Models are (actually) temporary

- Call Model#delete on instancer delete
- Add constraint to modelSupplier in Material#model
- Fix memory leak in ModelPart
- Add ArrayModelRenderer#getModel

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

@@ -19,6 +19,7 @@ public interface Material<D extends InstanceData> {
 	 *
 	 * @param key           An object that uniquely identifies the model.
 	 * @param modelSupplier A factory that creates the Model that you want to render.
+	 *                      <b>Each time {@link Supplier#get()} is called, a new Model must be created.</b>
 	 * @return An instancer for the given model, capable of rendering many copies for little cost.
 	 */
 	Instancer<D> model(Object key, Supplier<Model> modelSupplier);

src/main/java/com/jozufozu/flywheel/backend/instancing/batching/BatchedMaterial.java

@@ -42,4 +42,9 @@ public class BatchedMaterial<D extends InstanceData> implements Material<D> {
 		models.values()
 				.forEach(CPUInstancer::clear);
 	}
+
+	public void delete() {
+		models.values().forEach(CPUInstancer::delete);
+		models.clear();
+	}
 }

src/main/java/com/jozufozu/flywheel/backend/instancing/batching/BatchedMaterialGroup.java

@@ -67,6 +67,9 @@ public class BatchedMaterialGroup implements MaterialGroup {
 	}
 
 	public void delete() {
+		materials.values()
+				.forEach(BatchedMaterial::delete);
+
 		materials.clear();
 	}
 

src/main/java/com/jozufozu/flywheel/backend/instancing/batching/BatchingEngine.java

@@ -64,11 +64,13 @@ public class BatchingEngine implements Engine {
 
 	@Override
 	public void delete() {
+		for (Map<RenderType, BatchedMaterialGroup> groups : layers.values()) {
+			groups.values().forEach(BatchedMaterialGroup::delete);
+		}
 	}
 
 	@Override
 	public void beginFrame(Camera info) {
-
 	}
 
 	@Override

src/main/java/com/jozufozu/flywheel/backend/instancing/batching/CPUInstancer.java

@@ -73,4 +73,8 @@ public class CPUInstancer<D extends InstanceData> extends AbstractInstancer<D> {
 	public void notifyDirty() {
 		// noop
 	}
+
+	public void delete() {
+		modelData.delete();
+	}
 }

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

@@ -104,6 +104,8 @@ public class GPUInstancer<D extends InstanceData> extends AbstractInstancer<D> {
 
 		instanceVBO.delete();
 		vao.delete();
+
+		modelData.delete();
 	}
 
 	protected void renderSetup() {

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

@@ -43,6 +43,10 @@ public class InstancedMaterial<D extends InstanceData> implements Material<D> {
 		});
 	}
 
+	public Collection<GPUInstancer<D>> getAllInstancers() {
+		return models.values();
+	}
+
 	public int getInstanceCount() {
 		return models.values().stream().mapToInt(GPUInstancer::getInstanceCount).sum();
 	}
@@ -57,11 +61,6 @@ public class InstancedMaterial<D extends InstanceData> implements Material<D> {
 				.allMatch(GPUInstancer::isEmpty);
 	}
 
-	public void delete() {
-		models.values().forEach(GPUInstancer::delete);
-		models.clear();
-	}
-
 	/**
 	 * Clear all instance data without freeing resources.
 	 */
@@ -70,7 +69,8 @@ public class InstancedMaterial<D extends InstanceData> implements Material<D> {
 				.forEach(GPUInstancer::clear);
 	}
 
-	public Collection<GPUInstancer<D>> getAllInstancers() {
-		return models.values();
+	public void delete() {
+		models.values().forEach(GPUInstancer::delete);
+		models.clear();
 	}
 }

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

@@ -116,7 +116,6 @@ public class InstancingEngine<P extends WorldProgram> implements Engine {
 	@Override
 	public void delete() {
 		for (Map<RenderType, InstancedMaterialGroup<P>> groups : layers.values()) {
-
 			groups.values().forEach(InstancedMaterialGroup::delete);
 		}
 	}

src/main/java/com/jozufozu/flywheel/backend/model/ArrayModelRenderer.java

@@ -14,6 +14,10 @@ public class ArrayModelRenderer {
 		this.model = model;
 	}
 
+	public Model getModel() {
+		return model;
+	}
+
 	/**
 	 * Renders this model, checking first if there is anything to render.
 	 */

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

@@ -1,7 +1,10 @@
 package com.jozufozu.flywheel.core.hardcoded;
 
+import java.nio.ByteBuffer;
 import java.util.List;
 
+import org.lwjgl.system.MemoryUtil;
+
 import com.jozufozu.flywheel.api.vertex.VertexList;
 import com.jozufozu.flywheel.api.vertex.VertexType;
 import com.jozufozu.flywheel.core.Formats;
@@ -26,12 +29,14 @@ public class ModelPart implements Model {
 			this.vertices = vertices;
 		}
 
-		PosTexNormalWriterUnsafe writer = Formats.POS_TEX_NORMAL.createWriter(MemoryTracker.create(size()));
+		ByteBuffer buffer = MemoryTracker.create(size());
+		PosTexNormalWriterUnsafe writer = Formats.POS_TEX_NORMAL.createWriter(buffer);
 		for (PartBuilder.CuboidBuilder cuboid : cuboids) {
 			cuboid.buffer(writer);
 		}
 
 		reader = writer.intoReader();
+		MemoryUtil.memFree(buffer);
 	}
 
 	public static PartBuilder builder(String name, int sizeU, int sizeV) {

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

@@ -81,6 +81,6 @@ public final class WorldModelBuilder implements Bufferable {
 	}
 
 	public BlockModel intoMesh(String name) {
-		return new BlockModel(ModelUtil.getBufferBuilder(this), name);
+		return new BlockModel(this, name);
 	}
 }