Fixed GL setRenderZone (#471)

h3d/impl/GlDriver.hx

@@ -1355,8 +1355,9 @@ class GlDriver extends Driver {
 			gl.disable(GL.SCISSOR_TEST);
 		else {
 			gl.enable(GL.SCISSOR_TEST);
-			var th = curTarget == null ? bufferHeight : curTarget.height;
-			gl.scissor(x, th - (y + height), width, height);
+			if( curTarget == null )
+				y = bufferHeight - (y + height);
+			gl.scissor(x, y, width, height);
 		}
 	}