Fix poor design choices resulting in memory leaks

- Add ShadeSeparatedBufferedData which is returned by buffering
utilities and can be released
- Remove ShadeSeparatedBufferBuilder and add ModelUtil#endAndCombine
- Add VertexList#delete
- Replace all usage of MemoryTracker with MemoryUtil
- Add FlwUtil#copyBuffer
- Turn most BlockModel constructors into static methods
- Add BakedModelBuilder#toModel

src/main/java/com/jozufozu/flywheel/api/Material.java

@@ -25,11 +25,11 @@ public interface Material<D extends InstanceData> {
 	Instancer<D> model(Object key, Supplier<Model> modelSupplier);
 
 	default Instancer<D> getModel(PartialModel partial, BlockState referenceState) {
-		return model(partial, () -> new BlockModel(partial.get(), referenceState));
+		return model(partial, () -> BlockModel.of(partial.get(), referenceState));
 	}
 
 	default Instancer<D> getModel(PartialModel partial) {
-		return model(partial, () -> new BlockModel(partial.get(), Blocks.AIR.defaultBlockState()));
+		return model(partial, () -> BlockModel.of(partial.get(), Blocks.AIR.defaultBlockState()));
 	}
 
 	default Instancer<D> getModel(PartialModel partial, BlockState referenceState, Direction dir) {
@@ -37,10 +37,10 @@ public interface Material<D extends InstanceData> {
 	}
 
 	default Instancer<D> getModel(PartialModel partial, BlockState referenceState, Direction dir, Supplier<PoseStack> modelTransform) {
-		return model(Pair.of(dir, partial), () -> new BlockModel(partial.get(), referenceState, modelTransform.get()));
+		return model(Pair.of(dir, partial), () -> BlockModel.of(partial.get(), referenceState, modelTransform.get()));
 	}
 
 	default Instancer<D> getModel(BlockState toRender) {
-		return model(toRender, () -> new BlockModel(toRender));
+		return model(toRender, () -> BlockModel.of(toRender));
 	}
 }

src/main/java/com/jozufozu/flywheel/api/vertex/VertexList.java

@@ -41,4 +41,7 @@ public interface VertexList {
 	default boolean isEmpty() {
 		return getVertexCount() == 0;
 	}
+
+	default void delete() {
+	}
 }

src/main/java/com/jozufozu/flywheel/backend/instancing/DrawBuffer.java

@@ -3,10 +3,10 @@ package com.jozufozu.flywheel.backend.instancing;
 import java.nio.ByteBuffer;
 
 import org.jetbrains.annotations.ApiStatus;
+import org.lwjgl.system.MemoryUtil;
 
 import com.jozufozu.flywheel.backend.model.BufferBuilderExtension;
 import com.jozufozu.flywheel.backend.model.DirectVertexConsumer;
-import com.mojang.blaze3d.platform.MemoryTracker;
 import com.mojang.blaze3d.vertex.VertexFormat;
 
 import net.minecraft.client.renderer.RenderType;
@@ -48,10 +48,10 @@ public class DrawBuffer {
 		int byteSize = format.getVertexSize() * (vertexCount + 1);
 
 		if (backingBuffer == null) {
-			backingBuffer = MemoryTracker.create(byteSize);
+			backingBuffer = MemoryUtil.memAlloc(byteSize);
 		}
 		if (byteSize > backingBuffer.capacity()) {
-			backingBuffer = MemoryTracker.resize(backingBuffer, byteSize);
+			backingBuffer = MemoryUtil.memRealloc(backingBuffer, byteSize);
 		}
 
 		return new DirectVertexConsumer(backingBuffer, format, vertexCount);

src/main/java/com/jozufozu/flywheel/core/hardcoded/ModelPart.java

@@ -10,7 +10,6 @@ import com.jozufozu.flywheel.api.vertex.VertexType;
 import com.jozufozu.flywheel.core.Formats;
 import com.jozufozu.flywheel.core.model.Model;
 import com.jozufozu.flywheel.core.vertex.PosTexNormalWriterUnsafe;
-import com.mojang.blaze3d.platform.MemoryTracker;
 
 public class ModelPart implements Model {
 
@@ -29,7 +28,7 @@ public class ModelPart implements Model {
 			this.vertices = vertices;
 		}
 
