Allow material inheritance from groups or instances on default materials

[kirabo]

no link FaceBackMaterial in group?
//Function is
//static Surface^ FromSU(SUFaceRef face, bool includeMeshes, System::Collections::Generic::Dictionary<String^, Material^>^ materials)
SUMaterialRef mback = SU_INVALID;
SUFaceGetBackMaterial(face, &mback); //Error mback is 0x00
SUStringRef mbackNameRef = SU_INVALID;
SUStringCreate(&mbackNameRef);
SUMaterialGetName(mback, &mbackNameRef);

//test file is
1.zip

[kirabo]

testfile is

load error no mat info

[moethu]

I had a look at the model and it looks like your material is applied to the group instead of the surface itself. when selecting the surface both materials are set to the default material. It looks like if the default material is selected, the element can inherit the material from the group level. I'll check if I can retrieve this material setting on group level using SUDrawingElementGetMaterial

[moethu]

@kirabo I implemented a Material property on group and on instance level. This property will reflect the material you applied to the group. The surface's material properties will remain empty (or default) because that's what they are set to.

[kirabo]

bug fix
if mat is null,need check parent group mat

ADD TO Surface FromSU

if (string.IsNullOrEmpty(mbackName) && string.IsNullOrEmpty(minnerName)

URef elem;
elem = SketchUpAPI.SUGroupToDrawingElement(group);
if (elem.ptr != IntPtr.Zero)
{
SURef groupMat;
int n = SketchUpAPI.SUDrawingElementGetMaterial(elem, out groupMat);

[moethu]

Hi @kirabo I think I get your point. What you are asking for is raising a question of data integrity on my end. The job of this library is to represent the SketchUp Model as closely as possible as it is provided by the C API. Therefore I do not consider this a bug because this is how the data is returned from the C API. Inheriting materials from the group level is an interpretation done by the SketchUp Application. For example if SketchUp would from now on allow a single color only, let's say red, this libraries job would not be to override all materials with a red color. That's up to the application interpreting the data.
Your code is assuming another thing: that the default material would be null. I'd have to check that - but so far the SketchUp C API returns a material with an empty string as a name. If the material were null I should get a null pointer from the API but so far there always is a material.

I can imagine adding this feature as an optional setting when loading the model, so you are aware of the fact that this is more of an interpretation than the data stored in the model. Let me understand one thing: where are you trying to use this? In what context are you using the library? If you are using the Dynamo components I'd rather add this interpretation there.