System Information
Window 7 home premium SP1
AMD REDEON HD 7670M
System Information
Window 7 home premium SP1
AMD REDEON HD 7670M
Blender Version
Broken: 2.76b f337fea
Worked: (optional)
Short description of error
A Rigid Body (RB) with the following fcurves:
- animated checkbox enabled from frame 0 to frame F-1 and from frame F with the animated checkbox disabled,
- locationX keyframed in order to give a velocity to the RB (eg. constant slope from frame 0 to frame 250)
does not keep its initial velocity after the frame F.
The velocity assumed by the RB depends on if the F is even or odd, the speed and the steps per second of the simulation.
When the the rigid body parameters (in the scene tab) "speed" and "steps per second" are 1.0 and 60.0 (default):
if the frame F is even the RB is faster, if the frame F is odd the RB is slower then the initial velocity.
With "speed" 2.0, 4.0 the RB seems to keep the initial velocity.
With "speed" 3.0, 5.0 the differences appear again.
Increasing the "steps per second" reduces the differece, but it is still appreciable.
Exact steps for others to reproduce the error
6 Rigid Bodies (Cubes) with dynamic and animated checkbox enabled from frame 0 and from frame F the checkbox animated is disabled. The "LocationX" is also keyframed in order to have a velocity when the animated checkbox is disabled.
To semplify and make more evident the effects, the f-curve is at constant slope (type of handle vector; keyframe=0 X=0, keyframe=250 X=25). Furthermore, the gravity is disabled and the "translation damping" is set to 0.0.
To check the velocity there is another Rigid Body that can be taken as reference, with the same f-curve for locationX, but with the animated checkbox kept enabled.
The details are in the following script
import bpy
# delete the the cube in the start-up file
bpy.ops.object.delete(use_global=False)
# add 7 cubes along the y axis
for Y in [-9,-6,-3,0,3,6,9]:
bpy.ops.mesh.primitive_cube_add(radius=1.0, location=(0,Y,0))
# define a material
matOcra=bpy.data.materials.new('Ocra')
matOcra.diffuse_color=((0.8,0.3,0.02))
# add to each cube a fcurve of constant slope 0.1 units per frame
# from frame 0 to frame 250
bpy.context.scene.frame_start = 0
bpy.context.scene.frame_current = 0
for obj in bpy.data.objects:
if obj.type=="MESH":
# add a fcurve of constant slope (0.1 units per frame)
# from frame 0 to frame 250 to each cube
obj.location[0] = 0.0
obj.keyframe_insert(data_path="location", frame=0.0, index=0)
obj.location[0] = 25.0
obj.keyframe_insert(data_path="location", frame=250.0, index=0)
obj.animation_data.action.fcurves[0].keyframe_points[0].handle_left_type='VECTOR'
obj.animation_data.action.fcurves[0].keyframe_points[0].handle_right_type='VECTOR'
obj.animation_data.action.fcurves[0].keyframe_points[1].handle_left_type='VECTOR'
obj.animation_data.action.fcurves[0].keyframe_points[1].handle_right_type='VECTOR'
obj.animation_data.action.fcurves[0].update()
bpy.context.scene.objects.active=obj
bpy.ops.rigidbody.object_add(type='ACTIVE')
obj.rigid_body.linear_damping=0.0
obj.rigid_body.angular_damping=0.0
obj.rigid_body.kinematic=True
obj.keyframe_insert(data_path="rigid_body.kinematic", frame=0.0, index=-1)
Y=obj.location.y
if Y!=0:
obj.rigid_body.kinematic=False
if Y>0:
F=19+Y/3
else:
F=20+Y/3
obj.keyframe_insert(data_path="rigid_body.kinematic", frame=F, index=-1)
bpy.ops.object.text_add(enter_editmode=True,location=(2,Y,-1))
bpy.ops.font.delete()
bpy.ops.font.text_insert(text="Animation checkbox disabled at frame "+str(F))
else:
obj.data.materials.append(matOcra)
bpy.ops.object.text_add(enter_editmode=True,location=(2,Y,-1))
bpy.ops.font.delete()
bpy.ops.font.text_insert(text="Reference - animation checkbox always enabled")
bpy.ops.object.editmode_toggle()
obj_txt=bpy.context.scene.objects.active
obj_txt.data.materials.append(matOcra)
bpy.context.scene.use_gravity = FalsePlease see also the attached .blend file