-		ByteBuffer buffer = MemoryTracker.create(size());
+		ByteBuffer buffer = MemoryUtil.memAlloc(size());
 		PosTexNormalWriterUnsafe writer = Formats.POS_TEX_NORMAL.createWriter(buffer);
 		for (PartBuilder.CuboidBuilder cuboid : cuboids) {
 			cuboid.buffer(writer);
@@ -65,12 +64,6 @@ public class ModelPart implements Model {
 
 	@Override
 	public void delete() {
-		if (reader instanceof AutoCloseable closeable) {
+		reader.delete();
-			try {
-				closeable.close();
-			} catch (Exception e) {
-				//
-			}
-		}
 	}
 }

src/main/java/com/jozufozu/flywheel/core/model/BakedModelBuilder.java

@@ -42,7 +42,15 @@ public final class BakedModelBuilder implements Bufferable {
 	}
 
 	@Override
-	public void bufferInto(ModelBlockRenderer blockRenderer, VertexConsumer consumer, Random random) {
+	public void bufferInto(VertexConsumer consumer, ModelBlockRenderer blockRenderer, Random random) {
 		blockRenderer.tesselateBlock(renderWorld, model, referenceState, BlockPos.ZERO, poseStack, consumer, false, random, 42, OverlayTexture.NO_OVERLAY, VirtualEmptyModelData.INSTANCE);
 	}
+
+	public BlockModel toModel(String name) {
+		return BlockModel.of(this, name);
+	}
+
+	public BlockModel toModel() {
+		return toModel(referenceState.toString());
+	}
 }

src/main/java/com/jozufozu/flywheel/core/model/BlockModel.java

@@ -1,8 +1,12 @@
 package com.jozufozu.flywheel.core.model;
 
+import java.nio.ByteBuffer;
+
 import com.jozufozu.flywheel.api.vertex.VertexList;
 import com.jozufozu.flywheel.api.vertex.VertexType;
 import com.jozufozu.flywheel.core.Formats;
+import com.mojang.blaze3d.vertex.BufferBuilder;
+import com.mojang.blaze3d.vertex.DefaultVertexFormat;
 import com.mojang.blaze3d.vertex.PoseStack;
 
 import net.minecraft.client.Minecraft;
@@ -17,28 +21,55 @@ public class BlockModel implements Model {
 	private final VertexList reader;
 	private final String name;
 
-	public BlockModel(BlockState state) {
+	public BlockModel(ByteBuffer vertexBuffer, BufferBuilder.DrawState drawState, int unshadedStartVertex, String name) {
-		this(Minecraft.getInstance()
+		if (drawState.format() != DefaultVertexFormat.BLOCK) {
+			throw new RuntimeException("Cannot use buffered data with non-block format '" + drawState.format() + "'");
+		}
+
+		reader = Formats.BLOCK.createReader(vertexBuffer, drawState.vertexCount(), unshadedStartVertex);
+
+		this.name = name;
+	}
+
+	public BlockModel(ByteBuffer vertexBuffer, BufferBuilder.DrawState drawState, String name) {
+		if (drawState.format() != DefaultVertexFormat.BLOCK) {
+			throw new RuntimeException("Cannot use buffered data with non-block format '" + drawState.format() + "'");
+		}
+
+		reader = Formats.BLOCK.createReader(vertexBuffer, drawState.vertexCount());
+
+		this.name = name;
+	}
+
+	public BlockModel(ShadeSeparatedBufferedData data, String name) {
+		this(data.vertexBuffer(), data.drawState(), data.unshadedStartVertex(), name);
+	}
+
+	public static BlockModel of(Bufferable bufferable, String name) {
+		ShadeSeparatedBufferedData data = bufferable.build();
+		BlockModel model = new BlockModel(data, name);
+		data.release();
+		return model;
+	}
+
+	public static BlockModel of(BakedModel model, BlockState referenceState) {
+		ShadeSeparatedBufferedData data = ModelUtil.getBufferedData(model, referenceState);
+		BlockModel blockModel = new BlockModel(data, referenceState.toString());
+		data.release();
+		return blockModel;
+	}
+
+	public static BlockModel of(BlockState state) {
+		return of(Minecraft.getInstance()
 				.getBlockRenderer()
 				.getBlockModel(state), state);
 	}
 
