diff --git a/h3d/impl/GlDriver.hx b/h3d/impl/GlDriver.hx
index b3b589d384..239bf0bd62 100644
--- a/h3d/impl/GlDriver.hx
+++ b/h3d/impl/GlDriver.hx
@@ -89,6 +89,7 @@ class GlDriver extends Driver {
 	static var UID = 0;
 	public var gl : GL;
 	public static var ALLOW_WEBGL2 = true;
+	public static var MAX_PRECISION = null;
 	public var textureSupport:hxd.PixelFormat;
 	#end
 
@@ -280,6 +281,9 @@ class GlDriver extends Driver {
 		var glout = new ShaderCompiler();
 		glout.glES = glES;
 		glout.version = shaderVersion;
+		#if js
+		glout.precision = MAX_PRECISION;
+		#end
 		#if !usegl
 		@:privateAccess glout.intelDriverFix = isIntelGpu;
 		#end
diff --git a/h3d/scene/Skin.hx b/h3d/scene/Skin.hx
index db9c73c0be..8f095aedf1 100644
--- a/h3d/scene/Skin.hx
+++ b/h3d/scene/Skin.hx
@@ -75,6 +75,7 @@ class Skin extends MultiMaterial {
 	var paletteChanged : Bool;
 	var skinShader : h3d.shader.SkinBase;
 	var jointsGraphics : Graphics;
+	var additivePose : Array<h3d.Matrix>;
 
 	public var showJoints : Bool;
 	public var enableRetargeting : Bool = true;
@@ -170,10 +171,14 @@ class Skin extends MultiMaterial {
 		return skinData;
 	}
 
-	public function setJointRelPosition( name : String, pos : h3d.Matrix ) {
+	public function setJointRelPosition( name : String, pos : h3d.Matrix, additive = false ) {
 		var j = skinData.namedJoints.get(name);
 		if( j == null ) return;
-		currentRelPose[j.index] = pos;
+		if( additive ) {
+			if( additivePose == null ) additivePose = [];
+			additivePose[j.index] = pos;
+		} else
+			currentRelPose[j.index] = pos;
 		jointsUpdated = true;
 	}
 
@@ -251,6 +256,10 @@ class Skin extends MultiMaterial {
 				m.multiply3x4inline(r, absPos);
 			else
 				m.multiply3x4inline(r, currentAbsPose[j.parent.index]);
+			if( additivePose != null ) {
+				var a = additivePose[id];
+				if( a != null ) m.multiply3x4inline(a, m);
+			}
 			if( bid >= 0 )
 				currentPalette[bid].multiply3x4inline(j.transPos, m);
 		}
diff --git a/hxsl/Flatten.hx b/hxsl/Flatten.hx
index 7aa1e92e4c..7fbcc9cd7a 100644
--- a/hxsl/Flatten.hx
+++ b/hxsl/Flatten.hx
@@ -184,7 +184,7 @@ class Flatten {
 				if( idx == idx2 )
 					readField(expr, pos, size);
 				else {
-					var k = 4 - pos;
+					var k = (idx2 << 2) - pos;
 					var type = switch(size) {
 					case 2: Vec2;
 					case 3: Vec3;
@@ -193,7 +193,7 @@ class Flatten {
 					}
 					{ e : TCall({ e : TGlobal(type), p : e.p, t : TVoid },[
 						readField(expr, pos, k),
-						readField(expr, pos + 1, size - k)
+						readField(expr, pos + k, size - k)
 					]), t : e.t, p : e.p }
 				}
 			case TMat4:
diff --git a/hxsl/GlslOut.hx b/hxsl/GlslOut.hx
index 5e149ef03b..e2c3463503 100644
--- a/hxsl/GlslOut.hx
+++ b/hxsl/GlslOut.hx
@@ -99,6 +99,7 @@ class GlslOut {
 	public var varNames : Map<Int,String>;
 	public var glES : Null<Float>;
 	public var version : Null<Int>;
+	public var precision : Null<String> = null;
 
 	/*
 		Intel HD driver fix:
@@ -811,6 +812,9 @@ class GlslOut {
 
 		if( isCompute ) {
 			// no prec
+		} else if( precision != null ) {
+			decl('precision $precision float;');
+			decl('precision $precision int;');
 		} else if( isVertex ) {
 			decl("precision highp float;");
 			decl("precision highp int;");
@@ -818,7 +822,7 @@ class GlslOut {
 			decl("precision mediump float;");
 			decl("precision mediump int;");
 		}
-	
+
 		initVars(s);
 
 		if( isCompute )