Fix: Updated sdf_exporter.py based on review feedback

mahit2609 · mahit2609 · commit f8df8926db05 · 2025-01-25T20:25:59.000+05:30
Signed-off-by: mahit2609 &lt;mahitgeozujames@gmail.com&gt;
diff --git a/examples/scripts/blender/sdf_exporter.py b/examples/scripts/blender/sdf_exporter.py
@@ -1,217 +1,221 @@
+import xml.etree.ElementTree as ET
+from os import path
+from xml.dom import minidom
+
 import bpy
-import os.path
-from bpy_extras.io_utils import ImportHelper
-from bpy.props import StringProperty, BoolProperty
+from bpy.props import StringProperty
 from bpy.types import Operator
+from bpy_extras.io_utils import ImportHelper
 
-import xml.etree.ElementTree as ET
-from xml.dom import minidom
+# Tested Blender version: 4.2/4.3
 
+########################################################################################################################
+### Exports model.dae of the scene with textures, its corresponding model.sdf file, and a default model.config file ####
+########################################################################################################################
 def export_sdf(prefix_path):
-    dae_filename = 'model.dae'
-    sdf_filename = 'model.sdf'
-    model_config_filename = 'model.config'
-    lightmap_filename = 'LightmapBaked.png'
-    model_name = 'my_model'
-    meshes_folder_prefix = 'meshes/'
-    
+
+    dae_filename = "model.dae"
+    sdf_filename = "model.sdf"
+    model_config_filename = "model.config"
+    lightmap_filename = "LightmapBaked.png"
+    model_name = "my_model"
+    meshes_folder_prefix = "meshes/"
+
     # Exports the dae file and its associated textures
-    bpy.ops.wm.collada_export(filepath=prefix_path+meshes_folder_prefix+dae_filename, 
-                             check_existing=False, 
-                             filter_blender=False, 
-                             filter_image=False, 
-                             filter_movie=False, 
-                             filter_python=False, 
-                             filter_font=False, 
-                             filter_sound=False, 
-                             filter_text=False, 
-                             filter_btx=False, 
-                             filter_collada=True, 
-                             filter_folder=True, 
-                             filemode=8)
+    bpy.ops.wm.collada_export(
+        filepath=path.join(prefix_path, meshes_folder_prefix, dae_filename),
+        check_existing=False,
+        filter_blender=False,
+        filter_image=False,
+        filter_movie=False,
+        filter_python=False,
+        filter_font=False,
+        filter_sound=False,
+        filter_text=False,
+        filter_btx=False,
+        filter_collada=True,
+        filter_folder=True,
+        filemode=8,
+    )
 
+    # objects = bpy.context.selected_objects
     objects = bpy.context.selectable_objects
-    mesh_objects = [o for o in objects if o.type == 'MESH']
-    light_objects = [o for o in objects if o.type == 'LIGHT']
+    mesh_objects = [o for o in objects if o.type == "MESH"]
+    light_objects = [o for o in objects if o.type == "LIGHT"]
+
+    #############################################
+    #### export sdf xml based off the scene #####
+    #############################################
+    sdf = ET.Element("sdf", attrib={"version": "1.8"})
 