-	public BlockModel(BakedModel model, BlockState referenceState) {
+	public static BlockModel of(BakedModel model, BlockState referenceState, PoseStack ms) {
-		this(new BakedModelBuilder(model).withReferenceState(referenceState), referenceState.toString());
+		ShadeSeparatedBufferedData data = ModelUtil.getBufferedData(model, referenceState, ms);
-	}
+		BlockModel blockModel = new BlockModel(data, referenceState.toString());
-
+		data.release();
-	public BlockModel(BakedModel model, BlockState referenceState, PoseStack ms) {
+		return blockModel;
-		this(new BakedModelBuilder(model).withReferenceState(referenceState)
-				.withPoseStack(ms), referenceState.toString());
-	}
-
-	public BlockModel(Bufferable bufferable, String name) {
-		this(bufferable.build(), name);
-	}
-
-	public BlockModel(ShadeSeparatedBufferBuilder bufferBuilder, String name) {
-		this.name = name;
-		reader = Formats.BLOCK.createReader(bufferBuilder);
 	}
 
 	@Override
@@ -63,12 +94,6 @@ public class BlockModel implements Model {
 
 	@Override
 	public void delete() {
-		if (reader instanceof AutoCloseable closeable) {
+		reader.delete();
-			try {
-				closeable.close();
-			} catch (Exception e) {
-				//
-			}
-		}
 	}
 }

src/main/java/com/jozufozu/flywheel/core/model/Bufferable.java

@@ -8,12 +8,12 @@ import com.mojang.blaze3d.vertex.VertexConsumer;
 import net.minecraft.client.renderer.block.ModelBlockRenderer;
 
 /**
- * An interface for objects that can "rendered" into a BufferBuilder.
+ * An interface for objects that can buffered into a VertexConsumer.
  */
 public interface Bufferable {
-	void bufferInto(ModelBlockRenderer renderer, VertexConsumer consumer, Random random);
+	void bufferInto(VertexConsumer consumer, ModelBlockRenderer renderer, Random random);
 
-	default ShadeSeparatedBufferBuilder build() {
+	default ShadeSeparatedBufferedData build() {
-		return ModelUtil.getBufferBuilder(this);
+		return ModelUtil.getBufferedData(this);
 	}
 }

src/main/java/com/jozufozu/flywheel/core/model/ModelUtil.java

@@ -1,16 +1,20 @@
 package com.jozufozu.flywheel.core.model;
 
 import java.lang.reflect.Field;
+import java.nio.ByteBuffer;
 import java.util.Collection;
 import java.util.Random;
 import java.util.function.Supplier;
 
 import com.jozufozu.flywheel.Flywheel;
+import com.jozufozu.flywheel.backend.model.BufferBuilderExtension;
 import com.jozufozu.flywheel.util.transform.TransformStack;
 import com.mojang.blaze3d.vertex.BufferBuilder;
 import com.mojang.blaze3d.vertex.DefaultVertexFormat;
 import com.mojang.blaze3d.vertex.PoseStack;
 import com.mojang.blaze3d.vertex.VertexFormat;
+import com.mojang.blaze3d.vertex.BufferBuilder.DrawState;
+import com.mojang.datafixers.util.Pair;
 
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.renderer.RenderType;
@@ -48,39 +52,52 @@ public class ModelUtil {
 		return dispatcher;
 	}
 
-	public static ShadeSeparatedBufferBuilder getBufferBuilder(Bufferable bufferable) {
+	public static ShadeSeparatedBufferedData endAndCombine(BufferBuilder shadedBuilder, BufferBuilder unshadedBuilder) {
+		int unshadedStartVertex = ((BufferBuilderExtension) shadedBuilder).flywheel$getVertices();
+		unshadedBuilder.end();
+		Pair<DrawState, ByteBuffer> unshadedData = unshadedBuilder.popNextBuffer();
+		((BufferBuilderExtension) shadedBuilder).flywheel$appendBufferUnsafe(unshadedData.getSecond());
+		shadedBuilder.end();
+		Pair<DrawState, ByteBuffer> data = shadedBuilder.popNextBuffer();
+		return new ShadeSeparatedBufferedData.NativeImpl(data.getSecond(), data.getFirst(), unshadedStartVertex);
+	}
+
+	public static ShadeSeparatedBufferedData getBufferedData(Bufferable bufferable) {
 		ModelBlockRenderer blockRenderer = VANILLA_RENDERER.getModelRenderer();
 		ThreadLocalObjects objects = THREAD_LOCAL_OBJECTS.get();
 
 		objects.begin();
 
