Orientation of planes - handling

artmusicstudio

helllo everybody,
i have a basic question dealing with handling the plane orientation (skp6)

situation:

skp sometimes turn the orientation of the planes while constructed (well known issue, i think)

now i construct a difficult mesh / plane system, sometimes with rubies.

when i apply the same colour to the front and back face of a plane (my mistake) and have a complex construction,
it is for me impossible to see, which plane's side is front and which back

in my external vis-software i have the problem, that the skp-back-colour (for some reason or already existing colour-texture definition - by name of the colour) is shown as transparent and cannot be re-applied, so some panes are no more visible.

so the solution would be

channging the colour of the backface in skp
or
reversing the wrong-oriented faces in skp

question:

is there a way (sort of group-edit)', how to make all ' backfaces' visible, selected, or applied a colour to see, which faces are
FRONT and which BACK ?

especially applying a different colour to the backface would be nice, theni simply would reverse these faces ba hand .
can a colour-setting for backface-only be changed? i cannot find anything in the menue

sorry, maybe this is a beginner's question, but it would help me extremly

thank you and all the best for 2013 for all here!

stan

TIG

View the SKP in Monochrome mode, using a Style with a distinctive default back-color - perhaps 'bright-blue' - compared to the default front-color 'off-white'.
Then you will be able to see the orientation of the faces' fronts and backs without any applied materials getting in the way.

The direction of a face's loop determines the face's 'normal'.
A 'flat' counter-clockwise loop produces an 'up' normal, and vice versa.
This applies both in Ruby and manually made faces,
However, any face that is made 'flat', on the ground z-0, will ALWAYS faces DOWN, irrespective of its loop direction. This is to assist in a subsequent PushPull which is usually 'up' and gives the expected result it the extruded face is facing downwards...
Wrongly oriented selected faces are easily 'Reversed' using the context-menu, or in code with face.reverse! If it's a mesh with some wrongly oriented faces use Monochrome mode and View > Hidden Geometry > ON. Select one face that's correctly oriented and context-menu 'Orient' to flip all other faces to match. If there are any edges with more than two faces then the results will not be perfect because more that two faces sharing an edge cannot all be oriented the same way - topologically impossible? There is no simple API equivalent for 'face.orient', but there are some method examples around, using 'edge.reversed_in_face' etc and 'face.reverse' etc...

Most rendering apps are particularly sensitive to visible back faces, and will usually render them without materials/textures - i.e. 'blank' - either transparent, black or white.

remember that materials applied onto a group/component-instance [rather than onto the faces within it], will appear to be applied onto any default-material [both fronts and backs] although in that case the faces actually still have no material applied, but 'exploding the container' will transfer them across. Monochrome mode helps see this too...

My FixReversedFaceMaterials etc and some other similar tools [e.g. by thomthom] are designed to flip incorrectly oriented faces that have a material applied to their back only, and assumes that the back is facing the wrong way, flipping the face and the material, keeping UV-mapping of textures correct too. There are also some 'forced' options etc that might help when both sides of the face have materials and you want to flip and swap materials across too...