Rocks and Stones

There came a question if it is possible to create rock and stone models in Silvador. It actually wasn't, but it makes a good sense to allow that: Just like plants, shape of stones is driven by controlled randomness to big extent. Just like plant models, also stone models can benefit from easy LOD creation and shading precalculated in textures. Therefore version 1.54 comes with extension of Volume component that allows that.
The Volume component on its own allows creation of closed geometry and one can produce shapes like this:

In 1.54 there is something new: There are new attributes hNoiseOctaves and array hNoiseAmplitude. By using those it is possible to apply cascade noise on position of the volume vertices. hNoiseAmplitude is an array that allows controlling of individual frequencies, thus it is possible to apply just low frequencies:

... or just high frequencies:

... or all frequencies:

... which is already not that far from what we want to achieve - a stone.
So much about shape. But there came a bigger challenge - texture mapping.
For convenience of artists and to respect existing infrastructure in usual game engines, we must apply 2D texture on the surface. The default mapping of Volume component is Cylindrical mapping. Unsurprisingly, it is producing 2 ugly singular points on typical stone, like this:

After number of experiments f.i. with triplanar mapping, we settled with something called Conic mapping, where top and bottom hemisphere is mapped with the same but mirrored texture. This is how it started to look:

User can choose between those 2 mappings by a new attribute projectionType. The above conic mapping is also not an ultimate solution. It transfers the singular point artifacts to mirror artifacts like this:

But that is already something we can fight with. The same way we apply noise to height of given vertex, we can also move it forward and to the side and hide the mirroring. Attributes that control that are called uNoiseOctaves, uNoiseAmplitude, vNoiseOctaves and vNoiseAmplitude. This is what we get then:

Few results with applied lighting: