worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IBatchProcessor.java

@@ -62,40 +62,41 @@ public interface IBatchProcessor {
      * @return false if chunk is empty of blocks
      */
     default boolean trimY(IChunkSet set, int minY, int maxY, final boolean keepInsideRange) {
-        int minLayer = (minY - 1) >> 4;
-        int maxLayer = (maxY + 1) >> 4;
+        int minLayer = minY >> 4;
+        int maxLayer = maxY >> 4;
         if (keepInsideRange) {
-            for (int layer = set.getMinSectionPosition(); layer <= minLayer; layer++) {
-                if (set.hasSection(layer)) {
-                    if (layer == minLayer) {
-                        char[] arr = set.loadIfPresent(layer);
-                        if (arr != null) {
-                            int index = (minY & 15) << 8;
-                            for (int i = 0; i < index; i++) {
-                                arr[i] = BlockTypesCache.ReservedIDs.__RESERVED__;
-                            }
-                            set.setBlocks(layer, arr);
-                        }
-                    } else {
-                        set.setBlocks(layer, null);
+            for (int layer = set.getMinSectionPosition(); layer <= set.getMaxSectionPosition(); layer++) {
+                if (!set.hasSection(layer)) {
+                    continue;
+                }
+                // wipe all data from chunk layers above or below the max / min layer
+                if (layer < minLayer || layer > maxLayer) {
+                    set.setBlocks(layer, null);
+                    continue;
+                }
+                // if chunk layer / section is fully enclosed by minY to maxY, keep as is
+                if (layer > minLayer && layer < maxLayer) {
+                    continue;
+                }
+                char[] blocks = set.loadIfPresent(layer);
+                if (blocks == null) {
+                    continue;
+                }
+                // When on the minimum layer (as defined by minY), remove blocks up to minY (exclusive)
+                if (layer == minLayer) {
+                    int index = (minY & 15) << 8;
+                    for (int i = 0; i < index; i++) {
+                        blocks[i] = BlockTypesCache.ReservedIDs.__RESERVED__;
                     }
                 }
-            }
-            for (int layer = maxLayer; layer <= set.getMaxSectionPosition(); layer++) {
-                if (set.hasSection(layer)) {
-                    if (layer == maxLayer) {
-                        char[] arr = set.loadIfPresent(layer);
-                        if (arr != null) {
-                            int index = ((maxY + 1) & 15) << 8;
-                            for (int i = index; i < arr.length; i++) {
-                                arr[i] = BlockTypesCache.ReservedIDs.__RESERVED__;
-                            }
-                            set.setBlocks(layer, arr);
-                        }
-                    } else {
-                        set.setBlocks(layer, null);
+                // When on the maximum layer (as defined by maxY), remove blocks above maxY (exclusive)
+                if (layer == maxLayer) {
+                    int index = ((maxY & 15) + 1) << 8;
+                    for (int i = index; i < blocks.length; i++) {
+                        blocks[i] = BlockTypesCache.ReservedIDs.__RESERVED__;
                     }
                 }
+                set.setBlocks(layer, blocks);
             }
             try {
                 int layer = (minY - 15) >> 4;

worldedit-core/src/test/java/com/fastasyncworldedit/core/queue/IBatchProcessorTest.java

