Grasshopper Interface
Starting Grasshopper
There are two methods to start the Grasshopper plug-in in Rhino. You can type 'Grasshopper' in the command line, but it can also be opened by clicking on the Grasshopper icon.
The Grasshopper interface contains:
- A row of pull-down menus
- Tabs with parameters, utilities and components
- Toolbar
- the main workspace or canvas
The canvas is used to create your network – your ‘recipe’. This network is built from parameters, utilities and components. This network in turn will create your model (geometry) in the Rhino viewports. Note that all geometry generated by Grasshopper can’t be selected and modified in Rhino. Geometry created in Rhino however can be used by Grasshopper. We’ll get back to this later.
File
The file menu contains the traditional options for saving and opening files. Note that Rhino and Grasshopper files are always separated. You save your network in the Grasshopper window. If you have used Rhino geometry as a basis for your network, you have to save the Rhino model separately in the Rhino window!
Edit
In the Edit option we have the standard copy, paste and selection options as well as the options of grouping. Grouping is essential when the complexity of the network increases
- The group is often a set of parameters / components / specials which generate a well defined function within the network. The group can also be defined by selecting the parameters , components and/or specials and press CRTL+G on your keyboard. Right clicking with your mouse in the box of the group gives you access to the appearance settings of the box.
View
View contains the view options within Grasshopper like zoom. It also contains various options to control how your network is displayed on the canvas. We’ll get to these when needed.
- At the top we have the Remote Control Panel This option will hide the grasshopper canvas and provide you with a smaller menu where all the variables can be accessed. This option is used when you want to avoid that the menu of Grasshopper will block your view of the geometry.
Display
The display menu holds all options to display your script. For example, in the tutorials of the wiki, nodes are always drawn with icons and Full Names of inputs and outputs are visible. You can change all your preferences in this menu.
Specifically useful are the Canvas Widgets on the bottum of the menu. You can use the profiler widget to view the calculation speed of your script.
Solution
The Solution menu contains the settings for the geometry generated by Grasshopper and made visible in Rhino.
- There is a direct link between Grasshopper and Rhino which results in a real-time update of the geometry in Rhino, this is called the preview. This however can be problematic if the complexity of the geometry results in to extensive calculations for the update of the geometry. In this case the update can be disabled.
- To finalize the work in Grasshopper geometry has to be converted into Rhino geometry. This is called baking. The geometry will be completely editable in Rhino after baking. Although the link with Grasshopper still exists the baked geometry is a copy of the Grasshopper geometry at the moment of baking. Any alterations in Grasshopper will result in alterations of the Grasshopper geometry not of the baked geometry.
The Tabs
The building blocks that you use to build your network are arranged in various tabs:
- Parameters
- Math - for creating mathematical relations
- Set - List tab where the list can edited
- Vectors, Curves, Surfaces and Meshes
- Intersect
- Transform
- Display
Grasshopper is actively being developed, so this may change from version to version. Each tab is divided into sections to group similar building blocks. Each section shows the most-used blocks. The arrow at the right-hand side of the black section title bar allows you to expand the section to show all available blocks.
The Canvas Toolbar
The icons bar beneath the Tabs contain the functions for representation of the network and its related geometry in Rhino.
The Pencil
The Pencil icon enables the user to draw in the Canvas. This tool can be used for annotation or, for example, to encircle certain related parameters and components to emphasize their relation.
If the curve is right clicked an option menu will appear with edit functions for the curve. The hand drawn curve can be replaced by a curve made in Rhino by using the Load from Rhino option.
The navigation within Grasshopper is supported by the various zoom and pan tools in the icon bar. Traditional navigation is supported by Right Mouse Button (Pan) and CRTL + Right Mouse Button (zoom). Additional functionality is supported by the icons.
Preview
When something is made in Grasshopper a preview of the geometry is created as a Brep in Rhino. The preview can be disabled or a selection of components can be disabled to save for example calculation time or cleanup the Brep in Rhino. By selecting some nodes and clicking on the middle mouse wheel, you can access options to preview, enable, group and cluster your nodes. This is also possible by selecting the nodes and then RMB on the selection.
Solution
The Brep in Rhino is a preview of the geometry made within Grasshopper. To icons on the right give access to the relational settings of the Brep with Grasshopper. To convert the Brep into Rhino geometry the geometry has to be baked with the help of the bake icon.
In the solution bar, you will see some options for mesh representation. Meshes can be calculated using the graphics card of your laptop, and will therefore be visible way faster than normal Breps. By changing the mesh preview, you can change the quality and speed of your viewport.
The Canvas
Although you can add nodes by clicking on them in the component tabs, you can also double click LMB on the canvas and enter the name of the object.
Baking
As mentioned earlier, geometry from Grasshopper is not selectable or editable in Rhino. To be able to do this, you will have to 'bake' your geometry. Usually, a script developer works according the following procedure:
- Generate input data for the script in Rhino
- Develop a script in Grasshopper
- Finding the right settings for the model using the available parameters
- Baking the geometry back into Rhino
A comprehensive explanation on how to bake geometry, can be found in the first Grasshopper tutorial: Basic Principles Explained.
