Calling MeshDrawer segment and link_segment Crashes Panda3D

[Jonathan Kelly]

At least on Windows 7 and XP using Panda3D versions from 1.8.0 to 1.9.3, calling the segment() or link_segment() functions of MeshDrawer crashes Panda but offers the following fatal error:

:express(error): Attempt to cast pointer from ModelNode to Camera

Forum Topic: http://www.panda3d.org/forums/viewtopic.php?f=4&t=19307

Example Code:

from direct.showbase.ShowBase import ShowBase
from panda3d.core import MeshDrawer, NodePath

class Test(ShowBase):

    def __init__(self):
        ShowBase.__init__(self)
        self.drawer = MeshDrawer()
        self.drawer_node = self.drawer.get_root()
        self.drawer_node.reparent_to(render)
        self.drawer_node.set_two_sided(True)
        self.drawer_node.set_pos(0, 100, 0)
        self.drawer.set_budget(512)
        self.time = 0
        taskMgr.add(self.update_task, 'universe')

    def update_task(self, task):
        self.time += globalClock.get_dt()
        self.drawer.begin(camera, render)

        # Test that segment and link_segment do not fatally crash.
        # At least on Windows 7 and XP it crashes with the following error -
        # :express(error): Attempt to cast pointer from ModelNode to Camera
        self.drawer.segment((0, 0, 10), (1, 10, 1), (0, 0, 1, 1), 1,
                            (1, 1, 0, 1))

        self.drawer.end()
        return task.cont

test = Test()
test.run()

[rdb (rdb)]

I think it expects you to pass base.cam instead of camera. Does that resolve the crash?

[rdb (rdb)]

The fix is to pass base.cam to the begin() call. I have, however, replaced the crash with an exception instead.

[Jonathan Kelly (self.deus)]

Yes indeed, using base.cam fixes the issue for me as well. I should have followed the example in the manual more closely it seems.

Also, sorry for the late reply, I missed the notification until just now.