Houdini AdventCalender Project 2018 Advanced Fluid Animation system

↓↓↓Basic  Animation System　Overview

https://drive.google.com/file/d/1jaMs7x90m6BdRUqMLE8LsUIm4V4s5vCD/view?usp=sharing

:Basic Lagrange Animation System

PointPositionに直接変化量を持たせて現行位置を更新する。

int main

{

   for (int i; iterate>= i; i++;)

  {

   vector Pos = currentPos;

   vector v = (velocity*TimeInterval)*i;

   //i = dt

   @P = Pos +v;

   }

}

:Basic Euler Animation System

voxelに変化量を持たせてそれらを参照し更新する。

int main

{

   for (int i; iterate>= i; i++;)

  {

   vector Pos = currentPos;

   vector v = (voxel_Velocity * TimeInterval)*i;

   //voxel_Velocity = Sampling current_VelocityData

   //i = dt

   @P = Pos +v;

   }

}

↓↓↓Volume Displacement Overview

https://drive.google.com/file/d/18KG7Tpwez0OFkM1u5Rl0odHoXVK04J26/view?usp=sharing

int main

{

   vector idxPos = dnesityPosition;

   vector directiornalVector = normalize(gradient(density))*(amount*lengthnormalize(gradient(density)));

   vector pushUp = idxPos + directiornalVector

 

   float density = voxelTrace_density(pushUp);

 

   return density;

}




↓↓↓CameraSpace Advection Overview

https://drive.google.com/file/d/1vn79Uk6NZ6PwiegtF2zp73bsTwW1T2xy/view?usp=sharing

int main

{

   vector Pos = dnesityPosition;

   vector advectvelocity = cross(getvoxelvelocity,CameraSpace_Turbulence) *(1/FPS)*Timestep;

   vector PositionSample_A =  advectvelocity+ Pos;

 

   vector PositionSample_B =(getvoxelvelocity(PositionSample_A) *(1/FPS)*Timestep;

 

   Pos +=  PositionSample_B;

 

   density = voxelTrace_density(Pos);

   return density;

}

↓↓↓Sample Hip File

https://drive.google.com/file/d/1DnFM3kuFgbU1zeHN5WOE1EPc_zRIrd92/view?usp=sharing