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import math
import numpy as np
import dartpy as dart
class MyWorldNode(dart.gui.osg.RealTimeWorldNode):
def __init__(self, world, chain):
super(MyWorldNode, self).__init__(world)
self.chain = chain
def customPreStep(self):
pass
def main():
world = dart.utils.SkelParser.readWorld('dart://sample/skel/chain.skel');
world.setGravity([0, -9.81, 0])
world.setTimeStep(1.0/2000)
chain = world.getSkeleton(0)
for i in range(chain.getNumJoints()):
joint = chain.getJoint(i)
for j in range(joint.getNumDofs()):
joint.setDampingCoefficient(j, 0.01)
dof = chain.getNumDofs()
init_pose = np.zeros(dof)
init_pose[20] = math.pi * 0.4
init_pose[23] = math.pi * 0.4
init_pose[26] = math.pi * 0.4
init_pose[29] = math.pi * 0.4
chain.setPositions(init_pose)
# Create a ball joint contraint
bd1 = chain.getBodyNode('link 6')
bd2 = chain.getBodyNode('link 10')
shape_node1 = bd1.getShapeNode(0)
shape_node2 = bd2.getShapeNode(0)
visual1 = shape_node1.getVisualAspect()
visual2 = shape_node2.getVisualAspect()
visual1.setColor([1, 0, 0])
visual2.setColor([1, 0, 0])
offset = [0, 0.025, 0]
joint_pos = bd1.getTransform().multiply(offset)
constraint = dart.constraint.BallJointConstraint(bd1, bd2, joint_pos)
constraint_solver = world.getConstraintSolver()
constraint_solver.addConstraint(constraint)
node = MyWorldNode(world, chain)
# Create world node and add it to viewer
viewer = dart.gui.osg.Viewer()
viewer.addWorldNode(node)
# Grid settings
grid = dart.gui.osg.GridVisual()
grid.setPlaneType(dart.gui.osg.GridVisual.PlaneType.ZX)
grid.setOffset([0, -0.55, 0])
viewer.addAttachment(grid)
viewer.setUpViewInWindow(0, 0, 640, 480)
viewer.setCameraHomePosition([0.6, 0.3, 0.6], [0, -0.2, 0], [0, 1, 0])
viewer.run()
if __name__ == "__main__":
main()
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