add PhysX SDK and some tweaks

Prism-ScriptCore/Src/Prism/Math/Mathf.cs

@@ -0,0 +1,15 @@
+
+namespace Prism
+{
+	public static class Mathf
+	{
+		public static float Clamp(float value, float min, float max)
+		{
+			if (value < min)
+				return min;
+			if (value > max)
+				return max;
+			return value;
+		}
+	}
+}

Prism-ScriptCore/Src/Prism/Math/Vec3.cs

@@ -33,6 +33,23 @@ namespace Prism
             Z = vec.Z;
         }
 
+        public void Clamp(Vec3 min, Vec3 max)
+		{
+			X = Mathf.Clamp(X, min.X, max.X);
+			Y = Mathf.Clamp(Y, min.Y, max.Y);
+			Z = Mathf.Clamp(Z, min.Z, max.Z);
+		}
+
+		public static Vec3 operator *(Vec3 left, float scalar)
+		{
+			return new Vec3(left.X * scalar, left.Y * scalar, left.Z * scalar);
+		}
+
+		public static Vec3 operator *(float scalar, Vec3 right)
+		{
+			return new Vec3(scalar * right.X, scalar * right.Y, scalar * right.Z);
+		}
+
         public Vec2 XY {
             get { return new Vec2(X, Y); }
             set { X = value.X; Y = value.Y; }