def test_newtons_first_law_motion():
# When no external force acts, a body with constant velocity
# continues to move with that velocity.
cube_verts = torch.FloatTensor(
[
[1.0, 1.0, 1.0],
[1.0, -1.0, 1.0],
[1.0, -1.0, -1.0],
[1.0, 1.0, -1.0],
[-1.0, 1.0, 1.0],
[-1.0, -1.0, 1.0],
[-1.0, -1.0, -1.0],
[-1.0, 1.0, -1.0],
]
)
cube = RigidBody(cube_verts)
# Give the cube a linear momentum of `(8, 8, 8)` (it's mass is `8`),
# so, the velocity becomes `1` meter per second. Our frame rate by
# default, is 30 Hz, i.e., 0.033 meters per frame.
cube.linear_momentum = torch.ones(3, dtype=torch.float32) * 8
sim = Simulator([cube])
sim.step()
assert torch.allclose(cube.position, 0.0333 * torch.ones(3), atol=1e-4)
sim.step()
assert torch.allclose(cube.position, 0.0667 * torch.ones(3), atol=1e-4)
sim.step()
assert torch.allclose(cube.position, 0.1 * torch.ones(3), atol=1e-4)
def test_cube_with_gravity():
# Add gravity to the cube.
cube_verts = torch.FloatTensor(
[
[1.0, 1.0, 1.0],
[1.0, -1.0, 1.0],
[1.0, -1.0, -1.0],
[1.0, 1.0, -1.0],
[-1.0, 1.0, 1.0],
[-1.0, -1.0, 1.0],
[-1.0, -1.0, -1.0],
[-1.0, 1.0, -1.0],
]
)
cube = RigidBody(cube_verts)
gravity = Gravity()
direction = torch.tensor([0.0, 0.0, -1.0])
cube.add_external_force(gravity)
sim = Simulator([cube])
sim.step()
assert torch.allclose(cube.linear_velocity, 0.3333333 * direction)
assert torch.allclose(cube.position, 0.0111111 * direction)
sim.step()
assert torch.allclose(cube.linear_velocity, 0.66666667 * direction)
assert torch.allclose(cube.position, 0.0333333 * direction)
sim.step()
assert torch.allclose(cube.linear_velocity, 1.0 * direction)
assert torch.allclose(cube.position, 0.0666667 * direction)
def test_create_body():
cube_verts = torch.FloatTensor([
[1.0, 1.0, 1.0],
[1.0, -1.0, 1.0],
[1.0, -1.0, -1.0],
[1.0, 1.0, -1.0],
[-1.0, 1.0, 1.0],
[-1.0, -1.0, 1.0],
[-1.0, -1.0, -1.0],
[-1.0, 1.0, -1.0],
])
cube = RigidBody(cube_verts)
def make_rigid_body(sample,
init_pos,
orientation,
linear_velocity,
angular_velocity,
device,
target_vertices=None):
# Load a triangle mesh obj file
if target_vertices is not None:
tmp_obj_file = '/tmp/obj.obj'
from blender_process import Process
p = Process(sample.obj, target_vertices, tmp_obj_file)
mesh = TriangleMesh.from_obj(tmp_obj_file)
else:
mesh = TriangleMesh.from_obj(sample.obj)
vertices = (meshutils.normalize_vertices(
mesh.vertices).unsqueeze(0).to(device))
faces = mesh.faces.unsqueeze(0).to(device)
textures = torch.cat(
(
sample.color[0] / 255 * torch.ones(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
sample.color[1] / 255 * torch.ones(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
sample.color[2] / 255 * torch.ones(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
),
dim=-1,
)
# (Uniform) Masses
masses = (sample.mass / vertices.shape[-2]) * torch.nn.Parameter(
torch.ones(vertices.shape[-2], dtype=vertices.dtype, device=device),
requires_grad=True,
)
# Body
body = RigidBody(
vertices[0],
position=torch.tensor(init_pos, dtype=torch.float32, device=device),
masses=masses,
orientation=torch.tensor(orientation).type(torch.float32).to(device),
friction_coefficient=sample.fric,
# linear_velocity=torch.tensor(linear_velocity).type(torch.float32).to(device)
# angular_veloctiy=torch.tensor(angular_velocity).type(torch.float32).to(device)
)
return body, vertices, faces, textures
def test_newtons_first_law_rest():
# When no external force acts, bodies at rest remain at rest.
cube_verts = torch.FloatTensor(
[
[1.0, 1.0, 1.0],
[1.0, -1.0, 1.0],
[1.0, -1.0, -1.0],
[1.0, 1.0, -1.0],
[-1.0, 1.0, 1.0],
[-1.0, -1.0, 1.0],
[-1.0, -1.0, -1.0],
[-1.0, 1.0, -1.0],
]
)
cube = RigidBody(cube_verts)
sim = Simulator([cube])
sim.step()
assert torch.allclose(cube.position, torch.zeros(3))
sim.step()
assert torch.allclose(cube.position, torch.zeros(3))
# print("GT mass:", mass[0], mass[0] * vertices.shape[-2])
true_masses.append(mass[0])
# (Uniform) Masses
masses_gt = (float(mass[0])) * torch.nn.Parameter(
torch.ones(vertices.shape[-2], dtype=vertices.dtype,
device=device),
requires_grad=True,
)
# Body
body_gt = RigidBody(
vertices[0],
masses=masses_gt,
# position=torch.from_numpy(init_pos[i]).float().to(device),
orientation=torch.from_numpy(orientation[0]).float().to(device),
friction_coefficient=float(fric[0]),
restitution=float(elas[0]),
# linear_velocity=torch.tensor(linear_velocity[i], device=device),
# angular_velocity=torch.tensor(angular_velocity[i], device=device),
)
# inds = body_gt.vertices.argmin(1)
# application_points = list(inds.view(-1).detach().cpu().numpy())
# print("Est app points:", application_points)
application_points = [force_application_points[0]]
# print("True app points:", application_points)
# Add a force
force = ConstantForce(
magnitude=force_magnitude[0],
direction=torch.from_numpy(force_direction[0]).float().to(device),
starttime=0.0,
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.zeros(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
),
dim=-1,
)
masses = torch.nn.Parameter(
0.1 * torch.ones(vertices.shape[1], dtype=vertices.dtype, device=device),
requires_grad=True,
)
position = torch.tensor([0.0, 4.0, 0.0], dtype=torch.float32, device=device)
orientation = torch.tensor([1.0, 0.0, 0.0, 0.0], dtype=torch.float32, device=device)
body = RigidBody(
vertices[0],
position=position,
orientation=orientation,
masses=masses,
restitution=0.5,
)
# Create a force that applies gravity (g = 10 metres / second^2).
# gravity = Gravity(device=device)
force_magnitude = 10.0 # / vertices.shape[-2]
gravity = ConstantForce(
magnitude=force_magnitude,
direction=torch.tensor([0.0, -1.0, 0.0]),
device=device,
)
# Add this force to the body.
body.add_external_force(gravity)
if __name__ == "__main__":
cube_verts = torch.FloatTensor([
[1.0, 1.0, 1.0],
[1.0, -1.0, 1.0],
[1.0, -1.0, -1.0],
[1.0, 1.0, -1.0],
[-1.0, 1.0, 1.0],
[-1.0, -1.0, 1.0],
[-1.0, -1.0, -1.0],
[-1.0, 1.0, -1.0],
])
position = torch.tensor([2.0, 2.0, 2.0])
orientation = torch.tensor([1.0, 0.0, 0.0, 0.0])
cube = RigidBody(cube_verts + 1,
position=position,
orientation=orientation)
force_magnitude = 10.0 # / cube_verts.shape[0]
force_direction = torch.tensor([0.0, -1.0, 0.0])
gravity = ConstantForce(magnitude=force_magnitude,
direction=force_direction)
cube.add_external_force(gravity)
# sim = Simulator([cube], engine=EulerIntegratorWithContacts())
sim_substeps = 32
dtime = (1 / 30) / sim_substeps
sim = Simulator([cube],
engine=SemiImplicitEulerWithContacts(),
dtime=dtime)
(
torch.ones(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.ones(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.zeros(
1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
),
dim=-1,
)
masses = torch.nn.Parameter(
0.1 *
torch.ones(vertices.shape[1], dtype=vertices.dtype, device=device),
requires_grad=True,
)
body = RigidBody(vertices[0], masses=masses)
# Create a force that applies gravity (g = 10 metres / second^2).
# gravity = Gravity(device=device)
gravity = ConstantForce(direction=torch.tensor([0.0, -1.0, 0.0]),
device=device)
# Add this force to the body.
body.add_external_force(gravity, application_points=[0, 1])
# Initialize the simulator with the body at the origin.
sim = Simulator([body])
