So I was having a lot of fun starting a videogame project and learning panda3d. I loaded a free rigged tank model from a .glb file I found in sketchfab using the Actor class. It looked gorgeous. So I tried animating it.
I started with the turret and rotated it with setHpr until I found the correct axis. It was so easy so I tried spinning the wheels within their axis. Which is something I did first within blender in pose mode and had no issue. But no matter how I tried the wheels allways rotated from the root skeleton bone as seen in the next picture:
This code fragment initializes my model, the next fragment is where the issue occurs
class T72Target:
def __init__(self, render, pos, model_base, speed_multiplier=1.0):
self.width = 7.5
self.length = 4.0
self.height = 2.4
self.node = render.attachNewNode("T72_Target")
self.model = Actor(model_base)
self.model.reparentTo(self.node)
self.model.setHpr(0, 0, 0)
self.model.setZ(0)
self.model.setScale(.0095)
self.turret_bone = self.model.controlJoint(None, "modelRoot", "C_Turret")
self.barrel_bone = self.model.controlJoint(None, "modelRoot", "C_Gun")
self.c_node = CollisionNode('target_collision')
c_box = CollisionBox(Vec3(0, 0, self.height / 2), self.width / 2, self.length / 2, self.height / 2)
self.c_node.addSolid(c_box)
self.c_node.setIntoCollideMask(BitMask32.bit(1))
self.c_np = self.node.attachNewNode(self.c_node)
self.c_np.setPythonTag("target_object", self)
self.node.setPos(pos)
self.speed = random.choice([-15.0, -1.0, 1.0, 15.0]) * speed_multiplier
self.is_destroyed = False
#Here is where I seach the wheel bones, no issue yet
self.LT_Wheels = [self.model.controlJoint(None, "modelRoot", "L_Wheel_0{n}".format(n=i)) for i in range(1,8)]
self.RT_Wheels = [self.model.controlJoint(None, "modelRoot", "R_Wheel_0{n}".format(n=i)) for i in range(1,8)]
But when I try to rotate each individual wheel, no matter how many. They rotate along the root:
#These are the methods where the issue happened
def rotate_left_track(self, speed, dt):
instant_speed = speed * dt
#Here
for wheel in self.LT_Wheels:
wheel.setH(wheel.getH() + instant_speed)
def rotate_rigth_track(self, speed, dt):
instant_speed = speed * dt
#and here, no matter the axis, H P or R
for wheel in self.RT_Wheels:
wheel.setH(wheel.getH() + instant_speed)
#here are the rest
def rotate_turret(self, speed, dt):
r = self.turret_bone.get_r()
self.turret_bone.set_r(r+speed*dt)
def update(self, dt):
if self.is_destroyed:
return
current_pos = self.node.getPos()
current_pos.x += self.speed * dt
if abs(current_pos.x) > 400:
self.speed *= -1
self.node.setPos(current_pos)
self.rotate_turret( 15, dt)
#This is where the issue happens
self.rotate_left_track(self.speed , dt)
self.rotate_rigth_track(self.speed , dt)
def destroy(self):
self.is_destroyed = True
self.node.removeNode()
I don’t want to risk breaking the share your own stuff guideline so I won’t include the link to the model from sketchfab (Unless it’s ok ).
Here is the bone hierarchy:
CharacterJointBundle T72B_Model {
PartGroup <skeleton> {
LMatrix4f Skeleton {
LMatrix4f Root {
LMatrix4f C_Cog {
LMatrix4f C_Driver_Hatch
LMatrix4f C_Turret {
LMatrix4f C_Commander_Hatch
LMatrix4f C_Gun {
LMatrix4f C_Gun_01
}
LMatrix4f C_Hatch
}
LMatrix4f L_Wheel_01
LMatrix4f L_Wheel_09
LMatrix4f R_Wheel_01
LMatrix4f R_Wheel_09
}
LMatrix4f L_Wheel_02_Track {
LMatrix4f L_Wheel_02
}
LMatrix4f L_Wheel_03_Track {
LMatrix4f L_Wheel_03
}
LMatrix4f L_Wheel_04_Track {
LMatrix4f L_Wheel_04
}
LMatrix4f L_Wheel_05_Track {
LMatrix4f L_Wheel_05
}
LMatrix4f L_Wheel_06_Track {
LMatrix4f L_Wheel_06
}
LMatrix4f L_Wheel_07_Track {
LMatrix4f L_Wheel_07
}
LMatrix4f R_Wheel_02_Track {
LMatrix4f R_Wheel_02
}
LMatrix4f R_Wheel_03_Track {
LMatrix4f R_Wheel_03
}
LMatrix4f R_Wheel_04_Track {
LMatrix4f R_Wheel_04
}
LMatrix4f R_Wheel_05_Track {
LMatrix4f R_Wheel_05
}
LMatrix4f R_Wheel_06_Track {
LMatrix4f R_Wheel_06
}
LMatrix4f R_Wheel_07_Track {
LMatrix4f R_Wheel_07
}
}
}
}
PartGroup morph {
}
}
