Hello I am Taiwan student
recently I start to use processing~
I use opnegl light to do this:




import javax.media.opengl.*;
import processing.opengl.*;
import java.nio.*;
import com.sun.opengl.util.*;


PGraphicsOpenGL pgl;
GL gl;

FloatBuffer lightKa;
FloatBuffer lightKd;
FloatBuffer lightKs;
FloatBuffer light_position;
void setup()
{
  size(400,300,OPENGL);
  pgl = (PGraphicsOpenGL) g;  // g may change
  gl = pgl.gl;
  lightKa = BufferUtil.newFloatBuffer(4);
  lightKa.put(0.2);
  lightKa.put(0.2);
  lightKa.put(0.2);
  lightKa.put(1.0);
  lightKa.rewind();

  lightKd = BufferUtil.newFloatBuffer(4);
  lightKd.put(0.7);
  lightKd.put(0.7);
  lightKd.put(0.7);
  lightKd.put(1.0);
  lightKd.rewind();

  lightKs = BufferUtil.newFloatBuffer(4);
  lightKs.put(1.0);
  lightKs.put(1.0);
  lightKs.put(1.0);
  lightKs.put(1.0);
  lightKs.rewind();

  light_position = BufferUtil.newFloatBuffer(4);
  light_position.put(0.0);
  light_position.put(0.0);
  light_position.put(100.0);
  light_position.put(0.0);
  light_position.rewind();


  // set up light colors (ambient, diffuse, specular)
  gl.glLightfv(GL.GL_LIGHT0, GL.GL_AMBIENT, lightKa);
  gl.glLightfv(GL.GL_LIGHT0, GL.GL_DIFFUSE, lightKd);
  gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPECULAR, lightKs);

  // position the light
   float[] dir =new float[]{
   0.0f, 0.0f, -1f,0.0f};
  gl.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, light_position);
  gl.glLightfv(GL.GL_LIGHT0, GL.GL_SPOT_DIRECTION, dir,0);
  gl.glEnable(GL.GL_LIGHT0);                      
}

void draw()
{
  background(0);
  camera(mouseX,mouseY,300,
  0,0,0,
  0,1,0);
  Draw_Box(0,0,0,100,1,1,1,1);
}

//    v6----- v5
//   /|      /|
//  v1------v0|
//  | |     | |
//  | |v7---|-|v4
//  |/      |/
//  v2------v3
void Draw_Box(float CenterX,float CenterY,float CenterZ, float R,
float Enter_H,float Enter_S, float Enter_B,float Enter_ColorA)
{
  gl = pgl.beginGL();

  gl.glBegin(GL.GL_QUADS);

  // v0-v1-v6-v5
  gl.glNormal3f(0,1,0);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ-R);  // v6
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ-R);  // v5
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ+R);  // v0
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ+R);  // v1


  // v2-v3-v4-v7
  gl.glNormal3f(0,-1,0);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ-R);  // v7
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ-R);  // v4
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ+R);  // v3
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ+R);  // v2


  // v0-v3-v4-v5
  gl.glNormal3f(1,0,0);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ+R);  // v0
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ+R);  // v3
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ-R);  // v4
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ-R);  // v5


  // v1-v2-v7-v6
  gl.glNormal3f(-1,0,0);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ+R);  // v1
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ+R);  // v2
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ-R);  // v7
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ-R);  // v6


  // v1-v0-v2-v3
  gl.glNormal3f(0,0,-1);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ+R);  // v1
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ+R);  // v0
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ+R);  // v2
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ+R);  // v3


  // v6-v5-v4-v7
  gl.glNormal3f(0,0,-1);
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY-R,CenterZ-R);  // v6
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY-R,CenterZ-R);  // v5
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX+R,CenterY+R,CenterZ-R);  // v4
  gl.glColor3f(0,1,0);
  gl.glVertex3f(CenterX-R,CenterY+R,CenterZ+R);  // v7

  gl.glEnd();
  pgl.endGL();
}



but it has no shadow like this:


import processing.opengl.*; 
 
void setup() 
{ 
  size(400, 300, OPENGL); 
} 
 
void draw() 
{ 
  camera(mouseX,mouseY,300,
  0,0,0,0,1,0);
  background(0);
  directionalLight(126, 126, 126, 0, 0, -1);
  ambientLight(64,64,64);
  noStroke();
  fill(0,255,0);
  box(100);
} 



I don't know why~~~~Please help me~~~