written by Nathan 'jesterKing' Letwory
To create a specific material type we are going to use
RenderMaterial from the
In this example we'll create a Paint material. To do so we'll need the type
GUID. The different type GUIDs can be found under
properties. In our case we need
A new instance we create with one of the static method
Using one of these overloads will result in the material being created and
added to the persistent content list. In other words it will show up in the
The script will be implemented as a script, not a command. It will import the necessary modules and namespaces. It'll take note of the currently selected objects. Then it will create a Paint material with random color assigned to it. Finally the new material will be assigned to each of the selected objects.
<<import necessary libraries>> <<check for an object selection>> <<if object selection exists create material and assign>>
We need access to the
Rhino.Render namespace for the material and render
content related classes. Further we want to access the document. For that we are
going to use
scriptcontext. We'll import just the namespaces or modules
meaning we'll have to include these when using classes and functionality they
provide. We're doing that for this script to make it clear where the used bits
and pieces come from.
To create a random color we'll need the
random module along with access to
Color4f from the
import System import Rhino.Display import Rhino.Render
import scriptcontext import random
We'll keep the next part of the script simple. We're not going to ask the user to select anything. Instead the script relies on the selection already being made. We still create a material, but without a selection no assignment will be made.
# get object selection object_selection = [ob for ob in scriptcontext.doc.Objects if ob.IsSelected(False)]
We'll create and assign the material only when there is an object selection.
# only if we have a selection do the work if object_selection: <<create a paint material with random color>> <<assign the material to the object selection>>
To create the material we use
RenderContent.Create. We don't need much else
besides the render content GUID and the document.
Once we have a material we need to bracket any changes we want to make between
EndChange() calls. Otherwise Rhino will ignore any
programmatical changes to the render content because it is already in the
document after creation.
We set a name suffixed with a new GUID each time this material is created by the script. This so we don't end up with materials that have the same name. While it is possible to do so with a script names should really be unique.
# create material render_material = Rhino.Render.RenderContent.Create( Rhino.Render.RenderMaterial.PaintMaterialGuid, Rhino.Render.RenderContent.ShowContentChooserFlags.None, scriptcontext.doc) render_material.BeginChange(Rhino.Render.RenderContent.ChangeContexts.Program) render_material.Name = "PYSCRIPTCREATED " + System.Guid.NewGuid().ToString() random_color = Rhino.Display.Color4f( random.random(), random.random(), random.random(), 1.0) render_material.SetParameter("color", random_color) render_material.EndChange()
Now that we have a material we can assign it to each object in our selection.
For Rhino to notice changes to objects in the document we need to do something
similar like the method above for changing render content that is already in the
document. We have to
CommitChanges() on the object for the changes to stick.
# assign for ob in object_selection: print("Adding material", render_material.Name, "to", ob) ob.RenderMaterial = render_material ob.CommitChanges()
It is relatively straightforward to programmatically create new render content in Rhino. There are a few mechanisms the programmer needs to be mindful of: bracketing of changes to render content, and explicitely committing changes made to document objects.
Note that this particular implementation does not really check whether it is
useful to even have a
RenderMaterial assigned. It would be good to add that
Furthermore the script could be improved with a piece of code that actually queries the user for object selection if none has been made.
These improvements are left to the reader to implement, as the main goal here has been achieved: show how to create and assign a new material of a specific type.
The generated script is in the repository here