+        double shoreTop = IrisComplex.shoreBandTop(height, region, x, z, fluidHeight, shoreSlopes);
+        if (height >= fluidHeight - 1 && height <= shoreTop && !biome.isShore()) {
+            return shoreBiomes.get(x, z);
+        }
+        if (height > shoreTop && !biome.isLand()) {
+            return landBiomes.get(x, z);
+        }
+        if (height < fluidHeight && !biome.isAquatic()) {
+            return seaBiomes.get(x, z);
+        }
+        if (height == fluidHeight && !biome.isShore()) {
+            return shoreBiomes.get(x, z);
+        }
+        return biome;
+    }
+
+    private static ProceduralStream<IrisBiome> constant(IrisBiome biome) {
+        @SuppressWarnings("unchecked")
+        ProceduralStream<IrisBiome> stream = mock(ProceduralStream.class, withSettings().stubOnly());
+        doReturn(biome).when(stream).get(anyDouble(), anyDouble());
+        return stream;
+    }
+}

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexSurfaceBiomeTest.java

@@ -119,6 +119,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isAquatic();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 68D,
@@ -143,6 +145,8 @@ public class IrisComplexSurfaceBiomeTest {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(false).when(base).isShore();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 63D,
@@ -168,6 +172,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(aquatic).isShore();
         doReturn(false).when(aquatic).isLand();
         doReturn(1D).when(region).getShoreHeight(4D, 7D);
+        doReturn(0.5D).when(region).getShoreHeightMin();
+        doReturn(1.5D).when(region).getShoreHeightMax();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
                 66D,
@@ -193,6 +199,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isLand();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(0D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -218,6 +226,8 @@ public class IrisComplexSurfaceBiomeTest {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(false).when(base).isShore();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -244,6 +254,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isShore();
         doReturn(false).when(base).isLand();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         IrisBiome resolved = IrisComplex.resolveSurfaceBiome(
@@ -272,6 +284,8 @@ public class IrisComplexSurfaceBiomeTest {
         doReturn(false).when(base).isLand();
         doReturn(false).when(base).isAquatic();
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         assertSame(sea, IrisComplex.resolveSurfaceBiome(
@@ -304,6 +318,8 @@ public class IrisComplexSurfaceBiomeTest {
     public void shoreBandTopTradesHorizontalWidthForHeightOnSlopes() {
         IrisRegion region = mock(IrisRegion.class);
         doReturn(3D).when(region).getShoreHeight(12D, 18D);
+        doReturn(1D).when(region).getShoreHeightMin();
+        doReturn(5D).when(region).getShoreHeightMax();
         doReturn(3D).when(region).getShoreMinimumWidth();
 
         assertEquals(66D, IrisComplex.shoreBandTop(67D, region, 12D, 18D, 63D, constantSlope(0D)), 0D);