code: def _parse_material(effect, resolver):
      
  
      # Compute base color
      baseColorFactor = np.ones(4)
      baseColorTexture = None
      if isinstance(effect.diffuse, collada.material.Map):
          try:
              baseColorTexture = _load_texture(
                  effect.diffuse.sampler.surface.image.path, resolver)
          except BaseException:
              log.warning('unable to load base texture',
                          exc_info=True)
      elif effect.diffuse is not None:
          baseColorFactor = effect.diffuse
  
      # Compute emission color
      emissiveFactor = np.zeros(3)
      emissiveTexture = None
      if isinstance(effect.emission, collada.material.Map):
          try:
              emissiveTexture = _load_texture(
                  effect.diffuse.sampler.surface.image.path, resolver)
          except BaseException:
              log.warning('unable to load emissive texture',
                          exc_info=True)
      elif effect.emission is not None:
          emissiveFactor = effect.emission[:3]
  
      # Compute roughness
      roughnessFactor = 1.0
      if (not isinstance(effect.shininess, collada.material.Map)
              and effect.shininess is not None):
          roughnessFactor = np.sqrt(2.0 / (2.0 + effect.shininess))
  
      # Compute metallic factor
      metallicFactor = 0.0
  
      # Compute normal texture
      normalTexture = None
      if effect.bumpmap is not None:
          try:
              normalTexture = _load_texture(
                  effect.bumpmap.sampler.surface.image.path, resolver)
          except BaseException:
              log.warning('unable to load bumpmap',
                          exc_info=True)
  
      return visual.texture.PBRMaterial(
          emissiveFactor=emissiveFactor,
          emissiveTexture=emissiveTexture,
          normalTexture=normalTexture,
          baseColorTexture=baseColorTexture,
          baseColorFactor=baseColorFactor,
          metallicFactor=metallicFactor,
          roughnessFactor=roughnessFactor
      )
docs: Turn a COLLADA effect into a trimesh material.