diff --git a/isotest/bits/material.v b/isotest/bits/material.v
index 12d49f9..dc1576f 100644
--- a/isotest/bits/material.v
+++ b/isotest/bits/material.v
@@ -19,7 +19,9 @@ mut:
 // XXX or 10% glass 90% concrete?
 // XXX do we really need such materials?
 
-struct Material {
+
+// MaterialInfo information about materials in object
+struct MaterialInfo {
 mut:
 	name string
 
@@ -27,23 +29,23 @@ mut:
 	elems map[string]&MaterialElem
 }
 
-fn new_material() &Material {
-	m := &Material{}
+fn new_material_info() &MaterialInfo {
+	mi := &MaterialInfo{}
 
-	return m
+	return mi
 }
 
 // Add elem record
-fn (mut m Material) add_elem(bits_size int, elem &Elem) {
+fn (mut mi MaterialInfo) add_elem(bits_size int, elem &Elem) {
 
 	me := &MaterialElem{bits_size, elem}
-	m.elems[elem.name] = me
+	mi.elems[elem.name] = me
 }
 
 // Get elem record by name
-fn (m &Material) get_elem_name(elem_name string) &MaterialElem {
+fn (mi &MaterialInfo) get_elem_name(elem_name string) &MaterialElem {
 	
-	me := m.elems[elem_name]
+	me := mi.elems[elem_name]
 	
 	//if isnil(me) {
 	//	panic(2)
diff --git a/isotest/bits/object.v b/isotest/bits/object.v
index 3da72c7..00c5ae9 100644
--- a/isotest/bits/object.v
+++ b/isotest/bits/object.v
@@ -21,7 +21,7 @@ mut:
 
 	// Material/Elem
 	//elem &Elem // XXX use id/enum
-	mat &Material
+	mat_info &MaterialInfo
 
 	// Position in the world
 	// XXX in map cells/coords?
@@ -44,7 +44,7 @@ mut:
 fn new_object() &Object {
 	o := &Object{
 		//elem: &Elem(0),
-		mat: &Material(0),
+		mat_info: &MaterialInfo(0),
 		//transform: new_transform(),
 	}
 	return o
@@ -66,7 +66,7 @@ fn (o &Object) mass() f32 {
 
 	mut total_mass := 0
 
-	for _, me in o.mat.elems {
+	for _, me in o.mat_info.elems {
 
 		mat_density := me.elem.density
 		mat_volume := me.bits_size