-		bufferable.bufferInto(blockRenderer, objects.shadeSeparatingWrapper, objects.random);
+		bufferable.bufferInto(objects.shadeSeparatingWrapper, blockRenderer, objects.random);
 
-		objects.end();
+		return objects.end();
-
-		return objects.separatedBufferBuilder;
 	}
 
-	public static ShadeSeparatedBufferBuilder getBufferBuilder(BakedModel model, BlockState referenceState, PoseStack poseStack) {
+	public static ShadeSeparatedBufferedData getBufferedData(BakedModel model, BlockState referenceState) {
+		return new BakedModelBuilder(model).withReferenceState(referenceState)
+				.build();
+	}
+
+	public static ShadeSeparatedBufferedData getBufferedData(BakedModel model, BlockState referenceState, PoseStack poseStack) {
 		return new BakedModelBuilder(model).withReferenceState(referenceState)
 				.withPoseStack(poseStack)
 				.build();
 	}
 
-	public static ShadeSeparatedBufferBuilder getBufferBuilder(BlockAndTintGetter renderWorld, BakedModel model, BlockState referenceState, PoseStack poseStack) {
+	public static ShadeSeparatedBufferedData getBufferedData(BlockAndTintGetter renderWorld, BakedModel model, BlockState referenceState, PoseStack poseStack) {
 		return new BakedModelBuilder(model).withReferenceState(referenceState)
 				.withPoseStack(poseStack)
 				.withRenderWorld(renderWorld)
 				.build();
 	}
 
-	public static ShadeSeparatedBufferBuilder getBufferBuilderFromTemplate(BlockAndTintGetter renderWorld, RenderType layer, Collection<StructureTemplate.StructureBlockInfo> blocks) {
+	public static ShadeSeparatedBufferedData getBufferedDataFromTemplate(BlockAndTintGetter renderWorld, RenderType layer, Collection<StructureTemplate.StructureBlockInfo> blocks) {
 		return new WorldModelBuilder(layer).withRenderWorld(renderWorld)
 				.withBlocks(blocks)
 				.build();
 	}
 
-	public static ShadeSeparatedBufferBuilder getBufferBuilderFromTemplate(BlockAndTintGetter renderWorld, RenderType layer, Collection<StructureTemplate.StructureBlockInfo> blocks, PoseStack poseStack) {
+	public static ShadeSeparatedBufferedData getBufferedDataFromTemplate(BlockAndTintGetter renderWorld, RenderType layer, Collection<StructureTemplate.StructureBlockInfo> blocks, PoseStack poseStack) {
 		return new WorldModelBuilder(layer).withRenderWorld(renderWorld)
 				.withBlocks(blocks)
 				.withPoseStack(poseStack)
@@ -101,20 +118,18 @@ public class ModelUtil {
 	private static class ThreadLocalObjects {
 		public final Random random = new Random();
 		public final ShadeSeparatingVertexConsumer shadeSeparatingWrapper = new ShadeSeparatingVertexConsumer();
-		public final ShadeSeparatedBufferBuilder separatedBufferBuilder = new ShadeSeparatedBufferBuilder(512);
+		public final BufferBuilder shadedBuilder = new BufferBuilder(512);
 		public final BufferBuilder unshadedBuilder = new BufferBuilder(512);
 
 		private void begin() {
-			this.separatedBufferBuilder.begin(VertexFormat.Mode.QUADS, DefaultVertexFormat.BLOCK);
+			this.shadedBuilder.begin(VertexFormat.Mode.QUADS, DefaultVertexFormat.BLOCK);
 			this.unshadedBuilder.begin(VertexFormat.Mode.QUADS, DefaultVertexFormat.BLOCK);
-			this.shadeSeparatingWrapper.prepare(this.separatedBufferBuilder, this.unshadedBuilder);
+			this.shadeSeparatingWrapper.prepare(this.shadedBuilder, this.unshadedBuilder);
 		}
 