# Initialize the renderer.
renderer = SoftRenderer(camera_mode="look_at", device=device)
camera_distance = 8.0
# (Uniform) Masses
masses_gt = (float(mass[0])) * torch.nn.Parameter(
torch.ones(vertices.shape[-2], dtype=vertices.dtype,
device=device),
requires_grad=True,
)
restitution_gt = torch.nn.Parameter(
torch.tensor([float(elas[0])], dtype=vertices.dtype,
device=device), )
# Body
body_gt = RigidBody(
vertices[0],
masses=masses_gt,
position=torch.from_numpy(init_pos[0]).float().to(device),
orientation=torch.from_numpy(orientation[0]).float().to(device),
friction_coefficient=float(fric[0]),
restitution=restitution_gt,
# linear_velocity=torch.tensor(linear_velocity[i], device=device),
# angular_velocity=torch.tensor(angular_velocity[i], device=device),
)
# application_points = [force_application_points[0]]
# # Add a force
# force = ConstantForce(
# magnitude=force_magnitude[0],
# direction=torch.from_numpy(force_direction[0]).float().to(device),
# starttime=0.0,
# endtime=0.1,
# device=device,
# )
# body_gt.add_external_force(force, application_points=application_points)
(
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.zeros(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
),
dim=-1,
)
# masses_gt = torch.nn.Parameter(
# 1 * torch.ones(vertices.shape[1], dtype=vertices.dtype, device=device),
# requires_grad=False,
# )
masses_gt = torch.nn.Parameter(
torch.ones(vertices.shape[1], dtype=vertices.dtype, device=device),
requires_grad=False,
)
body_gt = RigidBody(vertices[0], masses=masses_gt)
# Create a force that applies gravity (g = 10 metres / second^2).
gravity = ConstantForce(
direction=torch.tensor([0.0, -1.0, 0.0]),
magnitude=args.force_magnitude,
device=device,
)
# Add this force to the body.
body_gt.add_external_force(gravity, application_points=[0, 1])
# Initialize the simulator with the body at the origin.
sim_gt = Simulator([body_gt])
# Initialize the renderer.
)
masses_gt = torch.nn.Parameter(
torch.ones(vertices.shape[1], dtype=vertices.dtype, device=device),
requires_grad=True,
)
position = torch.tensor([0.0, 4.0, 0.0],
dtype=torch.float32,
device=device)
orientation = torch.tensor([1.0, 0.0, 0.0, 0.0],
dtype=torch.float32,
device=device)
restitution_gt = 0.8
body = RigidBody(
vertices[0],
position=position,
orientation=orientation,
masses=masses_gt,
restitution=restitution_gt,
)
# Create a force that applies gravity (g = 10 metres / second^2).
# gravity = Gravity(device=device)
force_magnitude = 10.0 # / vertices.shape[-2]
gravity = ConstantForce(
magnitude=force_magnitude,
direction=torch.tensor([0.0, -1.0, 0.0]),
device=device,
)
# Add this force to the body.
body.add_external_force(gravity)
dtype=torch.float32,
device=device)
orientation_gt = torch.tensor([1.0, 0.0, 0.0, 0.0],
dtype=torch.float32,
device=device)
# mass_per_vertex = 1.0 / vertices_gt.shape[1]
mass_per_vertex = 1.0
masses_gt = torch.nn.Parameter(
mass_per_vertex * torch.ones(
vertices_gt.shape[1], dtype=vertices_gt.dtype, device=device),
requires_grad=False,
)
body_gt = RigidBody(
vertices_gt[0],
masses=masses_gt,
position=position_gt,
orientation=orientation_gt,
)
# Create a force that applies gravity (g = 10 metres / second^2).
# normalized_magnitude_gt = args.force_magnitude / vertices_gt.shape[-2]
gravity_gt = ConstantForce(
direction=torch.tensor([0.0, -1.0, 0.0]),
magnitude=args.force_magnitude,
device=device,
)
# Add this force to the body.
inds = vertices_gt.argmin(-2)[0]
application_points = list(inds.view(-1).detach().cpu().numpy())
body_gt.add_external_force(gravity_gt,
# Output (gif) file path
outfile = cache / "hellogradsim.gif"
# Load a body (from a triangle mesh obj file).
mesh = TriangleMesh.from_obj(Path("sampledata/banana.obj"))
vertices = meshutils.normalize_vertices(mesh.vertices.unsqueeze(0)).to(device)
faces = mesh.faces.to(device).unsqueeze(0)
textures = torch.cat(
(
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.ones(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
torch.zeros(1, faces.shape[1], 2, 1, dtype=torch.float32, device=device),
),
dim=-1,
)
body = RigidBody(vertices[0])
# Create a force that applies gravity (g = 10 metres / second^2).
# gravity = Gravity(device=device)
gravity = ConstantForce(direction=torch.tensor([0.0, -1.0, 0.0]), device=device)
# Add this force to the body.
body.add_external_force(gravity)
# Initialize the simulator with the body at the origin.
sim = Simulator([body])
# Initialize the renderer.
renderer = SoftRenderer(camera_mode="look_at", device=device)
camera_distance = 8.0
elevation = 30.0