If EnableStereo(true); is called on SteamVR when stereo is already enabled, it will return false:
bool FSteamVRHMD::EnableStereo(bool bStereo)
{
if( bStereoEnabled == bStereo )
{
return false;
}
But the comment on IStereoRendering::EnableStereo says:
/**
* Switches stereo rendering on / off. Returns current state of stereo.
* @return Returns current state of stereo (true / false).
*/
virtual bool EnableStereo(bool stereo = true) = 0;
The current state of stereo after calling EnableStereo when stereo is already enabled is “true”, so it should return true.