CUBIZEN: Global Mapper, CityEngine & Creative Tech

Workflow Overview: CityEngine CGA to SketchUp RPK Pipeline

It is said that CityEngine CGA files can be used in SketchUp, but in conclusion, it does not work well. The items included during installation work fine, but when trying to use custom-made ones, SketchUp ends up force-closing. Since I haven't used SketchUp much, even looking at GitHub, there are no bug reports at all, so I don't know what the problem is. Nevertheless, I will proceed with calling the CGA extension in SketchUp for now.

Even though it failed, it's better to leave the process recorded.

First, the way it works is as follows:

• Complete the CGA code in CityEngine.
• Convert it to an RPK (Rule Package) file using "Share As."
• Install the CityEngine-Sketchup-Extension.
• Use it in SketchUp.

Preparing CGA Rules in CityEngine

@Range(min=6, max=30, stepsize=1)
attr BD_Height = 10
# This is the building height attribute.

@Range(min=3, max=5, stepsize=0.5)
attr Floor_Height = 3
# This is the floor height attribute.

@Color
attr Floor_Color = "#FF0000"
# This is the color attribute.

@StartRule
Lot --> extrude(BD_Height) BD
# Assigns height based on the BD_Height attribute value.

BD --> split(y) { ~Floor_Height: Floor }*
# Splits the floors by the Floor_Height.

Floor -->
    case (split.index % 2 == 1):
        color(Floor_Color) X.
    # Colors odd floors with the Floor_Color attribute.
    else:
        color("#00ff00") X.
    # Colors the rest in green.

Exporting CGA as RPK Package

As a result, this is the CGA code that causes an error in the SketchUp extension, but it is a file that raises a building by setting the building height, floor height, and color as attribute values. Even floors are colored red, and odd floors are colored green.

This is the screen showing the applied Rule. Now, let's create the RPK file.

Select File - Share As.

A screen appears to select which CGA file to convert into an RPK.

When you select the CGA file you just created and click Open, a window asking for the save path appears.

You can add a description for the RPK, and if 3D files or images were used in the CGA, you should include those folders as well to package them into the RPK.

Once settings are complete, click Analyze to verify there are no errors in the CGA code, and if there are no issues, click Share to save it.

Now it's time to install the CityEngine-Sketchup-extension. Note that the SketchUp version must be between 2017 and 2022.

After downloading and installing the extension from the path below:

https://github.com/highered-esricanada/CityEngine-Sketchup-Extension

Installing CityEngine SketchUp Extension

Copy the RPK file you just created into the C:\ProgramData\SketchUp\RPK folder.

Running RPK in SketchUp

Now launch SketchUp. For reference, I have installed the 2022 version. When you select "Show CityEngine Window" in the Extensions menu, a window will pop up.

Since the custom-made one keeps failing, let's test the default RPK file that was installed initially.

Video demonstration showing the successful operation of default RPK files in SketchUp.

Troubleshooting Custom RPK Failures

Why does the default RPK work well while the custom-made one causes errors? I thought about trying Bridge, but we will explore that when we cover the CompleteStreetRule package during CGA coding sessions. From the next lecture, the full-scale CGA coding begins.