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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 | # 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 Mesh
#
# Shows how to implement a PBD particle simulation with collision against
# a deforming triangle mesh. The mesh collision uses wp.mesh_query_point_sign_normal()
# to compute the closest point, and wp.Mesh.refit() to update the mesh
# object after deformation.
#
###########################################################################
import os
import numpy as np
from pxr import Usd, UsdGeom
import warp as wp
import warp.render
wp.init()
@wp.kernel
def deform(positions: wp.array(dtype=wp.vec3), t: float):
tid = wp.tid()
x = positions[tid]
offset = -wp.sin(x[0]) * 0.02
scale = wp.sin(t)
x = x + wp.vec3(0.0, offset * scale, 0.0)
positions[tid] = x
@wp.kernel
def simulate(
positions: wp.array(dtype=wp.vec3),
velocities: wp.array(dtype=wp.vec3),
mesh: wp.uint64,
margin: float,
dt: float,
):
tid = wp.tid()
x = positions[tid]
v = velocities[tid]
v = v + wp.vec3(0.0, 0.0 - 9.8, 0.0) * dt - v * 0.1 * dt
xpred = x + v * dt
face_index = int(0)
face_u = float(0.0)
face_v = float(0.0)
sign = float(0.0)
max_dist = 1.5
if wp.mesh_query_point_sign_normal(mesh, xpred, max_dist, sign, face_index, face_u, face_v):
p = wp.mesh_eval_position(mesh, face_index, face_u, face_v)
delta = xpred - p
dist = wp.length(delta) * sign
err = dist - margin
# mesh collision
if err < 0.0:
n = wp.normalize(delta) * sign
xpred = xpred - n * err
# 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 = 1000
self.sim_steps = 500
self.sim_dt = 1.0 / 60.0
self.sim_time = 0.0
self.sim_timers = {}
self.sim_margin = 0.1
self.renderer = wp.render.UsdRenderer(stage)
usd_stage = Usd.Stage.Open(os.path.join(os.path.dirname(__file__), "assets/bunny.usd"))
usd_geom = UsdGeom.Mesh(usd_stage.GetPrimAtPath("/bunny/bunny"))
usd_scale = 10.0
# create collision mesh
self.mesh = wp.Mesh(
points=wp.array(usd_geom.GetPointsAttr().Get() * usd_scale, dtype=wp.vec3),
indices=wp.array(usd_geom.GetFaceVertexIndicesAttr().Get(), dtype=int),
)
# random particles
init_pos = (np.random.rand(self.num_particles, 3) - np.array([0.5, -1.5, 0.5])) * 10.0
init_vel = np.random.rand(self.num_particles, 3) * 0.0
self.positions = wp.from_numpy(init_pos, dtype=wp.vec3)
self.velocities = wp.from_numpy(init_vel, dtype=wp.vec3)
def update(self):
with wp.ScopedTimer("simulate", detailed=False, dict=self.sim_timers):
wp.launch(kernel=deform, dim=len(self.mesh.points), inputs=[self.mesh.points, self.sim_time])
# refit the mesh BVH to account for the deformation
self.mesh.refit()
wp.launch(
kernel=simulate,
dim=self.num_particles,
inputs=[self.positions, self.velocities, self.mesh.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_mesh(name="mesh", points=self.mesh.points.numpy(), indices=self.mesh.indices.numpy())
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_mesh.usd")
example = Example(stage_path)
for i in range(example.sim_steps):
example.update()
example.render()
example.renderer.save()
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