The golfers of the future displayed their plumage on the golf course of the future this afternoon.

John Cook, Bobby Clampett and Peter Jacobsen, a trio of young three-time all-Americas, rose to the top at the midpoint of the Tournament Players Championship today. The three, all known for their ability to make a golf ball do tricks, demonstrated the sort of gifted, gaudy yet often goofy golf that may become a trademark of the sport in the '80s.

The 25-year-old Cook hit the first 17 greens in regulation in his round of 70, taking a two-shot lead at five-under-par 139 entering Sunday's 36-hole marathon finish. Clampett (72) and Jacobsen, whose 68 was the day's only round under 70, were in a four-way tie for second place at 141 with two longshots--J.C. Snead (70) and Don Pooley (70).

"It's a myth that there are no more great ball-strikers coming along. Anybody who says there are no more workers of the ball, no more players who can invent shots and curve the ball any way they want, is crazy," said Cook, who sank a 50-foot bunker shot for a birdie on the second hole.

"Some of the older players come here (to the controversial Players Club) moanin' and groanin,' " continued Cook, who is almost as pure a swinger as the tour owns. "I don't like to see that, because I respected them so much growing up. But, if they're going to moan and groan, that's just too bad for them. Things are changing. The younger players out here have learned a lot . . . "

This TPC, with its $126,000 first prize, has been a perfect proving ground for the tour's imaginative young swingers. While many of the game's most famous veteran names have seemed both mentally strained and emotionally drained by this 6,857-yard purgatorial layout, the daring young men here have prospered.

For instance, Clampett, the fellow who likes to hit 250-yard drives from a kneeling position, disappeared entirely from view into a deep pop bunker beside the seventh hole this afternoon. All the crowd saw was Clampett's backswing and a puff of sand. Next, the 22-year-old was dashing up the bank just in time to see his ball dive into the hole 75 feet away for a miraculous birdie.

Another from this school of bravado is Jacobsen, who can and does imitate the swings and mannersims of all the tour's famous stars; this gimmick has helped him play any sort of shot. In his 68, Jacobsen rattled off four birdies in six holes at one stretch.

For once, veterans don't have what Cook called "the big advantage" of local knowledge, plus years of experience in playing a particular layout; nobody's got this place wired yet and the youngsters are doing a better job of adapting.

While legends like Arnold Palmer (72), Jack Nicklaus (76) and Tom Watson (74), who all have 149, had to struggle to hit the cut on the nose, the up-and-comers, like Vance Heafner, Lennie Clements and Hal Sutton, were poised for the finish.

Heafner (71) and Clements (70)--another pair of former all-Americas in their mid-20s--were tied with first-round leader Bruce Lietzke (75) and Tommy Nakajima (72) at 143. Sutton (71) and Ben Crenshaw were part of an eight-way logjam at 144. Tucked at 142 was the true exception to the day's rule, 40-year-old Bob Murphy (70).

If you can hit the low, boring draw into the wind, then follow it with a high fluttering fade with the breeze at your back; if you can snap-hook a ball around a tree out of heavy rough, or punch-slice a shot under a live oak limb, then the Players Club is the place for you. With 36 holes on tap for Sunday, it may also help to be young.

"It's a grind. Those in the best shape should have an edge," said the 6-foot, 160-pound Cook, who often played double rounds in college events. "Tomorrow is survival. We'll see who can keep themselves in it mentally for 10 hours . . . It'll be like being back in the old (college) days again."

Many a pro didn't survive this sunny but very breezy day. Fred Couples took 10 at the 11th on his way to 81-84--165 and a tie for last place in the field. Andy Bean took eight at the watery fourth and reported an 83.

The diabolical 17th hole claimed 27 wet balls, including four that belonged to Rex Caldwell. Arriving at the hole one under par for the tournament, Caldwell hit his tee shot in the drink on the already famous 132-yard island hole. From the drop area, perhaps 75 yards from the pin, Caldwell splashed two more balls, one short, one long. Finally, after tapping in for a 9, Caldwell, who shot 81, pulled his ball out of the cup and heaved it into the lake so it could join the others.

Fuzzy Zoeller topped Caldwell's fury. First, he drowned one from the tee, then he deep-sixed another from the drop area. After reaching safety with his third shot, Zoeller delighted the blood-thirsty crowd by hurling his traitorous wedge into the lake. After finishing his quadruple bogey, Zoeller chucked his glove and ball in the water, too. Despite this, Zoeller made good on his vow to improve on his 82 of Friday; this time, he shot 80.

For an extra dramatic twist, leader Cook has no idea if he can endure 36 holes in one day. Last year, he tore a tendon in his left elbow and sprained his wrist when he hit a root at the Inverrary Classic.

Now, a year later, he says, "My health is back to 75 percent. Last year, it was zero . . . My arm's a little stiff right now. It could easily give me problems. I'll ice it between rounds so it won't start swelling (as it does after every round). That's my main worry."

When Sunday's ordeal is over and the last limping pro has escaped the last treacherous torment of the Players Club, look for the winner to be very tired. And probably very young.