Spaces:
Sleeping
Sleeping
File size: 5,165 Bytes
66c9c8a | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 | # Copyright (c) 2022 NVIDIA CORPORATION. All rights reserved.
# NVIDIA CORPORATION and its licensors retain all intellectual property
# and proprietary rights in and to this software, related documentation
# and any modifications thereto. Any use, reproduction, disclosure or
# distribution of this software and related documentation without an express
# license agreement from NVIDIA CORPORATION is strictly prohibited.
###########################################################################
# Example NanoVDB
#
# Shows how to implement a particle simulation with collision against
# a NanoVDB signed-distance field. In this example the NanoVDB field
# is created offline in Houdini. The particle kernel uses the Warp
# wp.volume_sample_f() method to compute the SDF and normal at a point.
#
###########################################################################
import math
import os
import numpy as np
import warp as wp
import warp.render
wp.init()
@wp.func
def volume_grad(volume: wp.uint64, p: wp.vec3):
eps = 1.0
q = wp.volume_world_to_index(volume, p)
# compute gradient of the SDF using finite differences
dx = wp.volume_sample_f(volume, q + wp.vec3(eps, 0.0, 0.0), wp.Volume.LINEAR) - wp.volume_sample_f(
volume, q - wp.vec3(eps, 0.0, 0.0), wp.Volume.LINEAR
)
dy = wp.volume_sample_f(volume, q + wp.vec3(0.0, eps, 0.0), wp.Volume.LINEAR) - wp.volume_sample_f(
volume, q - wp.vec3(0.0, eps, 0.0), wp.Volume.LINEAR
)
dz = wp.volume_sample_f(volume, q + wp.vec3(0.0, 0.0, eps), wp.Volume.LINEAR) - wp.volume_sample_f(
volume, q - wp.vec3(0.0, 0.0, eps), wp.Volume.LINEAR
)
return wp.normalize(wp.vec3(dx, dy, dz))
@wp.kernel
def simulate(
positions: wp.array(dtype=wp.vec3),
velocities: wp.array(dtype=wp.vec3),
volume: wp.uint64,
margin: float,
dt: float,
):
tid = wp.tid()
x = positions[tid]
v = velocities[tid]
v = v + wp.vec3(0.0, 0.0, -980.0) * dt - v * 0.1 * dt
xpred = x + v * dt
xpred_local = wp.volume_world_to_index(volume, xpred)
# d = wp.volume_sample_f(volume, xpred_local, wp.Volume.LINEAR)
n = wp.vec3()
d = wp.volume_sample_grad_f(volume, xpred_local, wp.Volume.LINEAR, n)
if d < margin:
# n = volume_grad(volume, xpred)
n = wp.normalize(n)
err = d - margin
# mesh collision
xpred = xpred - n * err
# ground collision
if xpred[2] < 0.0:
xpred = wp.vec3(xpred[0], xpred[1], 0.0)
# pbd update
v = (xpred - x) * (1.0 / dt)
x = xpred
positions[tid] = x
velocities[tid] = v
class Example:
def __init__(self, stage):
self.num_particles = 10000
self.sim_steps = 1000
frame_dt = 1.0 / 60.0
self.sim_substeps = 3
self.sim_dt = frame_dt / self.sim_substeps
self.sim_time = 0.0
self.sim_timers = {}
self.sim_render = True
self.sim_margin = 15.0
self.renderer = wp.render.UsdRenderer(stage, up_axis="z")
self.renderer.render_ground(size=10000.0)
init_pos = 1000.0 * (np.random.rand(self.num_particles, 3) * 2.0 - 1.0) + np.array((0.0, 0.0, 3000.0))
init_vel = np.random.rand(self.num_particles, 3)
self.positions = wp.from_numpy(init_pos.astype(np.float32), dtype=wp.vec3)
self.velocities = wp.from_numpy(init_vel.astype(np.float32), dtype=wp.vec3)
# load collision volume
file = open(os.path.join(os.path.dirname(__file__), "assets/rocks.nvdb"), "rb")
# create Volume object
self.volume = wp.Volume.load_from_nvdb(file)
file.close()
def update(self):
with wp.ScopedTimer("simulate", detailed=False, dict=self.sim_timers):
for _ in range(self.sim_substeps):
wp.launch(
kernel=simulate,
dim=self.num_particles,
inputs=[
self.positions,
self.velocities,
self.volume.id,
self.sim_margin,
self.sim_dt,
],
)
self.sim_time += self.sim_dt
def render(self, is_live=False):
with wp.ScopedTimer("render", detailed=False):
time = 0.0 if is_live else self.sim_time
self.renderer.begin_frame(time)
self.renderer.render_ref(
name="collision",
path=os.path.join(os.path.dirname(__file__), "assets/rocks.usd"),
pos=wp.vec3(0.0, 0.0, 0.0),
rot=wp.quat_from_axis_angle(wp.vec3(1.0, 0.0, 0.0), math.pi),
scale=wp.vec3(1.0, 1.0, 1.0),
)
self.renderer.render_points(name="points", points=self.positions.numpy(), radius=self.sim_margin)
self.renderer.end_frame()
if __name__ == "__main__":
stage_path = os.path.join(os.path.dirname(__file__), "outputs/example_nvdb.usd")
example = Example(stage_path)
for i in range(example.sim_steps):
example.update()
example.render()
example.renderer.save()
|