@@ -0,0 +1,136 @@
+package com.fastasyncworldedit.core.queue;
+
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import org.jetbrains.annotations.Nullable;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.parallel.Isolated;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+class IBatchProcessorTest {
+
+    @Nested
+    @Isolated
+    class trimY {
+
+        private static final char[] CHUNK_DATA = new char[16 * 16 * 16];
+        private static final char[] SLICE_AIR = new char[16 * 16];
+        private static final char[] SLICE_RESERVED = new char[16 * 16];
+        private final IBatchProcessor processor = new NoopBatchProcessor();
+
+        static {
+            Arrays.fill(CHUNK_DATA, (char) BlockTypesCache.ReservedIDs.AIR);
+            Arrays.fill(SLICE_AIR, (char) BlockTypesCache.ReservedIDs.AIR);
+            Arrays.fill(SLICE_RESERVED, (char) BlockTypesCache.ReservedIDs.__RESERVED__);
+        }
+
+        @ParameterizedTest
+        @MethodSource("provideTrimYInBoundsParameters")
+        void testFullChunkSelectedInBoundedRegion(int minY, int maxY, int minSection, int maxSection) {
+            final IChunkSet set = mock();
+
+            char[][] sections = new char[(320 + 64) >> 4][CHUNK_DATA.length];
+            for (final char[] chars : sections) {
+                System.arraycopy(CHUNK_DATA, 0, chars, 0, CHUNK_DATA.length);
+            }
+
+            when(set.getMinSectionPosition()).thenReturn(-64 >> 4);
+            when(set.getMaxSectionPosition()).thenReturn(319 >> 4);
+            when(set.hasSection(anyInt())).thenReturn(true);
+            when(set.loadIfPresent(anyInt())).thenAnswer(invocationOnMock -> sections[invocationOnMock.<Integer>getArgument(0) + 4]);
+            doAnswer(invocationOnMock -> {
+                sections[invocationOnMock.<Integer>getArgument(0) + 4] = invocationOnMock.getArgument(1);
+                return null;
+            }).when(set).setBlocks(anyInt(), any());
+
+            processor.trimY(set, minY, maxY, true);
+
+
+            for (int section = -64 >> 4; section < 320 >> 4; section++) {
+                int sectionIndex = section + 4;
+                char[] palette = sections[sectionIndex];
+                if (section < minSection) {
+                    assertNull(palette, "expected section below minimum section to be null");
+                    continue;
+                }
+                if (section > maxSection) {
+                    assertNull(palette, "expected section above maximum section to be null");
+                    continue;
+                }
+                if (section == minSection) {
+                    for (int slice = 0; slice < 16; slice++) {
+                        boolean shouldContainBlocks = slice >= (minY % 16);
+                        // If boundaries only span one section, the upper constraints have to be checked explicitly
+                        if (section == maxSection) {
+                            shouldContainBlocks &= slice <= (maxY % 16);
+                        }
+                        assertArrayEquals(
+                                shouldContainBlocks ? SLICE_AIR : SLICE_RESERVED,
+                                Arrays.copyOfRange(palette, slice << 8, (slice + 1) << 8),
+                                ("[lower] slice %d (y=%d) expected to contain " + (shouldContainBlocks ? "air" : "nothing"))
+                                        .formatted(slice, ((section << 4) + slice))
+                        );
+                    }
+                    continue;
+                }
+                if (section == maxSection) {
+                    for (int slice = 0; slice < 16; slice++) {
+                        boolean shouldContainBlocks = slice <= (maxY % 16);
+                        assertArrayEquals(
+                                shouldContainBlocks ? SLICE_AIR : SLICE_RESERVED,
+                                Arrays.copyOfRange(palette, slice << 8, (slice + 1) << 8),
+                                ("[upper] slice %d (y=%d) expected to contain " + (shouldContainBlocks ? "air" : "nothing"))
+                                        .formatted(slice, ((section << 4) + slice))
+                        );
+                    }
+                    continue;
+                }
+                assertArrayEquals(CHUNK_DATA, palette, "full captured chunk @ %d should contain full data".formatted(section));
+            }
+
+        }
+
+        /**
+         * Arguments explained:
+         * 1. minimum y coordinate (inclusive)
+         * 2. maximum y coordinate (inclusive)
+         * 3. chunk section which contains minimum y coordinate
+         * 4. chunk section which contains maximum y coordinate
+         */
+        private static Stream<Arguments> provideTrimYInBoundsParameters() {
+            return Stream.of(
+                    Arguments.of(64, 72, 4, 4),
+                    Arguments.of(-64, 0, -4, 0),
+                    Arguments.of(0, 128, 0, 8),
+                    Arguments.of(16, 132, 1, 8),
+                    Arguments.of(4, 144, 0, 9),
+                    Arguments.of(12, 255, 0, 15),
+                    Arguments.of(24, 103, 1, 6)
+            );
+        }
+
+    }
+
+    private static final class NoopBatchProcessor implements IBatchProcessor {
+
+        @Override
+        public IChunkSet processSet(final IChunk chunk, final IChunkGet get, final IChunkSet set) {
+            return set;
+        }
+
+        @Override
+        public @Nullable Extent construct(final Extent child) {
+            return null;
+        }
+
+    }
+
+}