Builders all the way down

- BufferBuilderStack -> ByteBufferBuilderStack
- Create BufferBuilders on the fly, re-using backing memory
- Hard code buffer builders to triangles/block vertex format since we
  expect this to only be used for block geometry

Author: Jozufozu

common/src/lib/java/dev/engine_room/flywheel/lib/model/baked/BufferBuilderStack.java renamed to common/src/lib/java/dev/engine_room/flywheel/lib/model/baked/ByteBufferBuilderStack.java

@@ -1,31 +1,23 @@
 package dev.engine_room.flywheel.lib.model.baked;
 
-import com.mojang.blaze3d.vertex.BufferBuilder;
 import com.mojang.blaze3d.vertex.ByteBufferBuilder;
 
 import it.unimi.dsi.fastutil.objects.ReferenceArrayList;
-import net.minecraft.client.renderer.RenderType;
 
-class BufferBuilderStack {
+class ByteBufferBuilderStack {
 	private static final int INITIAL_CAPACITY_BYTES = 256 * 32;
 
 	private int nextBufferBuilderIndex = 0;
-	private final ReferenceArrayList<BufferBuilder> bufferBuilders = new ReferenceArrayList<>();
+	private final ReferenceArrayList<ByteBufferBuilder> bufferBuilders = new ReferenceArrayList<>();
 
-	private final RenderType renderType;
-
-	BufferBuilderStack(RenderType renderType) {
-		this.renderType = renderType;
-	}
-
-	BufferBuilder getOrCreateBufferBuilder() {
-		BufferBuilder bufferBuilder;
+	ByteBufferBuilder nextOrCreate() {
+		ByteBufferBuilder bufferBuilder;
 		if (nextBufferBuilderIndex < bufferBuilders.size()) {
 			bufferBuilder = bufferBuilders.get(nextBufferBuilderIndex);
 		} else {
 			// Need to allocate at least some memory up front, as BufferBuilder internally
 			// only calls `ensureCapacity` after writing a vertex.
-			bufferBuilder = new BufferBuilder(new ByteBufferBuilder(INITIAL_CAPACITY_BYTES), renderType.mode(), renderType.format());
+			bufferBuilder = new ByteBufferBuilder(INITIAL_CAPACITY_BYTES);
 			bufferBuilders.add(bufferBuilder);
 		}
 		nextBufferBuilderIndex++;

common/src/lib/java/dev/engine_room/flywheel/lib/model/baked/MeshEmitter.java

@@ -6,16 +6,18 @@
 
 import com.google.common.collect.ImmutableList;
 import com.mojang.blaze3d.vertex.BufferBuilder;
+import com.mojang.blaze3d.vertex.ByteBufferBuilder;
+import com.mojang.blaze3d.vertex.DefaultVertexFormat;
+import com.mojang.blaze3d.vertex.VertexFormat;
 
 import dev.engine_room.flywheel.api.material.Material;
 import dev.engine_room.flywheel.api.model.Mesh;
 import dev.engine_room.flywheel.api.model.Model;
-import net.minecraft.client.renderer.RenderType;
 
 class MeshEmitter {
 	private static final int INITIAL_CAPACITY = 1;
 
-	private final BufferBuilderStack bufferBuilderStack;
+	private final ByteBufferBuilderStack byteBufferBuilderStack;
 
 	private Material @UnknownNullability [] materials = new Material[INITIAL_CAPACITY];
 	private BufferBuilder @UnknownNullability [] bufferBuilders = new BufferBuilder[INITIAL_CAPACITY];
@@ -28,8 +30,8 @@ class MeshEmitter {
 
 	private int currentIndex = 0;
 
-	MeshEmitter(RenderType renderType) {
-		this.bufferBuilderStack = new BufferBuilderStack(renderType);
+	MeshEmitter(ByteBufferBuilderStack byteBufferBuilderStack) {
+		this.byteBufferBuilderStack = byteBufferBuilderStack;
 	}
 
 	public void prepare(BlockMaterialFunction blockMaterialFunction) {
@@ -84,7 +86,10 @@ public BufferBuilder getBuffer(Material material) {
 			resize(materials.length * 2);
 		}
 
-		BufferBuilder bufferBuilder = bufferBuilderStack.getOrCreateBufferBuilder();
+		ByteBufferBuilder byteBufferBuilder = byteBufferBuilderStack.nextOrCreate();
+
+		// This is only used for block models in the 5 chunk render types, so we can hard-code the mode and format.
+		BufferBuilder bufferBuilder = new BufferBuilder(byteBufferBuilder, VertexFormat.Mode.TRIANGLES, DefaultVertexFormat.BLOCK);
 
 		// currentIndex == numBufferBuildersPopulated here.
 		materials[currentIndex] = material;

common/src/lib/java/dev/engine_room/flywheel/lib/model/baked/MeshEmitterManager.java

@@ -1,6 +1,6 @@
 package dev.engine_room.flywheel.lib.model.baked;
 
-import java.util.function.Function;
+import java.util.function.BiFunction;
 
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.UnknownNullability;
@@ -19,13 +19,14 @@ class MeshEmitterManager<T extends MeshEmitter> {
 	private static final RenderType[] CHUNK_LAYERS = RenderType.chunkBufferLayers().toArray(RenderType[]::new);
 
 	private final Reference2ReferenceMap<RenderType, T> emitterMap = new Reference2ReferenceArrayMap<>();
+	private final ByteBufferBuilderStack byteBufferBuilderStack = new ByteBufferBuilderStack();
 
 	@UnknownNullability
 	private BlockMaterialFunction blockMaterialFunction;
 
-	MeshEmitterManager(Function<RenderType, T> meshEmitterFactory) {
+	MeshEmitterManager(BiFunction<ByteBufferBuilderStack, RenderType, T> meshEmitterFactory) {
 		for (RenderType renderType : CHUNK_LAYERS) {
-			emitterMap.put(renderType, meshEmitterFactory.apply(renderType));
+			emitterMap.put(renderType, meshEmitterFactory.apply(byteBufferBuilderStack, renderType));
 		}
 	}
 
@@ -35,6 +36,7 @@ public T getEmitter(RenderType renderType) {
 
 	public void prepare(BlockMaterialFunction blockMaterialFunction) {
 		this.blockMaterialFunction = blockMaterialFunction;
+		byteBufferBuilderStack.reset();
 
 		for (MeshEmitter emitter : emitterMap.values()) {
 			emitter.prepare(blockMaterialFunction);

fabric/src/lib/java/dev/engine_room/flywheel/lib/model/baked/FabricMeshEmitterManager.java

@@ -34,7 +34,7 @@ class FabricMeshEmitterManager extends MeshEmitterManager<MeshEmitter> implement
 	private BufferBuilder currentDelegate;
 
 	FabricMeshEmitterManager() {
-		super(MeshEmitter::new);
+		super((bufferBuilderStack, $) -> new MeshEmitter(bufferBuilderStack));
 	}
 
 	public BakedModel prepareForModel(BakedModel model, RenderType defaultLayer, boolean useAo, boolean defaultAo) {

neoforge/src/lib/java/dev/engine_room/flywheel/lib/model/baked/NeoforgeMeshEmitter.java

@@ -18,8 +18,8 @@ public class NeoforgeMeshEmitter extends MeshEmitter implements VertexConsumer {
 
 	private boolean defaultAo;
 
-	NeoforgeMeshEmitter(RenderType renderType) {
-		super(renderType);
+	NeoforgeMeshEmitter(ByteBufferBuilderStack byteBufferBuilderStack, RenderType renderType) {
+		super(byteBufferBuilderStack);
 		this.renderType = renderType;
 	}