4.4.1 Limits on sketch error detection

Sketch catches many kinds of errors, but not all. For example, options that sketch does not recognize, even incorrect ones, are quietly copied to PSTricks commands in the output. It is also unfortunately easy to produce sketch inputs that lead to no picture at all (improper vertex ordering causes everything to be culled), to pictures that are too big or too small for PSTricks to draw (due to limits of TeX math), and pictures that look nothing like what was intended. A picture with one of these problems can be difficult to “debug.” We offer the following suggestions.

• Follow the suggested incremental development method described in Overview.
• Always maintain one or two back-versions of a drawing so that it is easy to fall back to a known-good increment.
• When using perspective, ensure all finally transformed objects satisfy z<0 and, in fact, do not come very close to the origin at all.
• Temporarily use cull=false to see where vertex ordering problems lie.
• Use temporary changes of color of one or more objects to ensure that your understanding of the scene geometry is correct.
• If PSTricks complains about something, inspect the output directly for clues.