-		private void end() {
+		private ShadeSeparatedBufferedData end() {
 			this.shadeSeparatingWrapper.clear();
-			this.unshadedBuilder.end();
+			return ModelUtil.endAndCombine(shadedBuilder, unshadedBuilder);
-			this.separatedBufferBuilder.appendUnshadedVertices(this.unshadedBuilder);
-			this.separatedBufferBuilder.end();
 		}
 	}
 }

src/main/java/com/jozufozu/flywheel/core/model/ShadeSeparatedBufferBuilder.java

@@ -1,25 +0,0 @@
-package com.jozufozu.flywheel.core.model;
-
-import java.nio.ByteBuffer;
-
-import com.jozufozu.flywheel.backend.model.BufferBuilderExtension;
-import com.mojang.blaze3d.vertex.BufferBuilder;
-import com.mojang.datafixers.util.Pair;
-
-public class ShadeSeparatedBufferBuilder extends BufferBuilder {
-	protected int unshadedStartVertex;
-
-	public ShadeSeparatedBufferBuilder(int capacity) {
-		super(capacity);
-	}
-
-	public void appendUnshadedVertices(BufferBuilder unshadedBuilder) {
-		Pair<DrawState, ByteBuffer> data = unshadedBuilder.popNextBuffer();
-		unshadedStartVertex = ((BufferBuilderExtension) this).flywheel$getVertices();
-		((BufferBuilderExtension) this).flywheel$appendBufferUnsafe(data.getSecond());
-	}
-
-	public int getUnshadedStartVertex() {
-		return unshadedStartVertex;
-	}
-}

src/main/java/com/jozufozu/flywheel/core/model/ShadeSeparatedBufferedData.java

@@ -0,0 +1,51 @@
+package com.jozufozu.flywheel.core.model;
+
+import java.nio.ByteBuffer;
+
+import org.lwjgl.system.MemoryUtil;
+
+import com.jozufozu.flywheel.util.FlwUtil;
+import com.mojang.blaze3d.vertex.BufferBuilder;
+import com.mojang.blaze3d.vertex.BufferBuilder.DrawState;
+
+public interface ShadeSeparatedBufferedData {
+	ByteBuffer vertexBuffer();
+
+	BufferBuilder.DrawState drawState();
+
+	int unshadedStartVertex();
+
+	void release();
+
+	static final class NativeImpl implements ShadeSeparatedBufferedData {
+		private final ByteBuffer vertexBuffer;
+		private final BufferBuilder.DrawState drawState;
+		private final int unshadedStartVertex;
+
+		public NativeImpl(ByteBuffer vertexBuffer, BufferBuilder.DrawState drawState, int unshadedStartVertex) {
+			this.vertexBuffer = FlwUtil.copyBuffer(vertexBuffer);
+			this.drawState = drawState;
+			this.unshadedStartVertex = unshadedStartVertex;
+		}
+
+		@Override
+		public ByteBuffer vertexBuffer() {
+			return vertexBuffer;
+		}
+
+		@Override
+		public DrawState drawState() {
+			return drawState;
+		}
+
+		@Override
+		public int unshadedStartVertex() {
+			return unshadedStartVertex;
+		}
+
+		@Override
+		public void release() {
+			MemoryUtil.memFree(vertexBuffer);
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/core/model/WorldModelBuilder.java

@@ -35,7 +35,7 @@ public final class WorldModelBuilder implements Bufferable {
 	}
 
 	@Override
-	public void bufferInto(ModelBlockRenderer modelRenderer, VertexConsumer consumer, Random random) {
+	public void bufferInto(VertexConsumer consumer, ModelBlockRenderer modelRenderer, Random random) {
 		ForgeHooksClient.setRenderType(this.layer);
 		ModelBlockRenderer.enableCaching();
 		for (StructureTemplate.StructureBlockInfo info : this.blocks) {
@@ -80,7 +80,7 @@ public final class WorldModelBuilder implements Bufferable {
 		return this;
 	}
 
-	public BlockModel intoMesh(String name) {
+	public BlockModel toModel(String name) {
-		return new BlockModel(this, name);
+		return BlockModel.of(this, name);
 	}
 }

src/main/java/com/jozufozu/flywheel/core/vertex/AbstractVertexList.java

@@ -1,39 +1,31 @@
 package com.jozufozu.flywheel.core.vertex;
 
-import java.nio.Buffer;
 import java.nio.ByteBuffer;
 
 import org.lwjgl.system.MemoryUtil;
 
 import com.jozufozu.flywheel.api.vertex.VertexList;
-import com.mojang.blaze3d.platform.MemoryTracker;
+import com.jozufozu.flywheel.util.FlwUtil;
 
