How to do Color Mixing in VDB Drop 8 (thinkingParticles)
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How to do Color Mixing in VDB Drop 8 (thinkingParticles)
Mission: Four color fluids colliding with sprays of liquid particles and authentic, physically-correct color mixing.
Keywords: color diffusion effects such as color bleeding effects, color mixing, temperature mixing, diffusion within volume (available in FlowSolver since thinkingParticles 6.7. Please watch videos @ https://vimeo.com/showcase/4970668)
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In this scene, we will teach you how to use thinkingParticles Drop 8 Open VDB operators to create fluid particles colliding in 3dsmax real time, no gravity.
DYNAMIC SETUPS – ObjectToParticle : Four emitters (for 4 color fluids) and point helpers for the coordinates. Each E,itter to PGroup 1,2,3 and 4 respectively.
– 4 Color Streams Emitter #1, 2, 3 and 4 as shown. Emittter particles o/p to Flow Emitter / particles and Flow Emitter/ birth particles o/p to Data Channel / particle color (stores color from Helper Color).
– Set your parameters / values such as diameter of fluid stream, amount of particles desired etc. – helper Color (select color) i/p. use Subgroup Mix: Group 1,2,3,4. So each particle can stream its own color. – Helper Float value o/p to all 4 Flow Emitter / Raster Size ( how many particles we want emitted within a certain area)
** Remember that unlike the PositionBorn operator, the Flow Emitter is more efficient in maintaining flow density or particles density over time/space, because every time a particle is away at a certain distance from emitter, another new particle is born. PositionBorn is not able to do this.**
-TimeInterval o/p to only Flow Emitter # 3 and 4 so the fluids will stream out only after a time interval from fluids # 1 and 2. In this scene FX, we want fluid stream 1 and 2 to flow out and collide first, followed by stream 3 and 4 to collide next.
– PositionBorn: create a field of particles with PistolShot. Thsi field will store the Open VDB volume grid.
** Cebas is the only market V/FX software that has uniquely integrated Open VDB in thinkingParticles that is particle-based so that every single particle can hold its own volume grid data. So, there is no entity that holds all the scene volume data (like most other applications). Particles can share the same name because the particles ID is the differentiator here. **
– Mix o/p Particle Age to Particle Die: set Die in Time: 120 frames (est. after the 100th particle) – make sure newly born particlesget the 120 frames die time/
FLOW OPERATOR – if off the ‘flow’ no physical fluid effects and the particles will not collide but as shown now, penetrate into each other. – activate the FlowGroup – FlowSolver turns the particles to a fluid system and create the authentic looking effects of fluid surface tension and droplets. – play scene – now you can see the fluid behavior at work.
OPEN VDB – to mix color and get an authentic color mixture and diffusion effects at collision. – Open VDB handles the name and type of volume grids and contains them for accessibility.
Initiator VDB – creates the volume grid (meaning fill data into volume grids) options here we use Source Open VDb – Grid PGrp: Color. – Weight : Build Average. By selecting this, Instruction is to grab the info from all named voxels and to average out the color info. – this causes the effects of color interpolation and diffusion. – Update to subsamples and re-evaluates with every new particles. – voxel size : define coarse/ refine. We set the initial Cell Mode to ‘None’ because there is no ‘container’ in the beginning so that volume is defined by the info we pull in later. – Initiator o/p color field to InputFromVDB / Mix PGrp: CH0: color (data channel created earlier for the particle group). – if no voxel / grid cells, the setup will auto-generate one for you so that is the beauty of using Open VDB. Parameter Voxel Edit: create non-existing – Scatte: extrapolate – GetNamedVDB o/p OutputToVDB:
GetNamedVDB – when particles places a color into the volume grid, we want to read it out for the next particle to take on the new color so that the color mixing over time will eventually include all the color mixture and values. – OutputToVDB: reverse of the input – places the color info after mixing back into the particles. – Transmission: control how color spreads into volume grid. Parameter Voxel Edit: Active only.
SHOW VDB – viewport set to ‘none’. PGroup: Field. Grid: color. – play scene : as we have Off the viewport and particles are invisible on ShowVDb what we see here is the Volume Grid. ** you can play with how fine you want the volume grid to be. But you cannot have a volume grid that is finer than the amount of particles as that won’t work. If you make the grid too fine, errors may occur as no captured particles at all. ** Likes: 0 Viewed: source
