What can cause an Assertion Error while running in Ursina?

Question

I'm pretty new to programming with Python and am starting to learn how to use Ursina Game Engine...

Currently I'm running Python 3.9.4 through IDLE. I looked up a YouTube playlist that goes through different activities using Ursina. However I hit a snag with one of the videos. I keep receiving an Assertion Error even though I copied the code exactly as it is shown in the video.

Here is the complete Error I'm receiving:

= RESTART: C:/Users/Charbel/Desktop/Ursina Tutorials/smooth follow - flying dragon.py
package_folder: C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\ursina
asset_folder: C:\Users\Charbel\Desktop\Ursina Tutorials
blender_paths:
{'2.7': WindowsPath('C:/Program Files/Blender Foundation/Blender/blender.exe'),
 '2.8': WindowsPath('C:/Program Files/Blender Foundation/Blender 2.83/blender.exe'),
 'default': WindowsPath('C:/Program Files/Blender Foundation/Blender 2.83/blender.exe')}
screen resolution: (1366, 768)
size; LVector2f(1092, 614)
render mode: default
development mode: True
application successfully started
Traceback (most recent call last):
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\direct\showbase\ShowBase.py", line 2153, in __igLoop
    self.graphicsEngine.renderFrame()
AssertionError: !mat.is_nan() at line 322 of c:\buildslave\sdk-windows-amd64\build\panda\src\pgraph\transformState.cxx
Traceback (most recent call last):
  File "C:/Users/Charbel/Desktop/Ursina Tutorials/smooth follow - flying dragon.py", line 22, in <module>
    app.run()
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\ursina\main.py", line 238, in run
    super().run()
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\direct\showbase\ShowBase.py", line 3325, in run
    self.taskMgr.run()
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\direct\task\Task.py", line 546, in run
    self.step()
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\direct\task\Task.py", line 500, in step
    self.mgr.poll()
  File "C:\Users\Charbel\AppData\Roaming\Python\Python39\site-packages\direct\showbase\ShowBase.py", line 2153, in __igLoop
    self.graphicsEngine.renderFrame()
AssertionError: !mat.is_nan() at line 322 of c:\buildslave\sdk-windows-amd64\build\panda\src\pgraph\transformState.cxx

Here's a copy of my entire code:

from ursina import *

def update():
    global dy
    player.y += dy

    if abs(player.y)>= 3:
        dy = -dy
        
app = Ursina()

player = Entity(model='quad', scale=1, x = -4.5, texture = 'dragon_head.png')
e = [None]*50

e[0] = Entity(model='circle', scale = .2, color = color.green)
e[0].add_script(SmoothFollow(target = player, offset=(.3, 0, 0)))
dy =.08
for i in range(1,50):
    e[i] = Entity(model='circle', scale = .2, color = color.green)
    e[i].add_script(SmoothFollow(target = e[i-1], offset=(.2, 0, 0)))

app.run()

It appears that the error has something to do with the e[i-1] from my investigation. Has anyone else run into a similar issue or know if there's a bug in the Ursina language that causes this?

Thanks in advance

Charbel

Very strange. If I reduce the number of followers from 50 to 34, it works. If I increase it to 35, it starts breaking - but inconsistently when running repeatedly. It also works when I comment out the `e[i].add_script` line, execute it, uncomment the line and refresh the code with F5. This reeks of some invalid memory initialization in Panda3D, the underlying engine Ursina uses. — Jan Wilamowski, Sep 24 '21 at 03:42
I know... it is very strange. I don't know why specifically that line is causing an issue. if I remove the for loop and insert each object of the list individually (i.e... e[0] to e[50]), it works. There is something specifically wrong with that line and it doesn't make sense. — Charbel Massoud, Sep 25 '21 at 23:00

score 1 · Answer 1 · answered Jun 14 '22 at 02:38

1

My app just run to this error either.I think it is a rendering error caused by insufficient GPU computing power of the graphics.I reduce it to 44 and it works.

answered Jun 14 '22 at 02:38

Vaughan

11
1

score 1 · Answer 2 · answered Nov 09 '22 at 14:31

I'd assume either your computer or engine cannot handle it. I tried making a cube's rotation_z multiplied by an absurdly large number (100000000000000000000000000000000000000 to be exact) and it ran fine, but when I added an extra zero to the number, the engine broke.

What can cause an Assertion Error while running in Ursina?

2 Answers2