__init__.py

            # default="*.exr;*.gif;*.hdr;*.iff;*.jpeg;*.jpg;*.pgm;*.png;*.pot;*.ppm;*.sys;*.tga;*.tiff;*.EXR;*.GIF;*.HDR;*.IFF;*.JPEG;*.JPG;*.PGM;*.PNG;*.POT;*.PPM;*.SYS;*.TGA;*.TIFF",
            # options={'HIDDEN'},
            # )

###############################################################################
# Camera POV properties.
###############################################################################
class RenderPovSettingsCamera(PropertyGroup):
    #DOF Toggle
    dof_enable: BoolProperty(
            name="Depth Of Field", description="EnablePOV-Ray Depth Of Field ",
            default=False)

    # Aperture (Intensity of the Blur)
    dof_aperture: FloatProperty(
            name="Aperture",
            description="Similar to a real camera's aperture effect over focal blur (though not "
                        "in physical units and independent of focal length). "
                        "Increase to get more blur",
            min=0.01, max=1.00, default=0.50)

    # Aperture adaptive sampling
    dof_samples_min: IntProperty(
            name="Samples Min", description="Minimum number of rays to use for each pixel",
            min=1, max=128, default=3)

    dof_samples_max: IntProperty(
            name="Samples Max", description="Maximum number of rays to use for each pixel",
            min=1, max=128, default=9)

    dof_variance: IntProperty(
            name="Variance",
            description="Minimum threshold (fractional value) for adaptive DOF sampling (up "
                        "increases quality and render time). The value for the variance should "
                        "be in the range of the smallest displayable color difference",
            min=1, max=100000, soft_max=10000, default=8192)

    dof_confidence: FloatProperty(
            name="Confidence",
            description="Probability to reach the real color value. Larger confidence values "
                        "will lead to more samples, slower traces and better images",
            min=0.01, max=0.99, default=0.20)

    normal_enable: BoolProperty(name="Perturbated Camera", default=False)
    cam_normal: FloatProperty(name="Normal Strength", min=0.0, max=1.0, default=0.0)
    normal_patterns: EnumProperty(
            name="Pattern",
            description="",
            items=(('agate', "Agate", ""), ('boxed', "Boxed", ""), ('bumps', "Bumps", ""), ('cells', "Cells", ""),
                   ('crackle', "Crackle", ""),('dents', "Dents", ""),
                   ('granite', "Granite", ""),
                   ('leopard', "Leopard", ""),
                   ('marble', "Marble", ""), ('onion', "Onion", ""), ('pavement', "Pavement", ""), ('planar', "Planar", ""),
                   ('quilted', "Quilted", ""), ('ripples', "Ripples", ""),  ('radial', "Radial", ""),
                   ('spherical', "Spherical", ""),('spiral1', "Spiral1", ""), ('spiral2', "Spiral2", ""), ('spotted', "Spotted", ""),
                   ('square', "Square", ""),('tiling', "Tiling", ""),
                   ('waves', "Waves", ""), ('wood', "Wood", ""),('wrinkles', "Wrinkles", "")),
            default='agate')
    turbulence: FloatProperty(name="Turbulence", min=0.0, max=100.0, default=0.1)
    scale: FloatProperty(name="Scale", min=0.0,default=1.0)

    ##################################CustomPOV Code############################
    # Only DUMMIES below for now:
    replacement_text: StringProperty(
            name="Texts in blend file",
            description="Type the declared name in custom POV code or an external .inc "
                        "it points at. camera {} expected",
            default="")
###############################################################################
# Light POV properties.
###############################################################################
class RenderPovSettingsLight(PropertyGroup):
    #former Space properties from  removed Blender Internal
    use_limited_texture_context: BoolProperty(
            name="",
            description="Use the limited version of texture user (for ‘old shading’ mode)",
            default=True)
    texture_context: EnumProperty(
            name="Texture context",
            description="Type of texture data to display and edit",
            items=(('MATERIAL', "", "Show material textures", "MATERIAL",0), #"Show material textures"
                   ('WORLD', "", "Show world textures", "WORLD",1), #"Show world textures"
                   ('LAMP', "", "Show lamp textures", "LIGHT",2), #"Show lamp textures"
                   ('PARTICLES', "", "Show particles textures", "PARTICLES",3), #"Show particles textures"
                   ('LINESTYLE', "", "Show linestyle textures", "LINE_DATA",4), #"Show linestyle textures"
                   ('OTHER', "", "Show other data textures", "TEXTURE_DATA",5)), #"Show other data textures"
            default = 'MATERIAL')
 
