CUTTING THROUGH THE FOG

Ninja is running a raw simulation under the hood: “density is white, lack of density is black” --- and this raw simulation becomes water, or fog, or clouds - depending on the Output Material. The good mindset is to think about the visualization “as a display” (could be anything - fire, water). Also, it is the simulation that interacts with the input objects (meshes, particles) --- so, when we see an object “cutting through the fog” --- the fog volume is just a display, the object does not interact with the fog: it interacts with the sim container, that detects its movement, writes its trajectory to a raw sim buffer - and we can visualize this raw buffer different ways.

Key: the Display Concept: See Manual Chapter 4.8 and Tutorial01_Basics.umap / Stage 9 to learn more.

Considering the above: in case our system is “fluidsim driven” (not passive): we can make anything “cut through the density” --- and display it as fog (FVOL) or heterogeneous volume (HVOL) or clouds (CVOL).

Examples:

• Clouds.umap / Setup-5, Titan: we are using Inverse brush density - and cutting through the clouds.
• Clouds.umap / Setup-6, CloudPainter: we are using positive brush density - and painting clouds.
• Similar examples could be found on the FVOL and HVOL demo levels, in the Levels /Misc Folder.

The key param is /LiveComponent /LiveInputFields /InvertFieldAndPointDensity - switching between eraser and positive mode.

Alternatively, we can also go neutral: not adding and not removing density - only injecting the velocity of the moving object to the sim, so it stirs the fog / fluid: see /LiveInputPoints /BrushKillers /SelectivelyKillBrushDensityKeepVelocity