-    sdf = ET.Element('sdf', attrib={'version':'1.8'})
-    model = ET.SubElement(sdf, "model", attrib={"name":"test"})
+    # 1 model and 1 link
+    model = ET.SubElement(sdf, "model", attrib={"name": "test"})
     static = ET.SubElement(model, "static")
     static.text = "true"
-    link = ET.SubElement(model, "link", attrib={"name":"testlink"})
-
-    def get_diffuse_map(material):
-        """Helper function to safely get diffuse map from material"""
-        if not material or not material.use_nodes or not material.node_tree:
-            return ""
-        
-        nodes = material.node_tree.nodes
-        principled = next((n for n in nodes if n.type == 'BSDF_PRINCIPLED'), None)
-        
-        if not principled:
-            return ""
-            
-        base_color = principled.inputs.get('Base Color') or principled.inputs[0]
-        if not base_color.links:
-            return ""
-            
-        link_node = base_color.links[0].from_node
-        if not hasattr(link_node, 'image') or not link_node.image:
-            return ""
-            
-        return link_node.image.name
-
+    link = ET.SubElement(model, "link", attrib={"name": "testlink"})
     # for each geometry in geometry library add a <visual> tag
     for o in mesh_objects:
-        visual = ET.SubElement(link, "visual", attrib={"name":o.name})
-        
+        visual = ET.SubElement(link, "visual", attrib={"name": o.name})
+
         geometry = ET.SubElement(visual, "geometry")
         mesh = ET.SubElement(geometry, "mesh")
         uri = ET.SubElement(mesh, "uri")
-        uri.text = dae_filename
+        uri.text = path.join(meshes_folder_prefix, dae_filename)
         submesh = ET.SubElement(mesh, "submesh")
         submesh_name = ET.SubElement(submesh, "name")
         submesh_name.text = o.name
-        
-        # Material handling
+
+        # grab diffuse/albedo map
+        diffuse_map = ""
+        if o.active_material is not None:
+            nodes = o.active_material.node_tree.nodes
+            principled = next(n for n in nodes if n.type == "BSDF_PRINCIPLED")
+            if principled is not None:
+                base_color = principled.inputs["Base Color"]
+                if len(base_color.links):
+                    link_node = base_color.links[0].from_node
+                    diffuse_map = link_node.image.name
+
+        # setup diffuse/specular color
         material = ET.SubElement(visual, "material")
         diffuse = ET.SubElement(material, "diffuse")
         diffuse.text = "1.0 1.0 1.0 1.0"
         specular = ET.SubElement(material, "specular")
         specular.text = "0.0 0.0 0.0 1.0"
         pbr = ET.SubElement(material, "pbr")
         metal = ET.SubElement(pbr, "metal")
-        
-        # Get diffuse map if material exists
-        if o.active_material:
-            diffuse_map = get_diffuse_map(o.active_material)
-            if diffuse_map:
-                albedo_map = ET.SubElement(metal, "albedo_map")
-                albedo_map.text = meshes_folder_prefix + diffuse_map
-        
-        # Lightmap handling
-        if os.path.isfile(lightmap_filename):
-            light_map = ET.SubElement(metal, "light_map", attrib={"uv_set":"1"})
-            light_map.text = meshes_folder_prefix + lightmap_filename
+        if diffuse_map != "":
+            albedo_map = ET.SubElement(metal, "albedo_map")
+            albedo_map.text = path.join(meshes_folder_prefix, diffuse_map)
+
+        # for lightmapping, add the UV and turn off casting of shadows
+        if path.isfile(lightmap_filename):
+            light_map = ET.SubElement(metal, "light_map", attrib={"uv_set": "1"})
+            light_map.text = path.join(meshes_folder_prefix, lightmap_filename)
+
             cast_shadows = ET.SubElement(visual, "cast_shadows")
             cast_shadows.text = "0"
 
     def add_attenuation_tags(light_tag, blender_light):
-        """Helper function to add attenuation tags based on light type"""
         attenuation = ET.SubElement(light_tag, "attenuation")
-        
-        # Range (cutoff distance)
-        range_tag = ET.SubElement(attenuation, "range")
-        range_tag.text = str(blender_light.cutoff_distance)
-        
-        # Linear attenuation factor
+        range = ET.SubElement(attenuation, "range")
+        range.text = str(blender_light.cutoff_distance)
         linear = ET.SubElement(attenuation, "linear")
-        linear.text = "1.0"  # Default linear attenuation
-        
-        # Quadratic attenuation factor
+        linear.text = "1.0"
         quadratic = ET.SubElement(attenuation, "quadratic")
-        quadratic.text = "0.0"  # Default quadratic attenuation
-        
-        # Constant attenuation factor
+        quadratic.text = "0.0"
         constant = ET.SubElement(attenuation, "constant")
-        constant.text = "1.0"  # Default constant attenuation
+        constant.text = "1.0"
+
     
-    # Export lights
+    # export lights
     for l in light_objects:
         blender_light = l.data
-        
+
         if blender_light.type == "POINT":
-            light = ET.SubElement(link, "light", attrib={"name":l.name, "type":"point"})
+            light = ET.SubElement(link, "light", attrib={"name": l.name, "type": "point"})
             diffuse = ET.SubElement(light, "diffuse")
             diffuse.text = f"{blender_light.color.r} {blender_light.color.g} {blender_light.color.b} 1.0"
             add_attenuation_tags(light, blender_light)
-            
-        elif blender_light.type == "SPOT":
-            light = ET.SubElement(link, "light", attrib={"name":l.name, "type":"spot"})
+
+        if blender_light.type == "SPOT":
+            light = ET.SubElement(link, "light", attrib={"name": l.name, "type": "spot"})
             diffuse = ET.SubElement(light, "diffuse")
             diffuse.text = f"{blender_light.color.r} {blender_light.color.g} {blender_light.color.b} 1.0"
             add_attenuation_tags(light, blender_light)
             
-            # Add spot light specific parameters
+            # note: unsupported <spot> tags in blender
             spot = ET.SubElement(light, "spot")
             inner_angle = ET.SubElement(spot, "inner_angle")
-            inner_angle.text = str(blender_light.spot_size * 0.5)  # Convert to inner angle
+            inner_angle.text = str(blender_light.spot_size * 0.5)
             outer_angle = ET.SubElement(spot, "outer_angle")
-            outer_angle.text = str(blender_light.spot_size)  # Outer angle
+            outer_angle.text = str(blender_light.spot_size)
             falloff = ET.SubElement(spot, "falloff")
-            falloff.text = str(blender_light.spot_blend * 10)  # Approximate falloff from blend
-            
-        elif blender_light.type == "SUN":
-            light = ET.SubElement(link, "light", attrib={"name":l.name, "type":"directional"})
+            falloff.text = str(blender_light.spot_blend * 10)
+
+        if blender_light.type == "SUN":
+            light = ET.SubElement(link, "light", attrib={"name": l.name, "type": "directional"})
             diffuse = ET.SubElement(light, "diffuse")
             diffuse.text = f"{blender_light.color.r} {blender_light.color.g} {blender_light.color.b} 1.0"
-            
+
         if blender_light.type in ["SUN", "SPOT"]:
             direction = ET.SubElement(light, "direction")
             direction.text = f"{l.matrix_world[0][2]} {l.matrix_world[1][2]} {l.matrix_world[2][2]}"
 