-public abstract class AbstractVertexList implements VertexList, AutoCloseable {
+public abstract class AbstractVertexList implements VertexList {
 
 	protected final ByteBuffer contents;
 	protected final long base;
 	protected final int vertexCount;
 
 	protected AbstractVertexList(ByteBuffer copyFrom, int vertexCount) {
-		this.contents = MemoryTracker.create(copyFrom.capacity());
+		this.contents = FlwUtil.copyBuffer(copyFrom);
 		this.vertexCount = vertexCount;
 		this.base = MemoryUtil.memAddress(this.contents);
-		init(copyFrom);
-	}
-
-	private void init(ByteBuffer copyFrom) {
-		this.contents.order(copyFrom.order());
-		this.contents.put(copyFrom);
-		((Buffer) this.contents).flip();
-	}
-
-	@Override
-	public void close() {
-		MemoryUtil.memFree(contents);
 	}
 
 	@Override
 	public int getVertexCount() {
 		return vertexCount;
 	}
+
+	@Override
+	public void delete() {
+		MemoryUtil.memFree(contents);
+	}
 }

src/main/java/com/jozufozu/flywheel/core/vertex/BlockVertex.java

@@ -2,14 +2,9 @@ package com.jozufozu.flywheel.core.vertex;
 
 import java.nio.ByteBuffer;
 
-import com.jozufozu.flywheel.api.vertex.VertexList;
 import com.jozufozu.flywheel.api.vertex.VertexType;
 import com.jozufozu.flywheel.core.layout.BufferLayout;
 import com.jozufozu.flywheel.core.layout.CommonItems;
-import com.jozufozu.flywheel.core.model.ShadeSeparatedBufferBuilder;
-import com.mojang.blaze3d.vertex.BufferBuilder;
-import com.mojang.blaze3d.vertex.DefaultVertexFormat;
-import com.mojang.datafixers.util.Pair;
 
 public class BlockVertex implements VertexType {
 
@@ -37,6 +32,10 @@ public class BlockVertex implements VertexType {
 		return new BlockVertexListUnsafe(buffer, vertexCount);
 	}
 
+	public BlockVertexListUnsafe.Shaded createReader(ByteBuffer buffer, int vertexCount, int unshadedStartVertex) {
+		return new BlockVertexListUnsafe.Shaded(buffer, vertexCount, unshadedStartVertex);
+	}
+
 	@Override
 	public String getShaderHeader() {
 		return """
@@ -57,24 +56,4 @@ Vertex FLWCreateVertex() {
 }
 				""";
 	}
-
-	public BlockVertexListUnsafe.Shaded createReader(ByteBuffer buffer, int vertexCount, int unshadedStartVertex) {
-		return new BlockVertexListUnsafe.Shaded(buffer, vertexCount, unshadedStartVertex);
-	}
-
-	public VertexList createReader(BufferBuilder bufferBuilder) {
-		// TODO: try to avoid virtual model rendering
-		Pair<BufferBuilder.DrawState, ByteBuffer> pair = bufferBuilder.popNextBuffer();
-		BufferBuilder.DrawState drawState = pair.getFirst();
-
-		if (drawState.format() != DefaultVertexFormat.BLOCK) {
-			throw new RuntimeException("Cannot use BufferBuilder with " + drawState.format());
-		}
-
-		if (bufferBuilder instanceof ShadeSeparatedBufferBuilder separated) {
-			return createReader(pair.getSecond(), drawState.vertexCount(), separated.getUnshadedStartVertex());
-		} else {
-			return createReader(pair.getSecond(), drawState.vertexCount());
-		}
-	}
 }

src/main/java/com/jozufozu/flywheel/util/FlwUtil.java

@@ -1,9 +1,12 @@
 package com.jozufozu.flywheel.util;
 
+import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.stream.Stream;
 
+import org.lwjgl.system.MemoryUtil;
+
 import com.jozufozu.flywheel.mixin.BlockEntityRenderDispatcherAccessor;
 
 import net.minecraft.client.Minecraft;
@@ -73,4 +76,17 @@ public class FlwUtil {
 	public static <R> Stream<R> mapValues(Map<?, R> map) {
 		return map.values().stream();
 	}
+
+	/**
+	 * The returned buffer is backed by native memory and will cause a memory leak if not freed using {@link MemoryUtil#memFree(java.nio.Buffer)}.
+	 */
+	public static ByteBuffer copyBuffer(ByteBuffer buffer) {
+		int pos = buffer.position();
+		ByteBuffer copy = MemoryUtil.memAlloc(buffer.remaining());
+		copy.order(buffer.order());
+		copy.put(buffer);
+		buffer.position(pos);
+		copy.flip();
+		return copy;
+	}
 }