Has my fast been invalidated due to a transparent, viscous, yellowish, and oddly-scented fluid being discharged after viewing pornographic images, and do I need to perform ghusl and purify my clothes?

You must repent to Allah for intentionally looking at what is forbidden. Your fast is valid, Allah willing, as long as you are not certain that semen has exited. If you are unsure whether the discharge is semen or pre-seminal fluid, you have the choice to assign it the ruling you wish.