-        # Common light properties
+        # unsupported: AREA lights
+
         cast_shadows = ET.SubElement(light, "cast_shadows")
         cast_shadows.text = "true"
-        
+
+        # todo : bpy.types.light script api lacks an intensity value, possible candidate is energy/power(Watts)?
         intensity = ET.SubElement(light, "intensity")
-        intensity.text = str(blender_light.energy)  # Use the light's energy as intensity
-    
-    # Collision tags
-    collision = ET.SubElement(link, "collision", attrib={"name":"collision"})
+        intensity.text = str(blender_light.energy)
+
+    ## sdf collision tags
+    collision = ET.SubElement(link, "collision", attrib={"name": "collision"})
+
     geometry = ET.SubElement(collision, "geometry")
     mesh = ET.SubElement(geometry, "mesh")
     uri = ET.SubElement(mesh, "uri")
-    uri.text = dae_filename
+    uri.text = path.join(meshes_folder_prefix, dae_filename)
+
     surface = ET.SubElement(collision, "surface")
-    contact = ET.SubElement(collision, "contact")
-    collide_bitmask = ET.SubElement(collision, "collide_bitmask")
+    contact = ET.SubElement(surface, "contact")
+    collide_bitmask = ET.SubElement(contact, "collide_bitmask")
     collide_bitmask.text = "0x01"
 
-    # Write SDF file
-    xml_string = ET.tostring(sdf, encoding='unicode')
+    ## sdf write to file
+    xml_string = ET.tostring(sdf, encoding="unicode")
     reparsed = minidom.parseString(xml_string)
-    with open(prefix_path+sdf_filename, "w") as sdf_file:
+    with open(path.join(prefix_path, sdf_filename), "w") as sdf_file:
         sdf_file.write(reparsed.toprettyxml(indent="  "))
 
-    # Generate model.config
-    model = ET.Element('model')
-    name = ET.SubElement(model, 'name')
+    ##############################
+    ### generate model.config ####
+    ##############################
+    model = ET.Element("model")
+    name = ET.SubElement(model, "name")
     name.text = model_name
-    version = ET.SubElement(model, 'version')
+    version = ET.SubElement(model, "version")
     version.text = "1.0"
-    sdf_tag = ET.SubElement(model, "sdf", attrib={"version":"1.8"})
+    sdf_tag = ET.SubElement(model, "sdf", attrib={"version": "1.8"})
     sdf_tag.text = sdf_filename
 
-    author = ET.SubElement(model, 'author')
-    name = ET.SubElement(author, 'name')
+    author = ET.SubElement(model, "author")
+    name = ET.SubElement(author, "name")
     name.text = "Generated by blender SDF tools"
 
-    xml_string = ET.tostring(model, encoding='unicode')
+    xml_string = ET.tostring(model, encoding="unicode")
     reparsed = minidom.parseString(xml_string)
-    with open(prefix_path+model_config_filename, "w") as config_file:
+    with open(path.join(prefix_path, model_config_filename), "w") as config_file:
         config_file.write(reparsed.toprettyxml(indent="  "))
 
+#### UI Handling ####
 class OT_TestOpenFilebrowser(Operator, ImportHelper):
     bl_idname = "test.open_filebrowser"
     bl_label = "Save"
-    
-    directory: bpy.props.StringProperty(name="Outdir Path")
-    
+
+    directory: StringProperty(name="Outdir Path")
+
     def execute(self, context):
-        if not os.path.isdir(self.directory):
-            print(self.directory + " is not a directory!")
+        """Do the export with the selected file."""
+        if not path.isdir(self.directory):
+            print(f"{self.directory} is not a directory!")
         else:
-            print("exporting to directory: " + self.directory)
+            print(f"exporting to directory: {self.directory}")
             export_sdf(self.directory)
-        return {'FINISHED'}
+        return {"FINISHED"}
 
-def register(): 
-    bpy.utils.register_class(OT_TestOpenFilebrowser) 
+def register():
+    bpy.utils.register_class(OT_TestOpenFilebrowser)
 
-def unregister(): 
+def unregister():
     bpy.utils.unregister_class(OT_TestOpenFilebrowser)
-    
+
 if __name__ == "__main__":
-    register() 
-    bpy.ops.test.open_filebrowser('INVOKE_DEFAULT')
+    register()
+    bpy.ops.test.open_filebrowser("INVOKE_DEFAULT")
+
+# alternatively comment the main code block and do a function call without going through all the ui
+# prefix_path = '/home/ddeng/blender_lightmap/final_office/office/'
+# export_sdf(prefix_path)
