Retrieve materials and colors

[seghier]

Hello, i use this to retrieve materials and colors, sometimes i get no material and unknown type, do i miss something or this is normal?

private void ExtractMaterialData(IIfcProduct element, List<string> materialNames,
List<Color> materialColors, List<string> materialTypes, List<string> log)
{
    string materialName = "No Material";
    Color elementColor = Color.Gray;  // Changed from materialColor
    string materialType = "Unknown";

    try
    {
        // Method 1: Direct material associations
        var materialAssociations = element.HasAssociations?.OfType<IIfcRelAssociatesMaterial>();
        if (materialAssociations != null && materialAssociations.Any())
        {
            foreach (var association in materialAssociations)
            {
                var materialSelect = association.RelatingMaterial;

                if (materialSelect is IIfcMaterial material)
                {
                    materialName = !string.IsNullOrEmpty(material.Name) ? material.Name.ToString() : "Unnamed Material";
                    materialType = !string.IsNullOrEmpty(material.Category) ? material.Category.ToString() : "General";

                    // Try to get color from material
                    var matColor = GetMaterialColor(material);  // Changed variable name
                    if (matColor.HasValue)
                    {
                        elementColor = Color.FromArgb(
                            (int)(matColor.Value.R),  // Fixed property access
                            (int)(matColor.Value.G),  // Fixed property access
                            (int)(matColor.Value.B)); // Fixed property access
                    }
                }
                else if (materialSelect is IIfcMaterialLayerSetUsage layerSetUsage)
                {
                    var layerSet = layerSetUsage.ForLayerSet;
                    if (layerSet.MaterialLayers.Any())
                    {
                        var firstLayer = layerSet.MaterialLayers.First();
                        materialName = !string.IsNullOrEmpty(firstLayer.Material?.Name) ? firstLayer.Material.Name.ToString() : "Layered Material";
                        materialType = "Layered";
                    }
                }
            }
        }

        // Method 2: Check element type for materials
        if (materialName == "No Material" && element is IIfcElement ifcElement)
        {
            var elementType = ifcElement.IsTypedBy?.FirstOrDefault()?.RelatingType;
            if (elementType != null)
            {
                var typeAssociations = elementType.HasAssociations?.OfType<IIfcRelAssociatesMaterial>();
                if (typeAssociations != null && typeAssociations.Any())
                {
                    var association = typeAssociations.First();
                    if (association.RelatingMaterial is IIfcMaterial typeMaterial)
                    {
                        materialName = !string.IsNullOrEmpty(typeMaterial.Name) ? typeMaterial.Name.ToString() : "Type Material";
                        materialType = !string.IsNullOrEmpty(typeMaterial.Category) ? typeMaterial.Category.ToString() : "Type";
                    }
                }
            }
        }

        // Method 3: Try to get color from representation styles
        if (elementColor == Color.Gray)
        {
            elementColor = GetElementColor(element) ?? Color.Gray;
        }
    }
    catch (Exception ex)
    {
        log.Add($"Error extracting material for {element.GlobalId}: {ex.Message}");
    }

    materialNames.Add(materialName);
    materialColors.Add(elementColor);  // Changed from materialColor
    materialTypes.Add(materialType);
}
private Color? GetMaterialColor(IIfcMaterial material)
{
    try
    {
        // Look for material properties that might contain color information
        var properties = material.HasProperties;
        if (properties != null)
        {
            foreach (var property in properties)
            {
                if (property is IIfcMaterialProperties matProps)
                {
                    // Look for color-related properties
                    // This is simplified - actual implementation depends on your IFC file structure
                }
            }
        }
        return null;
    }
    catch
    {
        return null;
    }
}
private Color? GetElementColor(IIfcProduct element)
{
    try
    {
        if (element.Representation?.Representations != null)
        {
            foreach (var representation in element.Representation.Representations)
            {
                foreach (var item in representation.Items)
                {
                    if (item is IIfcStyledItem styledItem)
                    {
                        foreach (var style in styledItem.Styles.OfType<IIfcPresentationStyleAssignment>())
                        {
                            foreach (var styleSelect in style.Styles)
                            {
                                if (styleSelect is IIfcSurfaceStyle surfaceStyle)
                                {
                                    var renderingStyle = surfaceStyle.Styles
                                        .OfType<IIfcSurfaceStyleRendering>()
                                        .FirstOrDefault();

                                    if (renderingStyle?.SurfaceColour != null)
                                    {
                                        var ifcColor = renderingStyle.SurfaceColour;
                                        return Color.FromArgb(
                                            (int)(ifcColor.Red * 255),
                                            (int)(ifcColor.Green * 255),
                                            (int)(ifcColor.Blue * 255));
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
        return null;
    }
    catch
    {
        return null;
    }
}

[martin1cerny]

When element has multiple representation items, there might be materials assigned to these representation items as well. This would be common for elements like doors, which would have material for the panel, material for the frame, material for the door knob etc.

[andyward]

As well as the official documentation there's some good explanation of the different IFC Material approaches here

As you'll note there's a lot of ways to assign materials. You may want to look at the pattern we use in another xbim library to read Materials: https://github.com/xBimTeam/Xbim.IDS.Validator/blob/master/Xbim.IDS.Validator.Core/Extensions/IfcMaterialsExtensions.cs

[seghier]

Thank you, i will check this and try it
Grasshopper plugin almost finished but i stack in material part, and some missing geometries