/*********************************************************************

          OpenGL(MesaGL) (+ GLUT) sample program

                                        Kenji with Tail

*********************************************************************/

#include <math.h>
#include <GL/glut.h>

/* 視点の方向、距離(のための変数) */
double er = 0, ef = 5;

void idle(void)
{
  glutPostRedisplay();
}

/* 円柱を描く */
void drawobj(void)
{
  int i;
  static int flag = 0;
#define DIV 36
  static GLdouble vertex[DIV+1][3];

  /* 一回目の呼出時のみ初期化 */
  if (flag == 0) {
    for (i = 0; i < DIV; i++){
      vertex[i][0] = cos(PI * 2 * i / DIV);
      vertex[i][1] = sin(PI * 2 * i / DIV);
      vertex[i][2] = 0;
    }
    vertex[i][0] = vertex[0][0];
    vertex[i][1] = vertex[0][1];
    vertex[i][2] = vertex[0][2];
    flag = 1;
  }
    
  /* 実際の描画 */
  glBegin(GL_QUADS);
  for (i = 0; i < DIV; i++) {
    glNormal3dv(vertex[i]);
    glVertex3d(vertex[i][0], vertex[i][1], 2.0);
    glVertex3dv(vertex[i]);
    glNormal3dv(vertex[i+1]);
    glVertex3dv(vertex[i+1]);
    glVertex3d(vertex[i+1][0], vertex[i+1][1], 2.0);
  }
  glEnd();
}

void display(void)
{
  int i, j;
  static int r = 0;
  /* 床座標の設定 */
  GLdouble vertex[][3] = {
    { 1.0, -.1, 1.0 }, { 1.0, -.1,-1.0},
    {-1.0, -.1,-1.0 }, {-1.0, -.1, 1.0},
    { 0.0, 1.0, 0.0 } /* <- 法線ベクトル */
  };
  GLfloat lpos[4] = {0.0, 2.5, 5.0, 0.0};
  GLfloat mcolr[4] = {0.7, 0.2, 0.2, 1.0};
  GLfloat mcolg[4] = {0.2, 0.7, 0.2, 1.0};
  GLfloat mcolb[4] = {0.2, 0.2, 0.7, 1.0};
  
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  /* マトリクスの保存(視点視線情報を含んでいない) */
  glPushMatrix();

  /* 視点、視線方向の設定 */
  gluLookAt(cos(er)*ef, ef, sin(er)*ef, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  glLightfv(GL_LIGHT0, GL_POSITION, lpos);

  /* 床の描画 */
  glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, mcolg);
  glBegin(GL_QUADS);
  glNormal3dv(vertex[4]);
  for (i = 0; i < 4; i++){
    glVertex3dv(vertex[i]);
  }
  glEnd();
  
  /* 視点視線情報を含んだマトリクスの保存 */
  glPushMatrix();

  /* 赤色の円柱 */
  glScaled(.5, .5, .5);
  glTranslated(0.0, 1.0, 0.0);
  glRotated((GLdouble)r, 0.0, 1.0, 0.0);
  glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, mcolr);
  drawobj();

  /* 赤色の円柱の上の一緒に動く青色の円柱 */
  glScaled(.5, .5, .5);
  glTranslated(0.0, 3.0, 4.0);
  glRotated((GLdouble)r, 0.0, 1.0, 0.0);
  glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, mcolb);
  drawobj();
  
  /* 視点視線情報を含んだマトリクスの復帰 */
  glPopMatrix();

  /* 赤色の円柱とは別に動く緑色の円柱 */
  glScaled(.15, .15, .15);
  glTranslated(0.0, 4.0, 0.0);
  glRotated((GLdouble)r, 1.0, 0.0, 0.0);
  glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, mcolg);
  drawobj();

  /* 視点視線情報を含んでいないマトリクスの復帰 */
  glPopMatrix();

  glutSwapBuffers();
  if (++r >= 360) r = 0;
}

void resize(int w, int h)
{
  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(30.0, (GLdouble)w/h, 1.0, 100.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
  if (key == '\033') exit(0);
}

/* マウスボタンにより視点情報を変更 */
void mouse(int button, int state, int x, int y)
{
  switch (button) {
  case GLUT_LEFT_BUTTON:
    if (state == GLUT_UP) er += .1;
    /* if (er >= 2*PI) er = 0; */
    break;
  case GLUT_MIDDLE_BUTTON:
    if (state == GLUT_UP) ef += .2;
    break;
  case GLUT_RIGHT_BUTTON:
    if (state == GLUT_UP) ef -= .2;
    if (ef < 1) ef = 1;
    break;
  }
}

int main(int argc, char *argv[])
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
  glutCreateWindow(argv[0]);
  glClearColor(1.0, 1.0, 1.0, 0.0);
  glutDisplayFunc(display);
  glutKeyboardFunc(keyboard);
  glutMouseFunc(mouse);
  glutIdleFunc(idle);
  glutReshapeFunc(resize);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glutMainLoop();
}