Since the birth of cinema, acting and visual effects have seemed to be in a tug of war, pulling movies in opposite directions.

Actors give films their humanity and heart. Visual effects let the audience see things that no camera could capture. So the battle lines were drawn: soul vs. spectacle.

Yet in recent years, the warring camps have found common ground. Visual effects are letting actors do more and, in some cases, making their workdays shorter and less painful.

Actors were essential in the creation of such digital characters as Gollum in the “The Lord of the Rings” movies, Sonny in “I, Robot” and Kong in “King Kong,” all clearly “visual effects.” Some animated films have even used performance capture to lend life to characters that aren’t remotely human, such as the penguins in “Happy Feet.”

So actors are finding that their old enemy, vfx, instead of overshadowing them — or, as some feared, making them obsolete — is actually expanding their opportunities. Along the way, too, some actors are learning to actually like working with visual effects.

Thesp Bill Nighy, who played Davy Jones, the villain in Disney’s “Pirates of the Caribbean: Dead Man’s Chest,” got his first taste of hybrid performance-capture acting for the film; he was completely erased and replaced with a 100% digital image. Nonetheless, says helmer Gore Verbinski, Nighy’s work was absolutely essential to creating the character.

“I think visual effects don’t exist without good acting,” Verbinski says. “I don’t think Davy Jones exists without Bill Nighy’s performance.”

Nighy himself had been skeptical at first about how much of his work would actually make it onto the screen. Verbinski and the ILM team had shown him conceptual art of the octopus-headed, tentacle-bearded character and promised the subtleties of his acting would be retained, but Nighy says, “I was never sure that technologically it was possible.”

In truth, neither was Verbinski, who admits that he was lying when he assured Nighy, “It’ll be fantastic.” In fact, he knew “it could be a disaster,” since ILM was employing a new performance-capture system and there was no time for a thorough test.

Nighy came to the shoot with an idea about what to expect. He’d played a vampire in the “Underworld” pics using traditional makeup. In such makeup, “you’re limited by how good the makeup is,” he says. “Once you’re inside that thing, the thing is the performance. You’re left entirely with the vocal performance.”

His “Underworld” makeup required six hours to apply and a couple of excruciating hours to remove. Right from the start, his “Pirates” experience was different: He went to work in what he calls “deeply embarrassing and lame-looking computer pajamas, and skullcap, and white dots on your face.”

But ILM’s system let him play his scenes opposite the other actors with the first unit. “It’s incredibly liberating,” Verbinski says. “The other choices in the day would have been lock off the camera, do motion control, bring in bluescreens or go back and do traditional motion capture on a stage that’s a sterile environment.”

“Liberating” is a word many use to describe the new visual effects techniques, even when motion capture isn’t involved.

Brandon Routh, the Man of Steel in “Superman Returns,” found that the digital effects freed him from considerable time in the flying harness, an apparatus with which he says he developed a “love-hate relationship.”

Digital touch-ups also spared Routh extra takes, since a wrinkle in the costume or eyes made red by the wind in his face could be fixed in post.

Both Routh and the vfx crew were on a learning curve in creating the flying sequences, since few films call for a Superman-style flying man. (The “Matrix” films did, and some vets of that trilogy worked on “Superman Returns.”) For some of the more extreme action shots, he was replaced by a digital double, but close-ups, he says, are all live action.

On “X-Men: The Last Stand,” thesps Patrick Stewart and Ian McKellen were digitally altered to look 25 years younger for a flashback sequence. Henry Winkler and Julie Kavner in “Click” got similar treatment. “X-Men” helmer Brett Ratner calls the rejuvenation “a subtle thing” and quips, “I’m sure it’s going to end up in everybody’s contract.”

The technique can spare the actors, cinematographers and hair and makeup people a lot of time and effort while opening up new storytelling possibilities, since such flashbacks can now be done more convincingly.

Still, says Verbinski, performance-capture acting, like Nighy’s work as Davy Jones, is not for everyone: “There is a type of actor who goes back to the monitor and looks at his performance, actors who review themselves endlessly. When you compound that exponentially by having to deal with the visual effects aspect, I think that there are too many opinions. There’s a lot of choices that can be made down the road. Those are choices that can be made very nicely between the animators and director. I don’t like having actors come into that process to lean over your shoulder, I don’t think that’s healthy.”

Nighy and Routh, though, seem to be pleased with how it all came out this year.

Routh felt he was far better at flying by the time the film wrapped, and says, “I’d like to do even more flying in the sequel, because it tells the story better and keeps you in the film.”

Nighy says, “When I finally saw the creature, I was shocked and affected that they should have chosen to inform the creature to such an incredible degree with the performance I’d given on the set.

“I owe everybody at ILM dinner, more than one dinner,” he says, adding that in the upcoming third “Pirates” pic, “You certainly approach it with more confidence, and you’re emboldened, in that stuff you do in acting terms generally will arrive onscreen, albeit as interpreted by the creature. But it will be there. “

Verbinski, too, has reassuring words for actors: “There’s a point in the process where things have to be singular, they have to be from one person’s point of view. I think you get that from an actor’s performance, and not with a committee of animators and animation directors and even from myself. It’s just too much to go through to say, ‘Let’s create nuance from scratch.’ You need somebody to start it. We’re always going to need great acting.”

For his part, Nighy is optimistic about the possibilities these new techniques open up.

“They can enlarge an actor’s experience,” he says. “There are so many stories we’re going to want to tell that require those kind of skills and those kind of images, and I see no reason why actors and CGI can’t work hand in hand. There’s no reason one should threaten the other.”