Module Contents#

class ifcopenshell.api.material.assign_material.Usecase(file, product=None, type='IfcMaterial', material=None)#

Assigns a material to a product

When a material is assigned to a product, it means that the product is made out of that material. In its simplest form, a single material may be assigned to a product, meaning that the entire product is made out of that one material. Alternatively, a material set may be assigned to a product, meaning that the product is made out of a set of materials. There are three types of sets, including layered construction, profiled materials, and arbitrary material constituents. See ifcopenshell.api.material.add_material_set for details.

Materials are typically assigned to the element types rather than individual occurrences of elements. Individual occurrences would then inherit the material from the type.

If the type has a material set, then the geometry of the occurrences must comply with the material set. For example, if the type has a constituent set, then it is expected that all occurrences also inherit the geometry of the type, which is made out of those constituents. Alternatively, if the type has a layer set, then all occurrences must have geometry that has a thickness equal to the sum of all layers. If a type has a profile set, then all occurrences must has the same profile extruded along its axis.

For layers and profiles assigned to types, the occurrences must be assigned an IfcMaterialLayerSetUsage or an IfcMaterialProfileSetUsage. This allows individual occurrences to override the layered or profiled construction offset from a reference line.

  • product (ifcopenshell.entity_instance.entity_instance) – The IfcProduct to assign the material or material set to.

  • type (str) – Choose from “IfcMaterial”, “IfcMaterialConstituentSet”, “IfcMaterialLayerSet”, “IfcMaterialLayerSetUsage”, “IfcMaterialProfileSet”, “IfcMaterialProfileSetUsage”, or “IfcMaterialList”. Note that “Set Usages” may only be assigned to occurrences, not types.

  • material (ifcopenshell.entity_instance.entity_instance) – The IfcMaterial or material set you are assigning here.


The IfcRelAssociatesMaterial entity

Return type



# Let's start with a simple concrete material
concrete = ifcopenshell.api.run("material.add_material", model, name="CON01", category="concrete")

# Let's imagine a concrete bench made out of a single concrete
# material. Let's assign it to the type.
bench_type = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurnitureType")
ifcopenshell.api.run("material.assign_material", model,
    product=bench_type, type="IfcMaterial", material=concrete)

# Let's imagine there are a two occurrences of this bench.  It's not
# necessary to assign any material to these benches as they
# automatically inherit the material from the type.
bench1 = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurniture")
bench2 = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurniture")
ifcopenshell.api.run("type.assign_type", model, related_object=bench1, relating_type=bench_type)
ifcopenshell.api.run("type.assign_type", model, related_object=bench2, relating_type=bench_type)

# If we have a concrete wall, we should use a layer set. Again,
# let's start with a wall type, not occurrences.
wall_type = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWallType", name="WAL01")

# Even though there is only one layer in our layer set, we still use
# a layer set because it makes it clear that this is a layered
# construction. Let's say it's a 200mm thick concrete layer.
material_set = ifcopenshell.api.run("material.add_material_set", model,
    name="CON200", set_type="IfcMaterialLayerSet")
layer = ifcopenshell.api.run("material.add_layer", model, layer_set=material_set, material=steel)
ifcopenshell.api.run("material.edit_layer", model, layer=layer, attributes={"LayerThickness": 200})

# Our wall type now has the layer set assigned to it
ifcopenshell.api.run("material.assign_material", model,
    product=wall_type, type="IfcMaterialLayerSet", material=material_set)

# Let's imagine an occurrence of this wall type.
wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
ifcopenshell.api.run("type.assign_type", model, related_object=wall, relating_type=wall_type)

# Our wall occurrence needs to have a "set usage" which describes
# how the layers relate to a reference line (typically a 2D line
# representing the extents of the wall). Usages are special since
# they automatically detect the inherited material set from the
# type. You'd write similar code for a profile set.
ifcopenshell.api.run("material.assign_material", model,
    product=wall, type="IfcMaterialLayerSetUsage")

# To be complete, let's create the wall's axis and body
# representation. Notice how the axis guides the walls "reference
# line" which determines where layers are extruded from, and the
# body has a thickness of 200mm, same as our total layer set
# thickness.
axis = ifcopenshell.api.run("geometry.add_axis_representation", model,
    context=axis_context, axis=[(0.0, 0.0), (5000.0, 0.0)])
body = ifcopenshell.api.run("geometry.add_wall_representation", model,
    context=body_context, length=5000, height=3000, thickness=200)
ifcopenshell.api.run("geometry.assign_representation", model, product=wall, representation=axis)
ifcopenshell.api.run("geometry.assign_representation", model, product=wall, representation=body)
ifcopenshell.api.run("geometry.edit_object_placement", model, product=wall)
create_layer_set_usage(self, material_set)#
create_material_association(self, relating_material)#
create_profile_set_usage(self, material_set)#
get_rel_associates_material(self, material)#
update_representation_profile(self, material_set)#