If the following error occurs, hardware acceleration may be disabled.
Please enable hardware acceleration with your browser.
Cannot read property ‘VERTEX_SHADER’ of undefined
It does not fix even if hardware acceleration is enabled
If your use Google Chrome, you may fix the problem by making special settings.
Please enter the following url in the address bar and open the setting.
Please press "Enable" in the item with yellow highlight (Override software rendering list).
A dialog will ask you to restart, so restart Google Chrome.