The Subtract Tool

Let’s say you’re designing a venue with a slightly nautical theme. Think portholes, think sunlight streaming in through a series of round windows cut evenly into the walls of the room. With the new Subtract tool in R20, cutting holes in walls is fast, clean, and precise, kind of like having a virtual chainsaw with a very fine blade.

In this procedure, you will cut a series of round “windows” into the walls of your venue using the new Merge Objects feature. The Merge Objects series of tools enables you to choose two different sets of objects and then perform one of three actions on them:

• Subtract Objects This option enables you to select two sets of objects, and then subtract the overlapping area of the second set from the first set that you chose.
• Unite Objects This option enables you to join the two sets of objects together as one, merging their common area so that it is indistinguishable from the original objects.
• Intersect Objects This option enables you to choose two sets of intersecting objects and then delete everything outside of their common area.

To cut holes in walls with the Subtract tool

In this procedure, you use the Subtract tool to cut a line of round windows into two opposing walls of your venue.

1. In the CAD Mode > Drawing Quad tab, draw a venue (for example, a black box).
2. Click the venue to select it, and then right-click and choose Tools > Break > Solids into Surfaces.
   • Note: Since the window shapes are a series of 2D surfaces, it is best to convert the 3D venue into a 2D surface as well. This way, the window shapes only have to project onto the “walls” in the same plane. If the venue is a 3D object, then the windows would have to physically touch them (intersect) before you perform the Subtract operation.
3. Click to highlight the Front view quadrant.
4. Click the Circle tool, and then click OK to accept the default size of 4’.
5. In the Front view quadrant, click to place the circle half-way up the wall, at one end of the room, as shown below:
6. With the circle still selected, right-click and choose Tools > Convert > Circles into Surfaces.
7. Type 20 and click OK. (The higher the number of points, the smoother the outline of the circle.)
8. With the circle still selected, click Tools > Array > Linear.
9. In the Front view quadrant, click the extreme right-hand wall to pick the destination point.
10. Type 3 for the Number in row and 20 for the Interval, and then click OK.
    • Result: The circular surfaces are arrayed along the length of the room.
11. In the Front view quadrant, click the Black Box outline to select it, and then click Tools > Merge Objects > Subtract.
12. Click to select all three circular surfaces at once, and then right-click and select Finish Subtract.
    • Result: The circular windows are “cut” into the walls of the venue, as shown in the following graphic:
13. When you design and render the file, it could look something like this: