Is ghusl required if semen is discharged merely by looking at something arousing?

If semen is discharged with desire, whether due to looking, touching, or other reasons, then ghusl (ritual bath) becomes obligatory by consensus. There is no difference whether its discharge is due to intercourse, a wet dream, masturbation, or looking, and whether it is discharged with desire or without, or whether one enjoys its discharge or not, or whether it is much or little, or in sleep or wakefulness.