Make ContactMaterialOptions properties all optional

types/p2/index.d.ts

@@ -361,13 +361,13 @@ declare namespace p2 {
 
     export class ContactMaterialOptions {
 
-        friction: number;
-        restitution: number;
-        stiffness: number;
-        relaxation: number;
-        frictionStiffness: number;
-        frictionRelaxation: number;
-        surfaceVelocity: number;
+        friction?: number;
+        restitution?: number;
+        stiffness?: number;
+        relaxation?: number;
+        frictionStiffness?: number;
+        frictionRelaxation?: number;
+        surfaceVelocity?: number;
 
     }
 

types/p2/p2-tests.ts

@@ -4,6 +4,12 @@ var world = new p2.World({
     gravity:[0, -9.82]
 });
 
+// Set default contact material
+world.defaultContactMaterial = new p2.ContactMaterial(
+    new p2.Material(1), new p2.Material(2),
+    { friction: 1, restitution: 0 }
+)
+
 // Create an empty dynamic body
 var circleBody = new p2.Body({
     mass: 5,