spritePool = new Sprite[MAX_SPRITES];
    vertexData = new float[3*6*MAX_SPRITES]; //6 vertices por sprite
    ByteBuffer vbb = ByteBuffer.allocateDirect(vertexData.length * 4); 
    vbb.order(ByteOrder.nativeOrder());
    vertexBuffer = vbb.asFloatBuffer();

      /*
       *    p1              p2
       *      +-----------+
       *      |           |
       *      |           |
       *      |     +     |
       *      |   px,py   |
       *      |           |
       *      +-----------+
       *     p3            p4
       *
       *     p1           p2                 p2 
       *      +-----------+                 -+
       *      |         +                  + |
       *      |       +                  +   |
       *      |     +                  +     |
       *      |   +                  +       | 
       *      | +                  +         |  
       *      +-                 +-----------+
       *     p3                  p3         p4
       *                  
       */
    GL11.glVertexPointer(3, 0, vertexBuffer);
    GL11.glEnableClientState(GL11.GL_VERTEX_ARRAY);
    GL11.glDrawArrays(GL11.GL_TRIANGLES,0,totalSprites*6);
    GL11.glDisableClientState(GL11.GL_VERTEX_ARRAY);

    GL11.glEnable(GL11.GL_BLEND);
    GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);

    GL11.glEnable(GL11.GL_TEXTURE_2D);
    GL11.glBindTexture(GL11.GL_TEXTURE_2D, textureId);  

Transform3D trns = new Transform3D();
Point3D center = "position of player"
Point3D eye = "position of player + x distance over his head"  

Vector3D up ="forward direction of the player"  //assuming Z axis as Up in the game world , this vector must be in X/Y plane

trns.lookAt(eye, center, up);

targetTG.setTransform(trns);

//g2 is a Graphics2D object
//p is a Player object
//map is a Map(TileMap) object
Arc2D.Double arc = new Arc2D.Double();
arc.setArcByCenter(p.getLightX(), p.getLightY(), radius, p.getAngle()-spread, 2*spread, Arc2D.PIE);
GradientPaint gp = new GradientPaint(p.getLightX(),p.getLightY(),new Color(0,0,0,0),
    p.getLightX()+radius*(float)Math.cos(Math.toRadians(p.getAngle())),p.getLightY()-radius*(float)Math.sin(Math.toRadians(p.getAngle())),new Color(0,0,0));
g2.clip(arc);
map.drawTo(g2);
g2.setPaint(gp);
g2.fill(arc);
g2.draw(arc);
g2.setClip(null);

define cone of light;
use cone for clipping;
draw scene;
define gradient (transparente to black) in the direction of light
paint the cone with the gradient;

void swap(int[][] a, int x, int y){
  int[] t = a[x];
  a[x] = a[y];
  a[y] = t;
}