Always leaving layer 0 active in SU

Dave I read you advice "One note about using layers. Always, always leave Layer 0 active. Never make other layers active. There's no need to make other layers active. When you edit components on other layers you are working on that layer anyway." and have been trying to undersand it.

When you draw in SU are you not drawing only on the Active Layer?

Does this mean that you draw an object on layer 0 the change the layer when you make it a component?

I think it would solve some visibility problems I have had that evan if I move a component to another layer the layer that was active when I first made the component must be visible to make the component visible.

The online help is not much help on this subject can you describe what is happening in layers and the basics of how you use them?

Thanks
Keith

Keith,

When you draw in SU are you not drawing only on the Active Layer? Yes. You are drawing on the active layer.

Does this mean that you draw an object on layer 0 the[n] change the layer when you make it a component? Yes. Draw an object on Layer 0 (Draw all objects on Layer 0). After you made your components, use the Entity Info box to move those components to layers as desired.

I think it would solve some visibility problems I have had that evan if I move a component to another layer the layer that was active when I first made the component must be visible to make the component visible. Unless you move the geometry inside the component to the same layer as the component, hiding the layer that was active when you drew the geometry, will hide the geometry. This is actually where the problem comes in when you start making other layers active. It is too easy to lose track of which layer you drew the geometry on. Suppose you have Layer 1 active but are editing a component on Layer 2. And suppose you later decide to turn off the components that reside on Layer 1. The geometry in the component on Layer 2 that was drawn on Layer 1 will also be turned off.

If you end up with geometry on different layers, you end up with quite a mess. The easiest way I know to fix that mess is to delete all of the layers. When you delete layers you are prompted to choose whether or not to delete the geometry on the layers or move it to the active layer.

What you really end up doing by keeping Layer 0 active and moving only components (or groups) is leaving all geometry on Layer 0. Only the components get moved to other layers. You can't turn off the active layer but it doesn't matter this way. If you turn off a layer's visibility, you also hide the geometry in that component.

There's really no point in moving the geometry to different layers since you only need to move components. If you move all the components in your model to other layers, turning off all those layers will leave you with a blank screen.

Does that make any sense?

ditto ^^

Dave what is your definition of geometry that is still on layer 0 ?

I think I better understand how it works as making sense no. I think it is just the difference between the way I think and the way the program works. If I move an component to layer 3 I see no reason that layer 0 still needs to be visible to see the component. It is apparent that somethings do not move to the new layer and this is what you call geometry.

I will sit down and try some experiments to get a better handle on what happens.

Keith

Keith, "geometry" is basically line segments and faces. That's all there is in SketchUp. If you select a component or group and change its Layer assignment in the Entity Info box, you are only moving the component but not its geometry. I know that sounds counter-intuitive but that's the way it works. To prove it to yourself, open the component like you are editing it and select some or all of the geometry inside it. You'll see that the Entity Info shows that geometry still assigned to Layer 0. You could change that if desired but it means two steps to move the geometry and the component.

Since turning off a layer hides the components on that layer, there's no reason to take the extra steps to move the geometry too. And there's no need to turn off Layer 0's visibility if the components are all moved to other layers. You can't turn off all layers anyway because the active layer can't be turned off.

As I said, you could move the geometry to another layer but it can get to be quite challenging to keep track of it that way. Suppose you edit a table leg that is on the Legs layer (which you made active) and then decide you need to edit the apron which is on the Apron layer. If you don't first stop to change active layers, the new geometry in the apron will be on the Legs layer instead. When you hide the legs to show the joinery on the aprons, you'll hide that geometry as well.

If you leave Layer 0 as active all the time, when you hide the legs, non of the apron geometry will disappear.

It may not work as you think it should--the SketchUp folks even say that SU layers are not like layers in CAD programs--but it works the way it is.

Ok I did some testing and now I understand.

Thanks Dave I feel this will clear up some problems I previously had.

(as you say I dont have to agree just undersand and use as is)

Thanks
Keith

Keith, back when I was in high school and just starting a physics class, my father who had majored in physics in college gave me a word of advice. He said there are a number of basic laws and formulae (like, Newton's laws and F=ma) that I would have to learn. Just accept them because old, dead guys proved them long ago. He also said I should save my energy for working out the stuff that isn't already proven.

Although I don't go around accepting everything, I have found that in some cases it is easier to do that than not.