MeshBatch decide if InstanceBuffer has to be reallocated of just reuploaded

Author: borisrp

h3d/impl/InstanceBuffer.hx

@@ -3,6 +3,16 @@ package h3d.impl;
 @:allow(h3d.impl.Driver)
 class InstanceBuffer {
 
+		/**
+		Bytes are structures of 5 i32 with the following values:
+		- indexCount : number of indexes per instance
+		- instanceCount : number of indexed draws
+		- startIndexLocation : offset in indexes
+		- baseVertexLocation : offset in buffer
+		- startInstanceLocation : offset in per instance buffer
+	**/
+	public static var ELEMENT_SIZE = 20;
+
 	var countBuffer : Dynamic;
 	var data : Dynamic;
 	var driver : h3d.impl.Driver;
@@ -25,38 +35,29 @@ class InstanceBuffer {
 	{
 		triCount = 0;
 		for( i in 0...commandCount ) {
-			var idxCount = bytes.getInt32(i * 20);
-			var instCount = bytes.getInt32(i * 20 + 4);
+			var idxCount = bytes.getInt32(i * ELEMENT_SIZE);
+			var instCount = bytes.getInt32(i * ELEMENT_SIZE + 4);
 			var tri = Std.int((idxCount * instCount) / 3);
 			triCount += tri;
 		}
 	}
 
-	/**
-		Bytes are structures of 5 i32 with the following values:
-		- indexCount : number of indexes per instance
-		- instanceCount : number of indexed draws
-		- startIndexLocation : offset in indexes
-		- baseVertexLocation : offset in buffer
-		- startInstanceLocation : offset in per instance buffer
-	**/
-	public function setBuffer( commandCount : Int, bytes : haxe.io.Bytes ) {
-		if(commandCount > this.commandCount){
-			dispose();
+	public function uploadBytes(commandCount : Int, bytes : haxe.io.Bytes) {
+		updateTriCount(commandCount, bytes);
+		this.commandCount = commandCount;
+		this.indexCount = 0;
+		driver = h3d.Engine.getCurrent().driver;
+		driver.uploadInstanceBufferBytes(this, 0, commandCount, bytes, 0);
+	}
 
-			updateTriCount(commandCount, bytes);
-			this.commandCount = commandCount;
-			this.indexCount = 0;
-			driver = h3d.Engine.getCurrent().driver;
-			driver.allocInstanceBuffer(this, bytes);
-		} else {
+	public function allocFromBytes(commandCount : Int, bytes : haxe.io.Bytes) {
+		dispose();
 
-			updateTriCount(commandCount, bytes);
-			this.commandCount = commandCount;
-			this.indexCount = 0;
-			driver = h3d.Engine.getCurrent().driver;
-			driver.uploadInstanceBufferBytes(this, 0, commandCount, bytes, 0);
-		}
+		updateTriCount(commandCount, bytes);
+		this.commandCount = commandCount;
+		this.indexCount = 0;
+		driver = h3d.Engine.getCurrent().driver;
+		driver.allocInstanceBuffer(this, bytes);
 	}
 
 	public function dispose() {

h3d/scene/MeshBatch.hx

@@ -281,14 +281,15 @@ class MeshBatch extends MultiMaterial {
 			primitiveSubBytes = [for ( i in 0...primitiveSubParts.length ) haxe.io.Bytes.alloc(128)];
 			instanced.commands = null;
 		}
+		var instance_size = h3d.impl.InstanceBuffer.ELEMENT_SIZE;
 		for ( i in 0...primitiveSubBytes.length ) {
-			if( primitiveSubBytes[i].length < (instanceCount+1) * 20 ) {
+			if( primitiveSubBytes[i].length < (instanceCount+1) * instance_size ) {
 				var next = haxe.io.Bytes.alloc(Std.int(primitiveSubBytes[i].length*3/2));
-				next.blit(0, primitiveSubBytes[i], 0, instanceCount * 20);
+				next.blit(0, primitiveSubBytes[i], 0, instanceCount * instance_size);
 				primitiveSubBytes[i] = next;
 			}
 		}
-		var p = instanceCount * 20;
+		var p = instanceCount * instance_size;
 		for ( mid => psBytes in primitiveSubBytes ) {
 			var primitiveSubPart = primitiveSubParts[mid];
 			var indexCount = primitiveSubPart.indexCount;
@@ -316,6 +317,7 @@ class MeshBatch extends MultiMaterial {
 		var alloc = hxd.impl.Allocator.get();
 
 		var prim = getPrimitive();
+		var instance_size = h3d.impl.InstanceBuffer.ELEMENT_SIZE;
 
 		while( p != null ) {
 			var index = 0;
@@ -355,11 +357,16 @@ class MeshBatch extends MultiMaterial {
 					if ( ibufUpload ) {
 						var psBytes = primitiveSubBytes[p.matIndex];
 						if ( start > 0 && count < instanceCount ) {
-							psBytes = psBytes.sub(start*20,count*20);
+							psBytes = psBytes.sub(start*instance_size,count*instance_size);
 							for( i in 0...count )
-								psBytes.setInt32(i*20+16, i);
+								psBytes.setInt32(i*instance_size+16, i);
+						}
+
+						if(count < ibuf.commandCount && meshBatchFlags.has(EnableResizeDown)){
+							ibuf.uploadBytes(count, psBytes);
+						} else {
+							ibuf.allocFromBytes(count, psBytes);
 						}
-						ibuf.setBuffer(count, psBytes);
 						p.instanceBuffers[index] = ibuf;
 					}
 				}