yang686526

dwg color question
dwg color question
hello all,
i have a question regarding an issue that i'm confused about. it has to do with the color with which entities are displayed in autocad (and in odamfcapp).
i have attached 2 dwg files which demonstrate what i'm confused about...
1) displayinblockcolor.dwg - if i open this in acad, the entities are drawn in red. they are all members of a block reference and the blockreference's properties say that its color is defined by layer, the layer's name is "lowpad--dim" and that layer's color is red.
if i explode the block reference, the circle turns black (since its color is defined by layer and it belongs to a layer which is black).
from seeing this i deduce that since 1) all the members of the block reference are drawn in red, and 2) all the exploded entities have different colors, members of a blockreference are drawn using the color of the blockreference.
2) disoplayinentitycolor.dwg - if i open this in acad, the entities are all drawn in different colors. they are all members of a block reference and the blockreference's properties say that its color is defined by layer, the layer's name is "0" and that layer's color is black.
if i explode the block reference, the entities all remain displayed in all the different colors.
from seeing this i deduce that 1) since all the entities are drawn in different colors, and 2) the blockreferences is black, members of a block reference are drawn using their own colors.
obviously i've run into a problem in logic!
what am i missing that i don't quite understand about how colors are used when dealing with blockreferences.
note that odamfcapp (dd 2.5.02) draws the entities just as autocad does, so it knows what i do not! therefore i figure someone here could me get un-confused.
thanks in advance.
pete rimkus
attached files
where are 2 special colors: byblock and bylayer.
bylayer means "use color from layer"
byblock:
if an entity resides directly in layout block (model or paper space) color with index 7 is used for it (this color is white on dark background and black on light background).
if an entity is inside a non-layout block than:
byblock means "use color from block reference entity"
layer "0" for entity inside a block means "default layer - use layer of block reference"
so if color is bylayer and layer is "0" this means "use color of block reference' layer"
the same is correct for other properties (line type, line weight etc.)
note that blocks can be nested. block reference entity may reside in some other block and it may have color byblock and layer "0".
for nested blocks the process of determining byblock values is recurcive.
or starting processing a layout you need to maintain some kind of stack of byblock values to process nested blocks.
thank you!
i will try to put some of this new knowledge to work in my autocad importer and let you know of my success.
pete