/*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
   gluthack.h の利用例のプログラム   製作 渡辺尚貴
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*/

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "gluthack.h"

//---- 描画のパラメタ
const double   L            = 8.0;                    // 系のサイズ
const int      N            = 32;                     // データの要素数
const double   dL           = L/N;                    // 空間刻幅

const int      WIN_WID      = 256;                    // 窓の横幅
const int      WIN_HEI      = 256;                    // 窓の縦幅
const GLfloat  WIN_COL[]    = { 0.0, 0.0, 0.0, 1.0 }; // 背景の色
const GLdouble EYE_POS[]    = { 0.0, 0.0, 2*L };      // 視点の位置
const GLdouble GAZE_POS[]   = { 0.0, 0.0, 0.0 };      // 凝視点の位置
const GLdouble UP_DIR[]     = { 0.0, 1.0, 0.0 };      // 鉛直方向
const GLdouble SCOPE_ANG    = 32.0;                   // 視野角
const GLdouble SCOPE_NEAR   = L/2;                    // 近視野距離
const GLdouble SCOPE_FAR    = 6*L;                    // 遠視野距離
const GLfloat  LIGHT_POS[]  = { 0.0, 0.0, 2*L };      // 照明位置
const GLfloat  LIGHT_DIF[]  = { 1.0, 1.0, 1.0, 1.0 }; // 拡散光の色
const GLfloat  LIGHT_SPE[]  = { 1.0, 1.0, 1.0, 1.0 }; // 反射光の色
const GLfloat  LIGHT_AMB[]  = { 0.8, 0.8, 0.8, 1.0 }; // 環境光の色
const GLfloat  OBJ_COL[]   = { 0.5, 0.5, 0.8, 0.5 };  // 物体の拡散色
const GLfloat  OBJ_SPE[]   = { 1.0, 1.0, 1.0, 1.0 };  // 物体の反射色
const GLfloat  OBJ_SHIN    = 256.0;                   // 物体の反射強度





enum { LIST_ZERO, LIST_WIRE, LIST_SURFACE, LIST_VECTOR, LIST_TEXTURE };
enum { MENU_SCREEN, MENU_LIST, MENU_QUIT };

//---- 種々の状態変数
static bool do_screen  = false;       // フルスクリーンで描くか
static int  draw_list  = LIST_WIRE;   // 描く物体

//---- データ格納用の変数
static double  Z[N][N];
static Vector2 V[N][N];
static Texture tex;

//---- 簡単な解説
void PrintUsage( void )
{
  puts(
       "------------------------------------\n"
       "gluthack.h の利用例のプログラム\n"
       "------------------------------------\n"
       "操作方法:\n"
       "左ドラッグで物体が回転し始めます。\n"
       "右クリックでメニューが現れます。\n"
       "方向キーで物体が移動します。\n"
       "sキーで画面がファイルに保存されます。\n"
       "ESCキーで終了です。\n"
       );
}

//---- 描く物体のデータの作成
void InitData( void )
{
  const double kx = 2*M_PI/L;
  const double ky = 2*M_PI/L;

  int i, j;
  for( i=0; i<N; i++ ){
    for( j=0; j<N; j++ ){
      Z[i][j] = 0.25 * sin( i*dL * kx ) * sin( j*dL * ky );
    }
  }

  for( i=0; i<N; i++ ){
    for( j=0; j<N; j++ ){
      V[i][j].x = - (1.0/16) * ( j*dL - L/2 );
      V[i][j].y = + (1.0/16) * ( i*dL - L/2 );
    }
  }
}


//---- 描画する物体の作成
void MakeList( void )
{

  // ワイアーフレームの物体の作成
  glNewList( LIST_WIRE, GL_COMPILE );{
    glPushMatrix();{
      glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR,            OBJ_SPE  );
      glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, OBJ_COL  );
      glMaterialf(  GL_FRONT_AND_BACK, GL_SHININESS,           OBJ_SHIN );

      glTranslated( -L/2, -L/2, 0.0 );
      glScaled( L, L, L );
      glutWireNet( (double*)Z, N );
    }glPopMatrix();
  }glEndList();

  // 曲面の物体の作成
  glNewList( LIST_SURFACE, GL_COMPILE );{
    glPushMatrix();{
      glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR,            OBJ_SPE  );
      glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, OBJ_COL  );
      glMaterialf(  GL_FRONT_AND_BACK, GL_SHININESS,           OBJ_SHIN );

      glTranslated( -L/2, -L/2, 0.0 );
      glScaled( L, L, L );
      glutSurface( (double*)Z, N );
    }glPopMatrix();
  }glEndList();

  // ベクトル場の物体の作成
  glNewList( LIST_VECTOR, GL_COMPILE );{
    glPushMatrix();{
      glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR,            OBJ_SPE  );
      glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, OBJ_COL  );
      glMaterialf(  GL_FRONT_AND_BACK, GL_SHININESS,           OBJ_SHIN );

      glTranslated( -L/2, -L/2, 0.0 );
      glScaled( L, L, L );
      glutVector( (Vector2*)V, N );
    }glPopMatrix();
  }glEndList();

