/* Using fog in a scene.

Written by Caroline Geiersbach and Scott D. Anderson
scott.anderson@acm.org
Summer 2003
*/

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

#define barnWidth 30
#define barnHeight 40
#define barnLength 50

void sun() {
  GLfloat lightPosition [] = {1,0.3,0,1};
  GLfloat ambient [] = {0.6,0.6,0.6,1};
  GLfloat diffuse [] = {0.6,0.6,0.6,1};
  GLfloat specular [] = {0.8,0.8,0.8,1};
  glLightfv(GL_LIGHT1, GL_POSITION, lightPosition);
  glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
  glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
  glLightfv(GL_LIGHT1, GL_SPECULAR, specular);
  glShadeModel(GL_SMOOTH);
  glEnable(GL_LIGHT1);
  glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);
  glEnable(GL_LIGHTING);
}

int FogOption = 1;

void fog() {
  glEnable(GL_FOG);
  GLfloat fogColor[4]={0.7,0.7,0.7,1};
  glFogfv(GL_FOG_COLOR,fogColor);
  glHint(GL_FOG_HINT,GL_NICEST);
  switch(FogOption) {
  case 0: 
    printf("Linear Fog\n");
    glFogi(GL_FOG_MODE, GL_LINEAR);
    glFogf(GL_FOG_START, 6);
    glFogf(GL_FOG_END, 10);
    break;
  case 1:
    printf("Exponential Decay Fog\n");
    glFogi(GL_FOG_MODE, GL_EXP);
    glFogf(GL_FOG_DENSITY, 0.25);
    break;
  case 2:
    printf("Gaussian Decay Fog\n");
    glFogi(GL_FOG_MODE, GL_EXP2);
    glFogf(GL_FOG_DENSITY, 0.35);
    break;
  }
}

//colors used
twTriple tireColor = {0.1,0.1,0.1};
twTriple frameColor = {0.9,0,0};

//draws one tire and its spokes
void drawTire() {
  int i;
  glPushMatrix();
  twColor(tireColor,0.9,50.0);
  glutSolidTorus(0.3,3.0,30,30); 
  for(i=0;i<12;i++) {  //spokes
    glRotatef(30,0,0,1);
    twSolidCylinder(0.03,0.03,3.0,10,10);
  }
  glPopMatrix();
}

//draws handlebars
void drawHandlebar() {
  glPushMatrix();
  twSolidCylinder(0.2,0.2,3,20,20);
  glRotatef(90,1,0,0);
  glTranslatef(0,3,0);
  twSolidCylinder(0.2,0.2,6,20,20);
  glPopMatrix();
}

//draws seat
void drawSeat() {
  glPushMatrix();
  twSolidCylinder(0.2,0.2,2,20,20); //post
  glRotatef(90,0,0,1);
  glScalef(0.5,1,1);                //flatten seat (y-direction)
  twSolidCylinder(1,0.2,2.5,20,20); //seat
  glPopMatrix();
}

//used three times in the bicycle, oriented downwards (y-direction)
void parallelBars(GLfloat length) {
  glPushMatrix();
  glTranslatef(0,0,0.5);
  twSolidCylinder(0.1,0.1,length,20,20);
  glTranslatef(0,0,-1);
  twSolidCylinder(0.1,0.1,length,20,20);
  //connect the bars
  glRotatef(-90,1,0,0);
  twSolidCylinder(0.1,0.1,1,20,20);
  glTranslatef(0,0,-length);
  twSolidCylinder(0.1,0.1,1,20,20);
  glPopMatrix();
}

void frame() {
  twColor(frameColor,0.9,100);
  //draw center bar
  glPushMatrix();
  glTranslatef(-5,0,0);
  glRotatef(90,0,0,1);
  twSolidCylinder(0.2,0.2,10,20,20); 
  glPopMatrix();
  //draw back frame
  glPushMatrix();
  glTranslatef(-5,0,0);
  GLfloat angle = atan(2.0/5.0)*180/M_PI;
  glRotatef(-angle,0,0,1);
  parallelBars(sqrt(29));
  glRotatef(angle*2,0,0,1);
  twSolidCylinder(0.2,0.2,sqrt(29),20,20);
  glPopMatrix();
  //draw front frame
  glPushMatrix();
  glTranslatef(5,0,0);
  glRotatef(angle,0,0,1);
  parallelBars(sqrt(29));
  GLfloat angle2 = atan(8.0/5.0)*180/M_PI;
  glRotatef(-angle2-angle,0,0,1);
  twSolidCylinder(0.2,0.2,sqrt(89),20,20);
  glPopMatrix();
}

