Batching Material Replacement

V-Ray V-Ray for SketchUp General
1

Is there a way to batch render material swap? For instance, I have to render a chair, but I have to render it in 37 seat fabrics. I know I can do a region render and just render the seat over and over. But it’s still the process of swapping the fabric and hitting render again. Any way to batch it so it’s just Render > Swap Fabric > Render > Swap Fabric > etc… ?

2

Hi @igendreau ​,
You can write a Ruby script that does the swapping and rendering automatically.
Getting familiar with the SketchUp and V-Ray APIs is going to be required though.

3

I think the function he wants is to only render objects with a specific ID or objects with a specific material.

4

Hi,

We’ve prepared a script that you can try.

First you need to prepare your scene:

1.Create a Wrapper material and apply it to the parts of the chair you want to swap the materials of. The script will use the first Wrapper material as an identifier of what needs to be replaced.
2. Add “Replacement_” in the name of each material variation (for the materials you want to be replacing with).​
​
Then you can run the following to implement a subscriber:


class MySubscriber
  def initialize(context, path, materials)
    @context = context
    @path = path
    @materials = materials
    context.subscribe(self)
    context.renderer.subscribe(self)
  end
  def on_model_exporter_created(model_exporter_created)
    model_exporter_created.subscribe(self)
  end
  def on_model_exported(exporter)
    renderer = exporter.renderer
    wrapper = renderer.grep(:MtlWrapper).first
    material = @materials.pop
    exporter.export_material(material)
    wrapper[:base_material] = renderer["/#{material.display_name}"]
    puts wrapper[:base_material]
    settings_output = renderer.grep(:SettingsOutput).first
    settings_output[:img_file] = "#{@path}/#{material.display_name}.png"
    puts("#{@path}/#{material.display_name}.png")
  end
  def on_state_changed(renderer, old_state, new_state, instant)
    if @materials.empty?
      clean_up
    elsif new_state == :idleDone
      next_render
    end
  end
  def next_render
    VRay::Command.render_production(context: @context)
  end
  def clean_up
    @context.unsubscribe(self)
    @context.renderer.unsubscribe(self)
  end
end​

Now run this second script.


context = VRay::Context.active
path = ENV['HOME']
materials = context.model.materials.select { |m| m.display_name[/Replacement/] }
MySubscriber.new(context, path, materials)

Start a production render using the toolbar teapot icon.
The scene is going to be rendered multiple times, once for each material Replacement_.

Additional notes:

1. Replace the path value in the second script with an output folder of your liking. If you don’t do that, the output images will be saved in C:/users/user
path = “C:\temp\chair_renders”

2. Change the /Replacement/ string in the second script with another keyword if do not want to use the default one.

3. Rerun the second script to render a batch again. Otherwise a regular render will be performed.

Let me know if that works for you?
Konstantin