Scene Rendering
After adjusting the quality of the destruction and smoke sim, I rendered the scene and composited it in Nuke this week. Then I added some sound effects in it. Here is the final result:
Procedual Saliva HDA
After that I started to make another visual effect, which is a procedual saliva digital asset.
Saliva is an important element of realistic creatures. For example, we can find creepy saliva effects in film Alien (1979) and The Thing (1982), which brings a great sense of realisim and horror.
I firstly find some saliva reference:
As we can see, saliva can be separate into 3 types:
- Filamentous dropping saliva
- Punctual dropping saliva
- Filamentous dangling saliva
Filamentous dropping saliva and punctual dropping saliva can be easily simulated by using high viscosity fluid sim and surface tension. However, filamentous dangling saliva can not be easily achieved by using fluid sim. It is more like a fluid-like cloth simulation. What’s more, the shape of saliva has some regular patterns: both sides of saliva is thick and the middle of it is thin. Such kind of feature shows a sense of high viscosity.
I used a combination of vellum cloth and VDB to sim filamentous dangling saliva. The main idea of it is to build up lines using VEX, and then use vellum solver to sim these lines. After that I turned lines into particles and then turn them into VDB, and finally convert them back to polygons.
This is a procedual method of building saliva. Therefore, I can easily build saliva on different creature models by using the HDA. What’s more, I can change the shape and numbers of saliva by using customed attributes.
I did a simulation to test the result. Most part of it works well. However, a bending can be easily found on the saliva when the the mouth is closing. This can be a problem because it makes the saliva more like a cloth rather than a fluid. I think the problem comes from the vellum simulation. I need to add more elasticity to the sim to prevent this kind of results.
After that I optimized the volume of saliva, here is the result:
A rendering for the saliva:
A movement test for the saliva: