Hey @LorenzJaeger,

I hope you have not spent too much time on this, but there is an easy fix to this problem. You must send the core message COREMSG_CINEMA_FORCE_AM_UPDATE, i.e., in the context of your code:

int index_base = 0; { index_base = SIMPLEMATERIAL_PARENT_GROUP_DYNAMIC; target_material->SetParameter(index_base + 2, material_to_add, DESCFLAGS_SET::NONE); EventAdd(); SpecialEventAdd(COREMSG_CINEMA_FORCE_AM_UPDATE); }

I am not sure if we will consider this a bug or an intended limitation, because the lack of an GUI refresh when setting a link parameter might be tied to the threading limitations of the message system. I will keep this thread updated.

Cheers,
Ferdinand

The result:
material.gif

The full method in the context of your code:

Bool SimpleMaterial::Message(GeListNode* node, Int32 type, void* data) { if (type == MSG_UPDATE) updatecount++; switch (type) { case MATPREVIEW_GET_OBJECT_INFO: { MatPreviewObjectInfo* info = (MatPreviewObjectInfo*)data; info->bHandlePreview = true; // own preview handling info->bNeedsOwnScene = true; // we need our own entry in the preview scene cache info->bNoStandardScene = false; // we modify the standard scene info->lFlags = 0; return true; break; } case MATPREVIEW_MODIFY_CACHE_SCENE: // modify the preview scene here. We have a pointer to a scene inside the preview scene cache. // our scene contains the object { MatPreviewModifyCacheScene* scene = (MatPreviewModifyCacheScene*)data; // get the striped plane from the preview BaseObject* plane = scene->pDoc->SearchObject(String("Polygon")); if (plane) plane->SetRelScale(Vector(0.1)); // scale it a bit return true; break; } case MATPREVIEW_PREPARE_SCENE: // let the preview handle the rest... return true; break; case MATPREVIEW_GENERATE_IMAGE: { MatPreviewGenerateImage* image = (MatPreviewGenerateImage*)data; if (image->pDoc) { Int32 w = image->pDest->GetBw(); Int32 h = image->pDest->GetBh(); BaseContainer bcRender = image->pDoc->GetActiveRenderData()->GetData(); bcRender.SetFloat(RDATA_XRES, w); bcRender.SetFloat(RDATA_YRES, h); bcRender.SetInt32(RDATA_ANTIALIASING, ANTI_GEOMETRY); if (image->bLowQuality) bcRender.SetInt32(RDATA_RENDERENGINE, RDATA_RENDERENGINE_PREVIEWHARDWARE); image->pDest->Clear(0, 0, 0); // image->lResult = RenderDocument(image->pDoc, bcRender, nullptr, nullptr, image->pDest, // RENDERFLAGS::EXTERNAL | RENDERFLAGS::PREVIEWRENDER, image->pThread); } return true; break; } case MSG_DESCRIPTION_COMMAND: { BaseMaterial* mat = reinterpret_cast<BaseMaterial*>(node); if (mat == nullptr) return false; auto doc = mat->GetDocument(); if (doc == nullptr) return false; auto target_material = static_cast<BaseMaterial*>(node); if (target_material == nullptr) return false; if (GeIsMainThread()) { auto* material_to_add = BaseMaterial::Alloc(ID_SIMPLEMAT); if (!material_to_add) return false; doc->StartUndo(); doc->InsertMaterial(material_to_add); EventAdd(); doc->AddUndo(UNDOTYPE::NEWOBJ, material_to_add); doc->EndUndo(); int index_base = 0; { index_base = SIMPLEMATERIAL_PARENT_GROUP_DYNAMIC; target_material->SetParameter(index_base + 2, material_to_add, DESCFLAGS_SET::NONE); EventAdd(); SpecialEventAdd(COREMSG_CINEMA_FORCE_AM_UPDATE); } } break; } case MATPREVIEW_GET_PREVIEW_ID: { *((Int32*)data) = SIMPLEMATERIAL_MAT_PREVIEW; return true; break; } } return SUPER::Message(node, type, data);

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