How can I isolate one object in the viewport and still have all the lighting and models around it still affecting it?

Question

I want to isolate one object in the viewport (I know I can do that with "/"), but I want the rest of the lighting and models to still affect it.

I mainly want to use this for texturing certain elements in a big scene. Is there a way to do this or is it a bit of a reach?

Answer 1

Python script

As promised. After running the script, press Alt + Numpad / to hide/unhide. Everything except the active object, lights and meshes is hidden. Meshes other than the active object have their materials replaced with a temporary material using Alpha Blend and Alpha=0. If there's no material slot, it is created. All data is saved to a textblock, so you can hide other objects, save the file, return to it later, and unhide the objects. However, messing with material slots of "hidden" meshes, or renaming them, will hurt you.

import bpy, json

shortcut_key = "NUMPAD_SLASH"
shortcut_modifiers = {"alt": True}
save_name = "hidden"

C = bpy.context
D = bpy.data
addon_keymaps = []  # store keymaps here to access after registration

class CUSTOM_LOCAL_OT_With_Light(bpy.types.Operator):
    """Make other objects invisible, but still affect light paths
    https://blender.stackexchange.com/q/226679/60486 """
    bl_idname = "custom_local.with_light"
    bl_label = "Local view with light still affected by hidden objects"
    
    def make_invisible_material(self):
        name = "Temp.Invisible.Material"
        m = D.materials.get(name)
        if not m:
            m = D.materials.new(name)
            m.use_nodes = True
            m.blend_method = 'BLEND'
            m.node_tree.nodes['Principled BSDF'].inputs['Alpha'].default_value = 0.0
        return m
            
    def hide(self):
        engine = bpy.context.scene.render.engine
        invisible_mat = self.make_invisible_material()
        objs = []
        mats_with_fake_user = set()
        
        to_hide = (o for o in C.scene.objects
                   if o.type != 'LIGHT' and not o.hide_get() and o is not C.active_object)
        for o in to_hide: 
            entry = {"name": o.name}
            objs.append(entry)
            if o.type != 'MESH':
                o.hide_set(True)
                continue
            if o.hide_select:
                entry["was_unselectable"] = True
            else:
                o.hide_select = True
            if engine == 'CYCLES':
                if o.cycles_visibility.camera:
                    entry["camera_ray"] = True
                    o.cycles_visibility.camera = False
                continue
            entry["materials"] = []
            if not o.material_slots:  # no slot
                entry["slot_added"] = True
                bpy.ops.object.material_slot_add({'object': o})
                o.material_slots[0].material = invisible_mat
                continue
            for slot in o.material_slots:
                mat = slot.material
                slot.material = invisible_mat
                if not mat:  # empty slot
                    entry["materials"].append("")
                    continue
                if mat.use_fake_user:
                    mats_with_fake_user.add(mat.name)
                mat.use_fake_user = True
                entry["materials"].append(mat.name)
        return {"materials_with_fake_user": list(mats_with_fake_user), "objects": objs}
                
    
    def unhide(self, data):
        for entry in data["objects"]:
            o = D.objects[entry["name"]]
            o.hide_set(False)  # hidden objects were ignored, so all objects saved
                               # are objects hidden by this script
            if "was_unselectable" not in entry:
                o.hide_select = False
            if "camera_ray" in entry:
                o.cycles_visibility.camera = True
            mats = entry.get("materials")
            if mats is None:
                continue
            if "slot_added" in entry:  # remove the added slot
                bpy.ops.object.material_slot_remove({'object': o})
            for i, name in enumerate(entry["materials"]):
                mat = D.materials[name] if name else None
                o.material_slots[i].material = mat
                if mat and mat not in data["materials_with_fake_user"]:
                    mat.use_fake_user = False            
    
    def execute(self, context):
        txt = D.texts.get(save_name)
        if txt:
            self.unhide(json.loads(txt.as_string()))
            D.texts.remove(txt)
        else:
            txt = D.texts.new(save_name)
            txt.from_string(json.dumps(self.hide()))
        return {"FINISHED"}

def register():
    bpy.utils.register_class(CUSTOM_LOCAL_OT_With_Light)
    # handle the keymap
    wm = bpy.context.window_manager
    km = wm.keyconfigs.addon.keymaps.new(name='3D View Generic', space_type='VIEW_3D')
    kmi = km.keymap_items.new(CUSTOM_LOCAL_OT_With_Light.bl_idname, shortcut_key, 'PRESS', **shortcut_modifiers)
    addon_keymaps.append(km)

def unregister():
    bpy.utils.unregister_class(CUSTOM_LOCAL_OT_With_Light)
    # handle the keymap
    wm = bpy.context.window_manager
    for km in addon_keymaps:
        wm.keyconfigs.addon.keymaps.remove(km)
    # clear the list
    del addon_keymaps[:]

if __name__ == "__main__":
    register()

Answer 2

Create a new Collection.

With an object selected, press M -it moves the specific object into the collection.

Use the Isolate icon to turn OFF/ON the main Collection.

Notes:

• Shift clicking on the Isolate icon will set all nested collections
• I moved lights into a solo collection just to make it organised, but you can keep it in a main collection. Lights are not affected.
• Cycles only (so it is useless for texturing)