Hi, lately I have been trying to figure out how to use the trois crayons (three chalk) approach. The images show a drawing I used as reference and my attempt. Sadly I cannot remember the original artist of the reference image. It is unclear to me, how to decide, which areas to consider as cool (black) and which areas to consider as warm (sanguine). Is there any approach or rule that has been particularly successful? For example: "Always keep the cast shadows and core shadows cool and form shadows warm." I couldn't figure out any logic like that behind the choice of colour temperature in the reference drawing. Any inside or thought on that topic is appreciated. Thanks in advance. - Philipp