极限渲染速度

Question

I have this method here which renders my players movement. It swaps between 3 images, standing, left leg forward, and right leg forward.

It swaps images very fast so how can I change the speed of the rendering?

public static void renderUpwardWalking() {
    ImageIcon[] frames = { CharacterSheet.up, CharacterSheet.upLeftLeg,
            CharacterSheet.upRightLeg };

    if (Key.up && Character.direction == "up") {
        currentFrame++;
        if (currentFrame == 3)
            currentFrame = 1;
        Character.character.setIcon(frames[currentFrame]);
    } else if (!Key.up && Character.direction == "up") {
        currentFrame = 0;
    }
}

Answer 1

You can change the scale of your currentFrame counter, and use its range to control your frame rate:

 //Let  this go from 1...30
 int currentFrameCounter;


 .
 .
 .
 currentFrameCounter++;
 if(currentFrameCounter == 30) currentFrameCounter = 0;

 //Take a fraction of currentframeCounter for frame index  ~ 1/10 frame rate
 //Note care to avoid integer division
 currentFrame = (int) (1.0*currentFrameCounter / 10.0);  

Putting it all together in a general model:

 int maxCounter = 30; //or some other factor of 3 -- controls speed


 int currentFrameCounter;

 public static void renderUpwardWalking() {
     ImageIcon[] frames = { CharacterSheet.up, CharacterSheet.upLeftLeg,
        CharacterSheet.upRightLeg };

     if (Key.up && Character.direction == "up") {

         currentFrameCounter++;  //add
         if(currentFrameCounter == maxCounter) currentFrameCounter = 0;             
         currentFrame = (int) (1.0*currentFrameCounter / (maxCounter/3.0));  
         Character.character.setIcon(frames[currentFrame]);
     } else if (!Key.up && Character.direction == "up") {
         currentFrame = 0;
     }

}

Answer 2

This is usually done on timer.

1. Decide on a frame pattern and a frequency. You seem to have chosen the frame pattern CharacterSheet.up, CharacterSheet.upLeftLeg, CharacterSheet.upRightLeg. Let's say you want to swap frame every 400 ms.

2. Get the time from a clock with sufficient resolution. System.nanoTime() is usually accurate enough.

long frameTime = 400L * 1000000L; // 400 ms in nanoseconds long frameTime = 400L * 1000000L; // 400 ms in nanoseconds Edit

currentFrame = (System.nanoTime() / frametime) % frames.length;