The Question layer is used to set up conditions which, if passed, will trigger actions.
The first step is to assign what kind of question will be asked using the options: If (the default), Else If or Else.
The starting question of any hierarchy must always use the If option.
If you want to set the particle color when it gets to a specific age (older than 90 frames, for example), you would use an If question of the particle’s age, along with a Set Color action as its child.
The question is asked every frame and the Set Color action is only triggered when the condition of the question is passed.
nxQuestion_Basic Settings_01_Particle Age.mp4
This particle age question is set to the default If option. The hierarchy translates to: ‘If the particle age is greater than 90 frames, then set the color to blue.’
Else If questions **can only be used when following an If question.
You can think of it as a follow-up question, which is only asked if the answer to the preceding If question is ‘no’.
An Else If question can be added to the previous example to trigger more particle color changes at another specified particle age.
nxQuestion_Basic Settings_02_Else If.mp4
When each particle is less than 60 frames old, in this animation, the first If question is not passed. Therefore, the follow-up Else If question is asked, but this too fails to pass. As a result, the particle’s color doesn’t change. After frame 60, the first If question is still not passed. However, now the follow-up Else If question is passed and the particles are turned pink. After frame 90, the first If question is finally passed and the particles are turned blue.