void drawBicycle() {
 //draw back tire
  glPushMatrix();
  glTranslatef(-7,-5,0); 
  drawTire();
  twColor(frameColor,0.9,100); //return to frame color
  glRotatef(90,0,0,1);
  parallelBars(4);
  glPopMatrix();
  //draw front tire
  glPushMatrix();
  glTranslatef(6,-5,0);
  drawTire();
  glPopMatrix();
  //draw frame
  frame();
  //draw handlebars
  glPushMatrix();
  glTranslatef(5,3,0);
  drawHandlebar();
  glPopMatrix();
  //draw seat
  glPushMatrix();
  glTranslatef(-5,2,0);
  drawSeat();
  glPopMatrix();
}

twTriple rail [] =
{
  {0,0,0},
  {0.25,0,0},
  {0.25,0.2,0},
  {0,0.2,0}
};

void drawRail () {
    glBegin(GL_POLYGON);
    {
        glVertex3fv(rail[0]);
        glVertex3fv(rail[1]);
        glVertex3fv(rail[2]);
        glVertex3fv(rail[3]);
    }
    glEnd();
}

// Arbitrary numeric identifier for this call list.
#define PICKET 100
twTriple maroon = {0.5, 0, 0};

void drawInit() {
    /* Create a call list for one picket of the fence */
    glNewList(PICKET, GL_COMPILE);
    glPushMatrix();
    glScalef(0.225,1.3,0.1); 
    twSolidBarn(maroon, maroon, maroon);
    glPopMatrix();
    glPushMatrix();
    twColorName(TW_OLIVE);
    glTranslatef(-0.025,0.2,-0.05);
    drawRail();
    glTranslatef(0,0.5,0);
    drawRail();
    glPopMatrix();
    glEndList();
}

void display(void) {
    int i;
    twDisplayInit();
    glLineWidth(2);
    twCamera();
    sun();
    fog();

    // draw ground
    twTriple grassGreen = {0,0.3,0};
    twColor(grassGreen,0,0);
    //   twGround();
    glBegin(GL_POLYGON);
    glVertex3f(-6,0,-15);
    glVertex3f(-6,0,0);
    glVertex3f(6,0,0);
    glVertex3f(6,0,-15);
    glEnd();

    // draw front fence
    glPushMatrix();
    glTranslatef(-4,0,0);
    for(i=0;i<40;i++) {
        glCallList(PICKET);
        glTranslatef(0.25,0,0);
    }
    glPopMatrix();
  
    // draw right side fence
    glPushMatrix();
    glTranslatef(6,0,0);
    glRotatef(90,0,1,0); 
    for(i=0;i<55;i++) {
        glCallList(PICKET);
        glTranslatef(0.25,0,0);
    }
    glPopMatrix();
  
    // draw left side fence
    glPushMatrix();
    glTranslatef(-4,0,0);
    glRotatef(90,0,1,0);
    for(i=0;i<55;i++) {
        glCallList(PICKET);
        glTranslatef(0.25,0,0);
    }
    glPopMatrix();

    // draw barn
    glPushMatrix();
    glTranslatef(-2,0,-6);
    // glRotatef(-90,0,1,0);
    glScalef(3,4,5);
    twTriple darkBlue = {0,0,0.8};
    twTriple gray = {0.2,0.2,0.2};
    twSolidBarn(darkBlue, darkBlue, gray);
    glPopMatrix();

    //draw bicycle
    glPushMatrix();
    glTranslatef(0, 0.85, -11.2);
    //glRotatef(90,0,1,0);
    glScalef(0.1,0.1,0.1);
    drawBicycle();
    glPopMatrix();
    glFlush();
    glutSwapBuffers();
}

void fogToggle(unsigned char k, int, int) {
  FogOption = (FogOption+1)%3;
  glutPostRedisplay();
}

int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  twInitWindowSize(500,500);
  glutCreateWindow(argv[0]);
  drawInit();
  glutDisplayFunc(display);
  // the real are is -40,60 and -125,5
  twBoundingBox(-3,7,0,3,-9.5,0);//-45,65,0,65,-130,5);
  twMainInit(); 
  twKeyCallback('f',fogToggle,"switch among fog options");
  glutMainLoop();
  return 0;
}