  // テクスチャの物体の作成
  if( glutReadTexture( "texture.ppm", tex ) ){
    perror("glutReadTexture");
    exit(1);
  };
  glutSetTexture( tex );

  glNewList( LIST_TEXTURE, GL_COMPILE );{
    glPushMatrix();{
      const GLfloat color[4]    = { 0.8, 0.6, 0.2, 0.6 };
      const GLfloat specular[4] = { 1.0, 1.0, 1.0, 1.0 };

      glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR,            specular );
      glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, color    );
      glMaterialf(  GL_FRONT_AND_BACK, GL_SHININESS,           16.0     );

      glEnable(GL_TEXTURE_2D);
      glTranslated( -L/2, -L/2, 0.0 );
      glScaled( L, L, L );
      glBegin(GL_QUADS);{
	glNormal3d( +1,  0,  0 );
	glTexCoord2f( 0.0,  0.0);	glVertex3d( 0.0, 0.0, 0.0 );
	glTexCoord2f( 0.0,  4.0);	glVertex3d( 0.0, 1.0, 0.0 );
	glTexCoord2f( 4.0,  4.0);	glVertex3d( 1.0, 1.0, 0.0 );
	glTexCoord2f( 4.0,  0.0);	glVertex3d( 1.0, 0.0, 0.0 );
      }glEnd();
      glDisable(GL_TEXTURE_2D);
    }glPopMatrix();
  }glEndList();
}




/*********** OpenGL の callback の定義 **********************/

double dthe = 0.0, dphi = 0.0;

//---- 必要時に描画を行う callback
void myDisplay(void)
{
  glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

  glPushMatrix();{
    glCallList( draw_list );
  }glPopMatrix();

  glFlush();
  glutSwapBuffers();
}


//---- idle時に計算を行うcallback
void myIdle( void )
{
  glRotateL(dthe, 1.0, 0.0, 0.0 );
  glRotateL(dphi, 0.0, 1.0, 0.0 );
  glutPostRedisplay();
}

//---- Mouseの callback
void myMouse( int button, int state, int x, int y )
{
  static int xs=0, ys=0, xe, ye;
  
  if( button == GLUT_LEFT_BUTTON ){
    if( state == GLUT_DOWN ){
      xs = x, ys = y;
    }else if( state == GLUT_UP ){
      xe = x, ye = y;
      dthe = double(ye-ys)/16;
      dphi = double(xe-xs)/16;
      xs = xe, ys = ye;

      if( dthe == 0.0 && dphi == 0.0 ){
	glutIdleFunc( NULL );
      }else{
	glutIdleFunc( myIdle );
      }
    }
  }
}


//---- キーボードのcallback
void myNormalKey( int k, int x, int y )
{
  switch( k ){
    case 's'            :{
      static int cell = 1;
      char* fname = glutSaveWindow( "clip%02d.ppm", cell++ );
      fprintf( stderr, "Save the image in file %s\n", fname );
      return;
    }
  }
  glutPostRedisplay();
}
void mySpecialKey( int k, int x, int y )
{
  switch( k ){
    case GLUT_KEY_LEFT  : glTranslateL( -L/8, 0.0, 0.0 ); break;
    case GLUT_KEY_RIGHT : glTranslateL( +L/8, 0.0, 0.0 ); break;
    case GLUT_KEY_UP    : glTranslateL( 0.0, 0.0, +L/8 ); break;
    case GLUT_KEY_DOWN  : glTranslateL( 0.0, 0.0, -L/8 ); break;
    case GLUT_KEY_ESC   : exit(0);
  }
  glutPostRedisplay();
}

//---- メニューのcallback
void myMainMenu( int menu )
{
  switch( menu ){
  case MENU_SCREEN : {
    if( do_screen == true ){
      glutPositionWindow(16,32);
      glutReshapeWindow(WIN_WID, WIN_HEI);
    }else{
      glutFullScreen();
    }
    do_screen = !do_screen;
  } break;

  case MENU_QUIT : {
    exit(0);
  } break;
  }
}

void mySubMenu( int list )
{
  draw_list = list;
  glutPostRedisplay();
}


/*********** メイン関数 ***********/
int main( int argc, char* argv[] )
{
  glutOpenWindow( argc, argv, WIN_WID, WIN_HEI, WIN_COL );
  glutSetEye( SCOPE_ANG, SCOPE_NEAR, SCOPE_FAR, EYE_POS, GAZE_POS, UP_DIR );
  glutSetLight( LIGHT_POS, LIGHT_AMB, LIGHT_DIF, LIGHT_SPE );

  int submenu = glutCreateMenu( mySubMenu );{
    glutAddMenuEntry( "Wireframe", LIST_WIRE );
    glutAddMenuEntry( "Surface",   LIST_SURFACE );
    glutAddMenuEntry( "Vector",    LIST_VECTOR );
    glutAddMenuEntry( "Texture",   LIST_TEXTURE );
  }
  int mainmenu = glutCreateMenu( myMainMenu );{
    glutAddMenuEntry( "Window / Screen", MENU_SCREEN );
    glutAddSubMenu(   "Change object",   submenu );
    glutAddMenuEntry( "Quit",            MENU_QUIT );
  }
  glutAttachMenu( GLUT_RIGHT_BUTTON );

  PrintUsage();
  InitData();
  MakeList();

  glutMainLoop();

  return 0;
}