Relevant to Blender v2.31
What you see in (Figure 29.17, “Caustics setup.”) is a completely ic image realized by Xavier 'richie' Ligey, modelled with Blender and rendered with YafRay. The export has been made with Yable. There is no light at all in the scene, only a Hemi Light with an HDRI background. Xavier has been so kind as to give us the screenshots of the settings he has used in Yable.
A special thank to Alessandro Braccili, who helped me in Yable/YafRay understanding, and in the writing of this chapter.