- Put these lines into a script:
[ColorUsageAttribute(true, true, -5, 5, -5, 5)]
public Color myColor;
- Attach the script to game object and click on the Color in the Inspector to open the Color Picker Window - Color Picker will be set for HDR and will have the alpha transparency slider as expected
- Change the ColorUsageAttribute in the script to [ColorUsageAttribute(false, true, -5, 5, -5, 5)]
- Go back to the Editor and click the Color field again to open the Color Picker (notice the alpha slider is still there even if it was set to false in the script)
- If wait long enough or you close the Color Picker window and open it again, the alpha slider will eventually be gone, but seems like whatever reloading is happening in the Editor takes a bit too long