style.add_surface_texture to work without blender material provided

src/ifcopenshell-python/ifcopenshell/api/style/add_surface_textures.py

@@ -21,10 +21,8 @@ import ifcopenshell.api
 
 
 class Usecase:
-    def __init__(self, file, material=None, uv_maps=None):
-        """Add a surface texture based on a Blender material definition
-
-        Warning: this API can only be used with Blender data structures.
+    def __init__(self, file, material=None, uv_maps=None, textures=None):
+        """Add surface texture based on a Blender material definition or texture data.
 
         :param material: The Blender material definition with a node tree that
             is compatible with glTF. See one of the valid combinations here:
@@ -34,12 +32,26 @@ class Usecase:
             IfcTessellatedFaceSets that the representation has, obtained from
             the HasTextures attribute.
         :type uv_maps: list[ifcopenshell.entity_instance.entity_instance]
+        :param textures: A list of dictionaries containing:
+
+            1. Attributes to create IfcImageTexture.
+            2. One additional parameter `uv_mode` to map IfcImageTexture to correct
+               IfcTextureCoordinate type.
+
+            Possible `uv_mode` values:
+
+            * `UV` - use IfcTextureCoordinate from `uv_maps` parameter;
+            * `Generated` - IfcTextureCoordinateGenerator with mode COORD (autogenerated UV
+              based on geometry);
+            * `Camera` - IfcTextureCoordinateGenerator with mode COORD_EYE (autogenerated UV
+              based on camera position)
+        :type textures: list[dict]
         :return: A list of IfcImageTexture
         :rtype: list[ifcopenshell.entity_instance.entity_instance]
         """
         # TODO: This usecase currently depends on Blender's data model
         self.file = file
-        self.settings = {"material": material, "uv_maps": uv_maps or []}
+        self.settings = {"material": material, "uv_maps": uv_maps or [], "textures": textures or []}
 
     def execute(self):
         if self.file.schema == "IFC2X3":
@@ -51,6 +63,23 @@ class Usecase:
         # glTF, X3D, and IFC are compatible. As long as they have something that
         # loosely resembles the node tree, we treat it as valid.
         self.textures = []
+
+        for texture in self.settings["textures"]:
+            uv_mode = texture.get("uv_mode", None)
+            texture_data = texture.copy()
+            texture_data.pop("uv_mode", None)
+            texture = self.file.create_entity("IfcImageTexture", **texture_data)
+            if uv_mode == "Generated":
+                self.file.create_entity("IfcTextureCoordinateGenerator", Maps=[texture], Mode="COORD")
+            elif uv_mode == "Camera":
+                self.file.create_entity("IfcTextureCoordinateGenerator", Maps=[texture], Mode="COORD-EYE")
+            elif uv_mode == "UV":
+                self.apply_uv_map_to_texture(texture)
+            self.textures.append(texture)
+
+        if self.settings["material"] is None:
+            return self.textures
+
         output = {n.type: n for n in self.settings["material"].node_tree.nodes}.get("OUTPUT_MATERIAL", None)
 
         if not output:
@@ -73,6 +102,7 @@ class Usecase:
             self.detect_occlusion_map()
             self.detect_diffuse_map(bsdf)
         # We do not support Phong shading. What year is this, 1995?
+
         return self.textures
 
     def detect_unlit_emissive_map(self, bsdf):