    shadow_method: EnumProperty(
                name="Shadow",
                description="",
                items=(("NOSHADOW", "No Shadow", "No Shadow"),
                       ("RAY_SHADOW", "Ray Shadow", "Ray Shadow, Use ray tracing for shadow")),
                default="RAY_SHADOW")
    active_texture_index: IntProperty(
            name = "Index for texture_slots",
            default = 0)                
###############################################################################
# World POV properties.
###############################################################################
class RenderPovSettingsWorld(PropertyGroup):
    #former Space properties from  removed Blender Internal
    use_limited_texture_context: BoolProperty(
            name="",
            description="Use the limited version of texture user (for ‘old shading’ mode)",
            default=True)
    texture_context: EnumProperty(
            name="Texture context",
            description="Type of texture data to display and edit",
            items=(('MATERIAL', "", "Show material textures", "MATERIAL",0), #"Show material textures"
                   ('WORLD', "", "Show world textures", "WORLD",1), #"Show world textures"
                   ('LAMP', "", "Show lamp textures", "LIGHT",2), #"Show lamp textures"
                   ('PARTICLES', "", "Show particles textures", "PARTICLES",3), #"Show particles textures"
                   ('LINESTYLE', "", "Show linestyle textures", "LINE_DATA",4), #"Show linestyle textures"
                   ('OTHER', "", "Show other data textures", "TEXTURE_DATA",5)), #"Show other data textures"
            default = 'MATERIAL')

    use_sky_blend: BoolProperty(
            name="Blend Sky", description="Render background with natural progression from horizon to zenith",
            default=False)
    use_sky_paper: BoolProperty(
            name="Paper Sky", description="Flatten blend or texture coordinates",
            default=False)
    use_sky_real: BoolProperty(
            name="Real Sky", description="Render background with a real horizon, relative to the camera angle",
            default=False)
            
    horizon_color: FloatVectorProperty(
            name="Horizon Color",
            description="Color at the horizon",
            precision=4, step=0.01, min=0, soft_max=1,
            default=(0.0, 0.0, 0.0), options={'ANIMATABLE'}, subtype='COLOR',
    )
    zenith_color: FloatVectorProperty(
            name="Zenith Color",
            description="Color at the zenith",
            precision=4, step=0.01, min=0, soft_max=1,
            default=(0.0, 0.0, 0.0), options={'ANIMATABLE'}, subtype='COLOR',
    )
    ambient_color: FloatVectorProperty(
            name="Ambient Color",
            description="Ambient color of the world",
            precision=4, step=0.01, min=0, soft_max=1,
            default=(0.0, 0.0, 0.0), options={'ANIMATABLE'}, subtype='COLOR',
    )
    active_texture_index: IntProperty(
            name = "Index for texture_slots",
            default = 0)
class WorldTextureSlot(PropertyGroup):
    blend_factor: FloatProperty(
                name="Blend",
                description="Amount texture affects color progression of the "
                            "background",
                soft_min=0.0, soft_max=1.0, default=1.0)

    horizon_factor: FloatProperty(
                name="Horizon",
                description="Amount texture affects color of the horizon"
                            "",
                soft_min=0.0, soft_max=1.0, default=1.0)

    object: StringProperty(
                name="Object",
                description="Object to use for mapping with Object texture coordinates",
                default="")

