Bylayer and Byblock

[Berzerker]

I've been reading up on a lot of things since my last post. I've became  a lot better at 3D and now I even understand what layout1 and layout2 are for (mostly). The difference in model space and paper space. I looked up defpoints and layer0 and pretty much get that but I'm having a problem with understanding bylayer and byblock, the difference in when to use them in a drawing and why it matters. They keep talking about "Blocks" ? you don't always make things blocks, at least I don't. I only use a block when I want a group of things to be one entity. But you don't always need everything to be one entity. then there's talking about color and how each produces a different effect/look to the object/block. I've never even used byblock on anything. When I first started I just drew everything on layer0 and changed colors as needed. Now thanks to all of you I know that's not right so I would like to understand this better as you get time to read it.

 

Thanks 

[Dana W]

First of all, you have to have good layer discipline.

 

By layer.  When you want the layer properties to control your object properties, thus avoiding having to set individual properties for every object drawn.  For instance, when I draw the outline of a counter top whether it be plan view or elevation, I always draw it on the "Counter top" layer because I have the line type, color and weight designated by the layer properties.

 

By Layer keeps all like objects the same properties.

 

I keep my object properties dropdowns on the ribbon set to By Layer all the time, and only change them to something else for new Special Case objects.

 

By Block - if your object is not a block, or part of one, there is no point.  BUT when you want certain or all objects in a block to have matching properties, make the object properties By block.  This is usually only good for dimensions.  I never use it.

Edited October 15, 2020 by Dana W

[Berzerker]

OK great now I don't feel so dumb that I've never used it. Yeah good layer discipline was not something I had till Cad64 helped me out. Thanks Cad64!

Thanks Dana W.

[Dana W]

No Prob.  I was trying to work in the word 'hole' but couldn't come up with an analogy. LOL

[Dana W]

Truthfully I don't know what By Block actually does.  It has something to do with how objects in a block behave as far as inheriting the properties of the layer it gets inserted upon.

[Berzerker]

The term he ( the guy that said it first) used way back then was "It's like cutting a hole in a piece of paper and looking through it at your drawing" 

All I could do after he left was picture myself with a big piece of paper cut in it sitting at my desk, looking at my screen on the desk.

Put a dog with one of them scratch protectors in your head and visualize  when their head looks like they pondering "What the Bleep"

 That was me.

 

[CyberAngel]

There is no reason, 9,999 times out of ten thousand, to use anything but ByLayer for color. When you use ByLayer, you can redefine the color of the layer, and that changes all the objects on that layer that have the Bylayer color. If an object's color is defined as something else, it won't change.

 

If you're doing something artistic, and you need an assortment of colors but also a way to turn groups on and off, then overriding colors might be a good idea. But that's not what AutoCAD is intended to do.

 

The ByBlock color, as you might suspect, only helps when an object is a component in a block definition. If you change the color of an instance of a block, then the ByBlock objects inside it change color, whatever layer they're on. This might be useful if only some of the components need to change. Maybe ByBlock linetypes would work in some cases.

 

If you understand basic object-oriented programming and the concept of inheritance, a ByLayer object inherits its properties from its layer, and a ByBlock object inherits its properties from its block (which can in turn inherit its properties from a layer). When you override a property, there is no inheritance.

[RobDraw]

Color and linetype overrides are used a lot more than you think, especially within blocks. Some standards use layers for object grouping and have overrides for printing purposes that deviate from the layer properties.

 

As far as what you said about what AutoCAD is intended to do, nothing could be farther from the truth. One of AutoCAD's greatest assets is how flexible it is with a vast amount of options for a wide variety of workflows.

[Berzerker]

12 hours ago, RobDraw said:

As far as what you said about what AutoCAD is intended to do, nothing could be farther from the truth.

That's why I was asking. I know different fields/occupations use AutoCad for different jobs/careers, architectural, mechanical, Auto, civil...etc.

I personally have never used ByBlock on anything and it seems I'm not alone. But I can see if you understand what it's (ByBlock) there for how it could be useful.

@CyberAngel used the term "inherits" I assume that would mean it 'Takes on" or "Is given" those properties of the layer the block is on.

 

If you were talking about the "hole" reference between @Dana W and me that was a carry over from another thread about the Layout tabs and paper space.

Edited October 17, 2020 by Berzerker

[tombu]

10 hours ago, Berzerker said:

@CyberAngel used the term "inherits" I assume that would mean it 'Takes on" or "Is given" those properties of the layer the block is on.

Actually what @CyberAngel said was If you change the color of an instance of a block, then the ByBlock objects inside it change color, whatever layer they're on.

Example:

If a block included a square assigned the color Red and a circle the color ByLayer and a triangle the color ByBlock was inserted on a layer with the color Yellow all drawn on layer 0 and then you selected the block and changed it's color to Blue the square would be Red, the circle would be Yellow (color of the Layer), and the triangle would have switched from Yellow to Blue (color you assigned the block insertion).

 

I recommend always drawing block objects on layer 0 with it's properties assigned to ByBlock.

Edited October 17, 2020 by tombu
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