[doc,demos] Update FLIP demos

tum-pbs · Dec 9, 2023 · 74b9238 · 74b9238
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Showing 2 changed files with 6 additions and 7 deletions.
diff --git a/demos/flip_liquid.py b/demos/flip_liquid.py
@@ -12,21 +12,20 @@
 
 
 domain = Box(x=64, y=64)
-gravity = vec(x=0, y=-9.81)
 obstacle = Box(x=(1, 25), y=(30, 33)).rotated(-20)
 particles = distribute_points(union(Box(x=(15, 30), y=(50, 60)), Box(x=None, y=(-INF, 5))), x=64, y=64) * (0, 0)
 
 
 @jit_compile
-def step(particles: Field, dt=.2):
+def step(particles: Field, pressure=None, dt=.1, gravity=vec(x=0, y=-9.81)):
     # --- Grid Operations ---
-    grid_v = prev_grid_v = field.finite_fill(resample(particles, StaggeredGrid(0, 0, x=64, y=64), scatter=True, outside_handling='clamp'))
+    grid_v = prev_grid_v = field.finite_fill(particles.at(StaggeredGrid(0, 0, domain, x=64, y=64), scatter=True, outside_handling='clamp'))
     occupied = resample(field.mask(particles), CenteredGrid(0, grid_v.extrapolation.spatial_gradient(), grid_v.bounds, grid_v.resolution), scatter=True, outside_handling='clamp')
     grid_v, pressure = fluid.make_incompressible(grid_v + gravity * dt, [obstacle], active=occupied)
     # --- Particle Operations ---
     particles += resample(grid_v - prev_grid_v, to=particles)  # FLIP update
     # particles = resample(grid_v, particles)  # PIC update
-    particles = advect.points(particles, grid_v * mask(~obstacle), dt, advect.finite_rk4)
+    particles = advect.points(particles, grid_v * resample(~obstacle, to=grid_v), dt, advect.finite_rk4)
     particles = fluid.boundary_push(particles, [obstacle, ~domain], separation=.5)
     return particles, pressure
 

diff --git a/docs/FLIP.ipynb b/docs/FLIP.ipynb
@@ -105,15 +105,15 @@
    "outputs": [],
    "source": [
     "@jit_compile\n",
-    "def step(particles: Field, pressure=None, dt=.2, gravity=vec(x=0, y=-9.81)):\n",
+    "def step(particles: Field, pressure=None, dt=.1, gravity=vec(x=0, y=-9.81)):\n",
     "    # --- Grid Operations ---\n",
-    "    grid_v = prev_grid_v = field.finite_fill(resample(particles, StaggeredGrid(0, 0, x=64, y=64), scatter=True, outside_handling='clamp'))\n",
+    "    grid_v = prev_grid_v = field.finite_fill(particles.at(StaggeredGrid(0, ZERO_GRADIENT, domain, x=64, y=64), scatter=True, outside_handling='clamp'))\n",
     "    occupied = resample(field.mask(particles), CenteredGrid(0, grid_v.extrapolation.spatial_gradient(), grid_v.bounds, grid_v.resolution), scatter=True, outside_handling='clamp')\n",
     "    grid_v, pressure = fluid.make_incompressible(grid_v + gravity * dt, [ground], active=occupied)\n",
     "    # --- Particle Operations ---\n",
     "    particles += resample(grid_v - prev_grid_v, to=particles)  # FLIP update\n",
     "    # particles = resample(grid_v, particles)  # PIC update\n",
-    "    particles = advect.points(particles, grid_v * mask(~ground), dt, advect.finite_rk4)\n",
+    "    particles = advect.points(particles, grid_v * resample(~ground, to=grid_v), dt, advect.finite_rk4)\n",
     "    particles = fluid.boundary_push(particles, [ground, ~domain], separation=.5)\n",
     "    return particles, pressure"
    ],