    texture_coords: EnumProperty(
                name="Coordinates",
                description="Texture coordinates used to map the texture onto the background",
                items=(("VIEW", "View", "Use view vector for the texture coordinates"),
                       ("GLOBAL", "Global", "Use global coordinates for the texture coordinates (interior mist)"),
                       ("ANGMAP", "AngMap", "Use 360 degree angular coordinates, e.g. for spherical light probes"),
                       ("SPHERE", "Sphere", "For 360 degree panorama sky, spherical mapped, only top half"),
                       ("EQUIRECT", "Equirectangular", "For 360 degree panorama sky, equirectangular mapping"),
                       ("TUBE", "Tube", "For 360 degree panorama sky, cylindrical mapped, only top half"),
                       ("OBJECT", "Object", "Use linked object’s coordinates for texture coordinates")),
                default="VIEW")

    use_map_blend: BoolProperty(
                name="Blend Map", description="Affect the color progression of the background",
                default=True)

    use_map_horizon: BoolProperty(
                name="Horizon Map", description="Affect the color of the horizon",
                default=False)

    use_map_zenith_down: BoolProperty(
                name="", description="Affect the color of the zenith below",
                default=False)

    use_map_zenith_up: BoolProperty(
                name="Zenith Up Map", description="Affect the color of the zenith above",
                default=False)

    zenith_down_factor: FloatProperty(
                name="Zenith Down",
                description="Amount texture affects color of the zenith below",
                soft_min=0.0, soft_max=1.0, default=1.0)

    zenith_up_factor: FloatProperty(
                name="Zenith Up",
                description="Amount texture affects color of the zenith above",
                soft_min=0.0, soft_max=1.0, default=1.0)

'''
#class WORLD_TEXTURE_SLOTS_UL_layerlist(bpy.types.UIList):
#    texture_slots:
    
class WorldTextureSlots(bpy.props.PropertyGroup):
    index = bpy.prop.PropertyInt(name='index')
    #foo  = random prop

bpy.types.World.texture_slots = bpy.props.CollectionProperty(type=PropertyGroup)

for i in range(18):  # length of world texture slots
    world.texture_slots.add()
'''


###############################################################################
# Text POV properties.
###############################################################################
class RenderPovSettingsText(PropertyGroup):
    custom_code: EnumProperty(
            name="Custom Code",
            description="rendered source: Both adds text at the "
                        "top of the exported POV-Ray file",
            items=(("3dview", "View", ""),
                   ("text", "Text", ""),
                   ("both", "Both", "")),
            default="text")

###############################################################################
# Povray Preferences.
###############################################################################
class PovrayPreferences(AddonPreferences):
    bl_idname = __name__

    branch_feature_set_povray: EnumProperty(
                name="Feature Set",
                description="Choose between official (POV-Ray) or (UberPOV) "
                            "development branch features to write in the pov file",
                items= (('povray', 'Official POV-Ray', '','PLUGIN', 0),
                        ('uberpov', 'Unofficial UberPOV', '', 'PLUGIN', 1)),
                default='povray'
                )

    filepath_povray: StringProperty(
                name="Binary Location",
                description="Path to renderer executable",
                subtype='FILE_PATH',
                )
    docpath_povray: StringProperty(
                name="Includes Location",
                description="Path to Insert Menu files",
                subtype='FILE_PATH',
                )
    def draw(self, context):
        layout = self.layout
        layout.prop(self, "branch_feature_set_povray")
        layout.prop(self, "filepath_povray")
        layout.prop(self, "docpath_povray")


classes = (
    PovrayPreferences,
    RenderPovSettingsCamera,
    RenderPovSettingsLight,    
    RenderPovSettingsWorld,
    MaterialTextureSlot,
    WorldTextureSlot,
    RenderPovSettingsMaterial,
    MaterialRaytraceTransparency,
    MaterialRaytraceMirror, 
    MaterialSubsurfaceScattering,
    RenderPovSettingsObject,
    RenderPovSettingsScene,
    RenderPovSettingsText,
    RenderPovSettingsTexture,
)


def register():

    #bpy.utils.register_module(__name__) #DEPRECATED Now imported from bpy.utils import register_class

    for cls in classes:
        register_class(cls)
 
    render.register()
    ui.register()
    primitives.register()
    nodes.register()

