Visual diffs

[brunopostle]

Visual diffs highlight 3d blender objects that have corresponding IFC entities that have changed or that are new between revisions. This is extremely fast as it doesn't involve any IFC parsing.

It isn't looking any deeper, so in practice the object will only be highlighted if its name, location, or representation etc.. is different ie. it is literally only looking to see if the entity text has changed. As it happens, BlenderBIM will always create a new representation or location entity whenever there is a change, so this works, for now. It wouldn't be hard to look a bit deeper and check to see if entities that reference or are referenced by the 3d element have changed, and this would give a bit more coverage.

A nice feature would be to be able to select a highlighted 3d object and view relevant commit messages in place.

Regarding pure non-3d data, the add-on knows which entities are changed/added/removed, but there is no obvious way to show this in BlenderBIM because the data is presented in different parts of the GUI (if at all). We could offer a list of entities and browse them by ID in the IFC debug panel, but that would be no fun :(

Note that a potential feature would be to collect the bounding boxes of modified/new objects, flatten and merge them, and use these to automatically generate revision clouds in generated drawings.