[abenedik]

MultiMaterialBox is more complicated 3D objects because it is actually a Model3DGroup with 6 difference GeometryModel3D - one for each material.

Below I am posting the code to create MultiMaterialBox (taken from Ab3d.Models.Model3DFactory).

You should change the code so that you will create 6 PlaneMesh3D objects to create MeshGeometryes - as with the previous sample on this post you need to create them with size = 1 and at (0, 0, 0). Than freeze the meshes.

After that you should create GeometryModel3D-s with different materials, group them into Model3DGroup and apply transformation to Model3DGroup to scale and position the group.

I would also advice you that you use only one instance of Material for the same material (this means that you should use as little Material instances as possible - so all Orange materials should be in one Material instace). You can also freeze the material (you should freeze as many things as possible).

This will surely increase performance a lot, but I am not sure if the performance for 5000 MultiMaterialBox will be really good.

Code:

/// <summary>
        /// Creates a 3D Box model where each side can have its own material.
        /// </summary>
        /// <remarks>
        /// <para>
        /// The <b>CreateMultiMaterialBox</b> creates a 3D box where each side of the box can have its own material.
        /// </para>
        /// <para>
        /// To create a 3D box where all sides have the same material use <see cref="CreateBox(Point3D, Size3D, int, int, int, Material)"/> method.
        /// </para>
        /// </remarks>        
        /// <param name="centerPosition">box center position</param>
        /// <param name="size">size of the box</param>
        /// <param name="xCellsCount">number of cells in x direction</param>
        /// <param name="yCellsCount">number of cells in y direction</param>
        /// <param name="zCellsCount">number of cells in z direction</param>
        /// <param name="topMaterial">top material</param>
        /// <param name="bottomMaterial">bottom material</param>
        /// <param name="leftMaterial">left material</param>
        /// <param name="rightMaterial">right material</param>
        /// <param name="frontMaterial">front material</param>
        /// <param name="backMaterial">back material</param>
        /// <param name="isBackMaterialSet">is true the BackMaterial for each side is set to the same value as Material.</param>
        /// <returns>3D Box model as Model3DGroup</returns>
        public static Model3DGroup CreateMultiMaterialBox(Point3D centerPosition, Size3D size,
                                                          int xCellsCount, int yCellsCount, int zCellsCount,
                                                          Material topMaterial, Material bottomMaterial,
                                                          Material leftMaterial, Material rightMaterial,
                                                          Material frontMaterial, Material backMaterial,
                                                          bool isBackMaterialSet)
        {
            Size3D halfSize;
            Model3DGroup boxGroup;
            PlaneMesh3D onePlaneMesh;
            GeometryModel3D oneGeometryModel3D;

            halfSize = new Size3D(size.X / 2, size.Y / 2, size.Z / 2);

            boxGroup = new Model3DGroup();

            // Top side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X, centerPosition.Y + halfSize.Y, centerPosition.Z),
                                           new Vector3D(0, 1, 0), // normal: up
                                           new Vector3D(0, 0, -1), // heightDirection: into the screen
                                           new Size(size.X, size.Z),
                                           xCellsCount, zCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = topMaterial;

            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = topMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);


            // Bottom side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X, centerPosition.Y - halfSize.Y, centerPosition.Z),
                                           new Vector3D(0, -1, 0), // normal: down
                                           new Vector3D(0, 0, -1), // heightDirection: into the screen
                                           new Size(size.X, size.Z),
                                           xCellsCount, zCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = bottomMaterial;

            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = bottomMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);


            // Left side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X - halfSize.X, centerPosition.Y, centerPosition.Z),
                                           new Vector3D(-1, 0, 0), // normal: to the left
                                           new Vector3D(0, 1, 0), // heightDirection: up
                                           new Size(size.Z, size.Y),
                                           zCellsCount, yCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = leftMaterial;
            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = leftMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);


            // Right side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X + halfSize.X, centerPosition.Y, centerPosition.Z),
                                           new Vector3D(1, 0, 0), // normal: to the right
                                           new Vector3D(0, 1, 0), // heightDirection: up
                                           new Size(size.Z, size.Y),
                                           zCellsCount, yCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = rightMaterial;
            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = rightMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);


            // Front side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X, centerPosition.Y, centerPosition.Z + halfSize.Z),
                                           new Vector3D(0, 0, 1), // normal: away from screen
                                           new Vector3D(0, 1, 0), // heightDirection: up
                                           new Size(size.X, size.Y),
                                           xCellsCount, yCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = frontMaterial;
            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = frontMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);


            // Back side
            onePlaneMesh = new PlaneMesh3D(new Point3D(centerPosition.X, centerPosition.Y, centerPosition.Z - halfSize.Z),
                                           new Vector3D(0, 0, -1), // normal: away from screen
                                           new Vector3D(0, 1, 0), // heightDirection: up
                                           new Size(size.X, size.Y),
                                           xCellsCount, yCellsCount);

            oneGeometryModel3D = new GeometryModel3D();
            oneGeometryModel3D.Geometry = onePlaneMesh.Geometry;
            oneGeometryModel3D.Material = backMaterial;
            if (isBackMaterialSet)
                oneGeometryModel3D.BackMaterial = backMaterial;

            boxGroup.Children.Add(oneGeometryModel3D);

            return boxGroup;
        }