    '''    
        bpy.types.VIEW3D_MT_add.prepend(ui.menu_func_add)
        bpy.types.TOPBAR_MT_file_import.append(ui.menu_func_import)
        bpy.types.TEXT_MT_templates.append(ui.menu_func_templates)
        bpy.types.RENDER_PT_povray_radiosity.prepend(ui.rad_panel_func)
        bpy.types.LIGHT_PT_POV_light.prepend(ui.light_panel_func)
        bpy.types.WORLD_PT_world.prepend(ui.world_panel_func)
        # was used for parametric objects but made the other addon unreachable on
        # unregister for other tools to use created a user action call instead
        #addon_utils.enable("add_mesh_extra_objects", default_set=False, persistent=True)

        #bpy.types.TEXTURE_PT_context_texture.prepend(TEXTURE_PT_povray_type)
    '''
    bpy.types.NODE_HT_header.append(ui.menu_func_nodes)
    nodeitems_utils.register_node_categories("POVRAYNODES", node_categories)
    bpy.types.Scene.pov = PointerProperty(type=RenderPovSettingsScene)
    #bpy.types.Modifier.pov = PointerProperty(type=RenderPovSettingsModifier)
    bpy.types.Material.pov_raytrace_transparency = PointerProperty(type=MaterialRaytraceTransparency)
    bpy.types.Material.pov = PointerProperty(type=RenderPovSettingsMaterial)
    bpy.types.Material.pov_subsurface_scattering = PointerProperty(type=MaterialSubsurfaceScattering)
    bpy.types.Material.pov_raytrace_mirror = PointerProperty(type=MaterialRaytraceMirror)
    bpy.types.Texture.pov = PointerProperty(type=RenderPovSettingsTexture)
    bpy.types.Object.pov = PointerProperty(type=RenderPovSettingsObject)
    bpy.types.Camera.pov = PointerProperty(type=RenderPovSettingsCamera)
    bpy.types.Light.pov = PointerProperty(type=RenderPovSettingsLight)
    bpy.types.World.pov = PointerProperty(type=RenderPovSettingsWorld)
    bpy.types.Material.texture_slots = CollectionProperty(type = MaterialTextureSlot)
    bpy.types.World.texture_slots = CollectionProperty(type = WorldTextureSlot)
    bpy.types.Text.pov = PointerProperty(type=RenderPovSettingsText)



def unregister():
    del bpy.types.Scene.pov
    del bpy.types.Material.pov
    del bpy.types.Material.pov_subsurface_scattering
    del bpy.types.Material.pov_raytrace_mirror
    del bpy.types.Material.pov_raytrace_transparency
    #del bpy.types.Modifier.pov
    del bpy.types.Texture.pov
    del bpy.types.Object.pov
    del bpy.types.Camera.pov
    del bpy.types.Light.pov
    del bpy.types.World.pov    
    del bpy.types.Text.pov

    nodeitems_utils.unregister_node_categories("POVRAYNODES")
    bpy.types.NODE_HT_header.remove(ui.menu_func_nodes)
    '''
    #bpy.types.TEXTURE_PT_context_texture.remove(TEXTURE_PT_povray_type)
    #addon_utils.disable("add_mesh_extra_objects", default_set=False)
    bpy.types.WORLD_PT_POV_world.remove(ui.world_panel_func)
    bpy.types.LIGHT_PT_POV_light.remove(ui.light_panel_func)
    bpy.types.RENDER_PT_povray_radiosity.remove(ui.rad_panel_func)
    bpy.types.TEXT_MT_templates.remove(ui.menu_func_templates)
    bpy.types.TOPBAR_MT_file_import.remove(ui.menu_func_import)
    bpy.types.VIEW3D_MT_add.remove(ui.menu_func_add)
    '''
    #bpy.utils.unregister_module(__name__)

    nodes.unregister()
    primitives.unregister()
    ui.unregister()
    render.unregister()

    for cls in reversed(classes):
        unregister_class(cls)
 


if __name__ == "__main__":
    register()