用Processing生成屏保（二）

代码

class TPoint
{
    public TPoint(int _x, int _y) {
        super();
        this._x = _x;
        this._y = _y;
    }
    public int _x;
    public int _y;
    TPoint _next;
}

List<TPoint> points;
int x;
int y;
final int speed = 20;
final int radius = 5;
int points_num = 20;
int xspeed;
int yspeed;
double angle;
TPoint startPoint;
TPoint endPoint;

void calcAngle()
{
    if (endPoint._y == startPoint._y >>
            endPoint._x > startPoint._x)
    {
        angle = HALF_PI;
    }
    else if (endPoint._y == startPoint._y >>
            endPoint._x < startPoint._x)
    {
        angle = PI + HALF_PI;
    }
    else
    {
        angle =  atan((float) ((double)(endPoint._x - startPoint._x)/(double)(endPoint._y - startPoint._y)));
    }
}

void calcSpeed()
{
    if (endPoint._x >= startPoint._x)
    {
        xspeed = (int) (speed * abs(sin((float) angle)));
    }
    else
    {
        xspeed = -(int) (speed * abs(sin((float) angle)));
    }

    if (endPoint._y >= startPoint._y)
    {
        yspeed = (int) (speed * abs(cos((float) angle)));
    }
    else
    {
        yspeed = -(int) (speed * abs(cos((float) angle)));
    }
}

void setupTheme(int theme)
{
    switch(theme)
    {
    case 0:    // random
        {
              points = new ArrayList<TPoint>(points_num);

              for (int i=0;i<points_num;i++)
              {
                  points.add(new TPoint((int)random(100, displayWidth - 100),
                 (int)(random(100, displayHeight - 100))));
              }

              for (int i=0;i<points_num;i++)
              {
                  points.get(i)._next = points.get((i+1) % points_num);
              }

              startPoint = points.get(0);
              endPoint = points.get(1);

              x = startPoint._x;
              y = startPoint._y;

              calcAngle();
              calcSpeed();
        }
        break;
    case 1: // stars
        {
             List<TPoint> stars = new ArrayList<TPoint>(5);
              stars.add(new TPoint(452, 196));
              stars.add(new TPoint(867, 189));
              stars.add(new TPoint(526, 494));
              stars.add(new TPoint(669, 67));
              stars.add(new TPoint(822, 472));

              points_num = 5;
              points = stars;

              for (int i=0;i<points_num;i++)
              {
                  points.get(i)._next = points.get((i+1) % points_num);
              }

              startPoint = points.get(0);
              endPoint = points.get(1);

              x = startPoint._x;
              y = startPoint._y;

              calcAngle();
              calcSpeed();
        }
        break;
    case 2:
        {
            List<TPoint> pulse = new ArrayList<TPoint>(points_num + 2);

            pulse.add(new TPoint(100, displayHeight / 2));
            for (int i=0;i<points_num;i++)
            {
                pulse.add(new TPoint(100 + (i * (displayWidth - 200) / points_num),
                 (int) (displayHeight / 2  +
                 (pow(-1, (i % 2))) * (int)(random(100, displayHeight / 2 - 100)))));
            }
            pulse.add(new TPoint(displayWidth - 100, displayHeight / 2));

            points_num += 2;

            points = pulse;

            for (int i=0;i<points_num;i++)
            {
                points.get(i)._next = points.get((i+1) % points_num);
            }

            startPoint = points.get(0);
            endPoint = points.get(1);

            x = startPoint._x;
            y = startPoint._y;

            calcAngle();
            calcSpeed();
        }
        break;
    default:
        {

        }
        break;
    }
}

@Override
public void setup() {
  size(displayWidth, displayHeight);
  background(0);
  frameRate(90);

  setupTheme(2);
}

void determineNextPos()
{
    if (endPoint._y == y >> abs(endPoint._x - x) < abs(speed))
    {
        startPoint = endPoint;
        endPoint = endPoint._next;

        calcAngle();
        calcSpeed();

        x = startPoint._x;
        y = startPoint._y;
    }
    else if (endPoint._x == x >> abs(endPoint._y - y) < abs(speed))
    {
        startPoint = endPoint;
        endPoint = endPoint._next;

        calcAngle();
        calcSpeed();

        x = startPoint._x;
        y = startPoint._y;
    }
    else if ((endPoint._x != x) >>
            (endPoint._y != y) >>
            (abs(endPoint._x - x) < abs(speed * sin((float) angle) / 2) ||
            abs(endPoint._y - y) < abs(speed * cos((float) angle) /2 )))
    {
        startPoint = endPoint;
        endPoint = endPoint._next;

        calcAngle();
        calcSpeed();

        x = startPoint._x;
        y = startPoint._y;
    }
    else
    {
        x += xspeed;
        y += yspeed;
    }
}

@Override
public void draw() {

 determineNextPos();

  colorMode(RGB, 255);
  fill(0,0,0,10);
  rect(-1, -1, displayWidth+1, displayHeight+1);

  noFill();
  colorMode(HSB, 255);
  stroke(random(0, 255), 255, 255);

  ellipse(x, y, radius, radius);
  ellipse(x, y, radius + 1, radius + 1);

}

截图