To use Kudan's Unity Plugin in the editor, an Editor API Key is required. To get one, you can click the button labelled "Get Editor API Key" at the bottom of the
Kudan Tracker script on the
Kudan Camera object, or you can simply follow this link.
You'll have to register an account with Kudan to continue, but once you do, you can claim your free editor key to use in as many projects as you like.
To use this key, go back to your Unity project and select the
Kudan Camera object. In the
Kudan Tracker script is a box labelled "Editor API Key". Copy the key you generated and paste it in this box.
When you run the scene in Play Mode, some messages will print out to the console. If you have followed the above step correctly, you should see the message "[KudanAR] Editor Play Mode Key is Valid". If you have not, it will instead display an error with the message "[KudanAR] Editor Play Mode Key is NOT Valid."
If you have a built-in webcam, this step isn't necessary, and you should be able to start Play Mode. If you're planning to use a USB webcam, however, you should continue reading.
Kudan Tracker script also has a slider labelled "Play Mode Webcam ID". This is the camera that will be used when the app starts. Usually, when a USB webcam is plugged in, the computer sets it to have an ID of 0, as it generally prioritises something plugged in over something built-in. If you were to plug in a USB camera and use that, then leaving the Webcam ID at "Zero" should be fine.
However, if you change the USB port the camera is plugged into, or if you have multiple USB cameras and wish to use a specific one, or even if you have a USB webcam plugged in but want to try out a built-in webcam, you will need to check through the different IDs.
Sometimes a camera can be assigned a strange ID based on the USB port it has been plugged into, so be sure to check all of them if it doesn't work right away.