Google SketchUp: The Missing Manual

Creating Images for New Sketchy Edge Styles

So how do you teach a computer to draw lines that express a human, random, hand-drawn look? The trick is to split the workload. You draw some sample lines, and then you let the computer modify and apply your lines to models in a way that seems random.

Style Builder expects you to provide samples in a certain format called a stroke set. Each stroke set has a specific length in pixels. Computers like numbers divisible by 8, so typical set lengths are 32, 64, 128, 256, and 512 pixels. You can provide several strokes (line samples) for each of those lengths, so you might end up with a few sets that look like those in Figure 15-2. It's your choice exactly how many strokes you provide for a set. Something between three and five strokes per set is reasonable. The more strokes you provide, the more SketchUp gets to work with to create a random appearance. You need to provide the same number of strokes for each set. So if the 32-pixel set has three strokes, then all the other sets must have 32.

Figure 15-2. Strokes come in sets of certain pixel lengths. This set has three line samples for each of five different lengths.

To create stroke samples, you can draw them on paper and then scan the images into your computer, or you can create the strokes in a graphics program like Photoshop that provides calligraphic brushes. The use of a pressure-sensitive ...