I will show how to hide an object based on the selected style.

I created a style tree that looked like:

Base
|
- Triangle
|
- Rectangle

In base I created two object with unique names to avoid confusion:

• Rectangle Object'
• Triangle Object

Then I added the following code point to base

if ( Flow[ @Piece[Base] ] == @Style[Rectangle] )
  @Object[Triangle Object].Hide = 1; 
else
  @Object[Rectangle Object].Hide = 1;

There is a lot going on. Let me break it down.

@Object[Triangle Object].Hide = 1;

and

@Object[Rectangle Object].Hide = 1;

A lot is added in

if ( Flow[ @Piece[Base] ] == @Style[Rectangle] )

To break it down.

@Style[Rectangle]

Every style is converted into a unique number. This code is getting the number for the style Rectangle.

The same is true for pieces. To get the piece's number we use

@Piece[Base]

Understanding that we can look at the .mac file and find the following code.

if ( Flow[ 0 ] == 2 )

This is straight C code testing if an array value is equal to a
constant. The key here is the options chosen when running the macro
populates the Flow array. There is one element for each piece. Flow[0]
corresponds to the first Piece (Base). If we added another piece it would have the value 1.

The value of Flow[0] contains the unique value of a style. There are 3 styles in Base. They are:

• Base
  • Triangle
  • Rectangle

While it is possible to hard code the values it quickly becomes confusing. Accessors make the code more readable.

Here is the final project HideObject.mg4 (23.8 KB)