Welcome to the tutorial on Single Criterion Optimization using Galapagos, a plug in for Grasshopper which is written by David Rutten. 

For the design problem, we are imagining the following scenario you're tasked to design the roof of a courtyard in which you will need to place openings. These openings should be placed maximize the direct light shining on the terrace below. In the following chapters we will discuss a method to optimize the location of the openings. 

In order to set up our script, we will need a few pieces of geometry. First, we will need to place the terraces. We can model these as surfaces in Rhino and then we will need to link them into Grasshopper. To link them, we want to select the Surface icon which is located on the Parameters menu under Geometry. We will also want to label which surface we are linking. To create a panel, double click and press the forward slash twice. Type in the word terrace and hit Enter, to create the label for our node.  

Then to link the geometry, we can select the component right click and set multiple surfaces. We have two surfaces in our Rhino model. Select one of the surfaces and make sure to hold shift while you select the other. Then press enter in Rhino and this will return you to the Grasshopper interface with the surfaces linked. 

We can see that the geometry is linked because the component is now gray in color. Next we will want to link the geometry for the roof. You can create any roof shape that you like. If you want to follow along more closely using the same slider values as the tutorial, ensure that the width of your roof is twice the depth of your roof and this is specifically when viewed in top view. 

For example, here our blue roof is 20 meters long and 10 meters wide. The profile of the roof can be any shape. In order to link this, we can simply copy and paste these components and make sure to update the label to roof. Then we can right click the surface component and this time we're only setting one surface which is our roof surface. We can move this up to the top and finally make the geometry for the opening.  

The opening can be modelled as a flat surface located above the roof surface. Since our roof is curved, we're going to project the opening onto the roof. To follow along with the values used in this tutorial, make this opening twice as long as it is wide. We are using 400 mm wide by 200 mm deep. We can again copy and paste the component from the roof. This time we will update the label to state opening. We can right click the surface component, set one surface and set our opening geometry. Once all these elements are linked, we can go ahead and hide the geometry in Rhino. So you can see now all geometry is red, they are linked with Grasshopper.