CUBIZEN: Global Mapper, CityEngine & Creative Tech

How Scope Direction Affects split() Operations

As I mentioned previously, the reason for changing the scope is to perform operations like splitting, moving, and scaling in the desired direction.

Today, we will use rotateScope() to rotate the scope and see how the results of split() change accordingly.

@Group("Select_Axes", 0)
@Enum("world.xyz", "x", "y", "z")
@Description("Select which axis to align the scope to.")
attr AlignScopeToAxes = "world.xyz"

Lot -->
    primitiveCone(5, 5, 20)
    # Generate a cone
    alignScopeToAxes(AlignScopeToAxes)
    A

A -->
    split(y) { '0.25 : B }*
    # Split into 4 equal parts along the Y-axis

B -->
    case split.index == 0 :
        color(1, 0, 0) X.
        # Paint the first split segment red
    else :
        X.

On line 15, there is a split(y). Since split(y) operates along the local Y-axis of the current scope determined by alignScopeToAxes on line 11, you should pay close attention to how the splitting angle changes.

Video demonstrating the interaction between alignScopeToAxes and split

However, scope alignment alone has its limitations.

Using rotateScope() for Diagonal Splits

Let's use rotateScope to change the split() angles in various ways.

As the name suggests, rotateScope() allows you to rotate the local scope around the X, Y, and Z axes.

How rotateScope Changes Local Scope Axes

@Group("Select_Axes", 0)
@Enum("world.xyz", "x", "y", "z")
attr AlignScopeToAxes = "world.xyz"

@Angle
attr rot_X = 0
@Angle
attr rot_Y = 0
@Angle
attr rot_Z = 0

Lot -->
    primitiveCone(5, 5, 20)
    # Generate a cone
    alignScopeToAxes(AlignScopeToAxes)
    rotateScope(rot_X, rot_Y, rot_Z)
    # Rotate the scope based on attribute values
    A

A -->
    split(y) { '0.25 : B }*
    # Split along the Y-axis of the rotated scope

B -->
    case split.index == 0 :
        color(1, 0, 0) X.
    else :
        X.

Step-by-step video of scope rotation and alignment

In the video, we only performed a simple test.

Understanding World Axes and Local Scope

After typing the code above yourself, you should refer to the world axes in the bottom left, change the axis and scope values, and carefully observe and understand the relationship between them.

For those who have studied coding a bit, it would be even better to check how position movement works according to axis and scope changes using the t() command.

alignScopeToAxes is the easiest and most straightforward method among scope alignment techniques.

Limitations of alignScopeToAxes()

This is because it uses only a single element, the 'axis,' as the reference for setting the scope.

However, as you build things, there are times when you need to attach the scope to elements other than the axes.

For example, setting a scope based on the sloped surface of a roof,

or in the case of the pentagonal pyramid in the video above, setting the scope based on the third face is difficult with alignScopeToAxes(). (It's not impossible; you could set the angle using rotateScope, but you would have to readjust it if the size of the pentagon changes.)

That is exactly why we need alignScopeToGeometry(), which we will cover in the next lesson.