Outside / Inside

In Lesson 14 I had already discussed the difference in color of the outside and the inside of a figure in SketchUp, but to elaborate on this, sometimes the result is not what it should be.

For example, we have a cube with a circle drawn on one side.
When we push the circle off to form a cylinder, there is no problem, the exterior of the cylinder is white, just like the outer surface of the cube, so far so good (1).
When we push the circle into the cube, it will be colored blue (2), same as the inside of the cube. There  is no a problem here also.
However, when we push the circle through the cube there’s a error (3). When looking at the cylinder pushed outside of the cube, it still remains in blue color.

When you change the color of the cylinder that protrudes outside of the cube, as seen in lesson 14, it would alter the color of entire cylinder, that is the part inside the cube also, which is not good.

Those of you that have carefully followed all classes till now, will know that it is normal that the color of entire cylinder changes, and this for the simple reason that it consists of one part, and thereby when we right click and select it, it’s selected fully.

In other words, we need the portion of the cylinder located outside the cube, and the portion of the cylinder located inside the cube, split or cut, into two separate parts.

 

We have already seen how to do this in two overlapping 2D circles in Lesson 8,”Intersecting faces,” remember?

 

The cutting of 3D Figures

Well, we need to do the same for 3D figures.
We know that the cylinder is made of a circle, we know that a standard circle consists of several segments, standard 24.

In other words, our cylinder consists of 24 segments.
When we zoom into our cylinder clearly, you see the different segments, indicated by the text “Intersection”, when you move the mouse pointer over the edge between the cylinder and the cube.

What you would do is take all of these segments one at a time and click with the Line tool, so that the portion of the cylinder that is inside of the cube, is separated from the portion that is situated outside of the cube.
But this can be faster.
Right-click above the cylinder and select “Inresect” select “Intersect with model” in the drop-down menu.
Our cylinder is now divided into two parts.
Now you already know how you need to change the color of  the inner part.

Another tip.

Is your figure very spoiled with white faces and blue areas, you do not have to change each color to the right color with the “Reverse Faces” (Reverse Faces) option, as we saw in the beginning of this lesson, but we have another option that replaces all these colors at once.
Right-click a plane with the correct color, and select “Orient Faces” (Orient Faces) in the dropdown menu.

All surfaces are in white color.

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