It is rare, while it may happen but the actor in 300: Rise of an Empire while not as ripped as Butler was okay, and that was all that was necessary anyway for the part. He did not look bad.
If they wanted the lead in the new 300 to have a more ripped looked they would have lit it differently and used make up, etc.
They wanted the guys to look exactly like in the first movie, there was no change in their approach. It was very challenging to train Stapleton because he was shooting another series back on another continent unlike Butler and Cavill who basically trained full time for months and lived in a gym.
The result was an OK physique which is kinda a mixed blessing for a 300 film. The extras are all stuntmen and bodybuilders and have these insane physiques, if the lead is being constantly upstaged, you wonder why is he leading the army and not the guy standing next to him - what makes HIM the lead? Butler pretty much had the best physique in 300, an example of a series where the sequel being undone by the precedents set by the original. Even Stapleton's performance was muted so people thought he was a step down from Butler in every way - performance and physicality. In as macho a series as 300, it was a woman who walked away with the film and won all the praise for 300: Rise Of An Empire.
If they want Affleck to look good, he'll get a pump before the scene, light it correctly, use CGI, make up, oil, etc. and use whatever else they need to do to make him look how they want him to look or just not have a shirtless scene. If there is one, and he will not have time to get how they want him to look, and decide they just have to have it, then they will use all they can to make him look right. In a movie like this where the suit makes it look like he is so muscular, they won't have him look bad. People would just say "hey those muscles on the suit are fake", people are dumb enough, they may think those are real muscles.
It ain't all smoke and mirrors, lighting and touch-ups will enhance what is already there, help in presentation, but it won't create something out of thin hair, the body still has to be there pretty much.
The very point of a physique shot in a movie like this is, is that it is an opportunity for the lead actor to get into fantastic shape and be paid for it, an opportunity every man would happily jump at as their is huge masculine vanity associated with having a physique that wows people. Using CGI pretty much kills the inherent point of such a scene. Such scenes are almost never a story requirement - they usually give the actor a vanity shot, sell the image of a superhero as an ideal male which audiences have come to expect and serve as a validation scene for the actor, in that he "earned the super-heroic role" in the eyes of the public.
So there won't be a pressing requirement for a shirtless scene for sure, the movie wouldn't crumble without it. But doing it with CGI would be an unfortunate cop out, and Snyder, who really believes that transforming his actors improves their performances, wouldn't be up for CGIing his actor.
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As for Hardy, he seemed entirely unremarkable. His workout and transformation was very heavily publicized. It makes you go , he needed steroids for
that??