Rhinoceros or Rhino as it is commonly called is primarily a NURBS modelling tool used for industrial design (vehicle design, jewellery design, product design) and architectural form finding.

The word “NURBS” stands for Non-Uniform Rational B-Splines. NURBS are a mathematical model commonly used in computer graphics for generating and representing curves and surfaces. NURBS offers great flexibility and precision for handling both analytic (surfaces defined by common mathematical formulae) and modelled shapes and for this reason they are industry standard for both modelling and manufacturing.

The alternative to the NURBS type geometry definition is called MESH Modelling. Meshes represent a surface using polygons: high accuracy modelling requires a large number of polygons, so the mesh models can become very large. Therefore, meshes are used more for visual modelling rather than fabricated ones.

Images sourced from: https://education.graphisoft.com/mod/book/view.php?id=155&chapterid=1232

Grasshopper is a visual programming language and environment that runs within the Rhinoceros 3D computer-aided design application. Grasshopper is predominantly used for parametric modelling for design, architecture, structural analysis and fabrication.

Parametric design is a process based on algorithmic thinking that uses parameters and rules together to create designs. The parameters and rules can be used to manipulate and change the form in real time.

In grasshopper is important to note that you will most commonly be working with NURB surfaces and NURB curves.

NURB curves are defined by degree, control points, and knots.

Degree: The degree is a positive whole number. This number is usually 1, 2, 3 or 5, but can be any positive whole number. The degree of the curve determines the range of influence the control points have on a curve; where the higher the degree, the larger the range. NURBS lines and polylines are usually degree 1, NURBS circles are degree 2, and most free-form curves are degree 3 or 5.

Control Points: The control points are a list of at least degree+1 points. One of the easiest ways to change the shape of a NURBS curve is to move its control points.

Weight: Control points have an associated number called a weight . Weights are usually positive numbers. When a curve’s control points all have the same weight (usually 1), the curve is called non-rational, otherwise the curve is called rational. Most NURBS curves are non-rational. A few NURBS curves, such as circles and ellipses, are always rational.

Knots: Knots are a list of (degree+N-1) numbers, where N is the number of control points.

Edit Points: Points on the curve evaluated at knot averages. Edit points are like control points except they are always located on the curve and moving one edit point generally changes the shape of the entire curve (moving one control point only changes the shape of the curve locally). Edit points are useful when you need a point on the interior of a curve to pass exactly through a certain location.

Images sourced from: https://education.graphisoft.com/mod/book/view.php?id=155&chapterid=1232

If you have Rhino 6 and onwards you will be able to access grasshopper by selecting the Grasshopper icon from your main tool bar in rhino. Otherwise you can simply type GRASSHOPPER in the command bar.

This will bring up the a basic interface for grasshopper. We have the main toolbar when you can save and load files, undo/redo, change the display settings and user interface etc. We then have the toolbar for parameters and components that are organised into different categories. There are a range of subtabs organising components into similar groups.

There is also the Canvas where the grasshopper definitions is created.

There is more information about how to use lists and data trees below.

There are three plugins that are a great starting addition to any beginner in grasshopper ready to experiment further. Most plugins can be downloaded from the website for free called – Food4Rhino https://www.food4rhino.com/en. Weaverbird is linked below from their own website.

Weaverbird- Weaverbird brings mesh editing, subdivision and mesh transformations to Rhino and Grasshopper users.

Lunchbox - LunchBox is a plug-in for Grasshopper for exploring mathematical shapes, paneling, structures, and workflow.  We have also introduced new components for general machine learning implementations such as regression analysis, clustering, and networks. Note: Lunchbox is only supported on windows, however I managed to download an older zip file version that installed fine on a mac.

Pufferfish - This plugin is a set of 330 components which focuses on Tweens, Blends, Morphs, Averages, Transformations, & Interpolations - essentially Shape Changing. Pufferfish mainly uses parameters and factors for inputs for more custom control over operations like tweens and grids as opposed to grasshoppers usual division count inputs.

Components, parameters, and functions can all change colour based on whether it is functioning correctly or not.

Light grey - Represents a working component with no issues, if it is geometry, it will also be visible in Rhino.

Dark grey - Represent a hidden component (not visible in rhino), although this still means what even function is completely is still completely active within the grasshopper script and working.

Orange - Orange represents a warning signal, this could be a missing input, such as forgetting to reference a point from rhino, leaving the parameter empty or having a mismatching data. In some cases, the component will still be functioning but is close to failing and should be investigated. If you click on the orange balloon it will give you a hint of what is wrong.

Red – Red represents when a component or function is not working as it is supposed to (an error has occurred). Typically, what occurs here is the wrong type of geometry or data has been plugged into the wrong input. In the image below a surface has been plugged into the point container which is the wrong input type. There is a range of errors that can occur, so make sure to check the balloon for assistance.