/* A variation on the barn that has an error, so we can see how the
   gldebug flag works.

Implemented Fall 2003
Scott D. Anderson and Caroline Geiersbach
*/

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

const int barnWidth = 30;
const int barnHeight = 40;
const int barnLength = 50;

twTriple barn[10] = 
{
  {0,0,0},                                 //left, bottom, front 
  {barnWidth,0,0},                         // right, bottom, front 
  {barnWidth,barnHeight,0},                 // right, top, front 
  {0,barnHeight,0},                         // left, top, front 
  {barnWidth/2.0,barnHeight+barnWidth/2.0,0}, // ridge, front 
  {0,0,-barnLength},                     // left, bottom, back 
  {barnWidth,0,-barnLength},             // right, bottom, back 
  {barnWidth,barnHeight,-barnLength},    //right, top, back 
  {0,barnHeight,-barnLength},            // left, top, back 
  {barnWidth/2.0,barnHeight+barnWidth/2.0,-barnLength},// ridge, back 
};

// Almost every facet is a different color so that we can see them.

void drawBarn() {
    int i;
    twColorName(TW_RED);        // set color to red
    glBegin(GL_POLYGON);        // front 
    {
        glVertex3fv(barn[0]);
        glVertex3fv(barn[1]);
        glVertex3fv(barn[2]);
        glVertex3fv(barn[3]);
    }
    // ERROR:  here's a glBegin inside a glBegin
    glBegin(GL_POLYGON);        // front ridge 
    {
        glVertex3fv(barn[3]);
        glVertex3fv(barn[2]);
        glVertex3fv(barn[4]);
    }
    glEnd();
    glEnd();
    twColorName(TW_GREEN);
    glBegin(GL_POLYGON);        // back 
    {
        glVertex3fv(barn[5]);
        glVertex3fv(barn[6]);
        glVertex3fv(barn[7]);
        glVertex3fv(barn[8]);
    }
    glEnd();
    glBegin(GL_POLYGON);         // back ridge 
    {
        glVertex3fv(barn[7]);
        glVertex3fv(barn[8]);
        glVertex3fv(barn[9]);
    }
    glEnd();
    twColorName(TW_PURPLE);
    glBegin(GL_POLYGON);        // left side 
    {
      glVertex3fv(barn[0]);
      glVertex3fv(barn[3]);
      glVertex3fv(barn[8]);
      glVertex3fv(barn[5]);
    }
    glEnd();
    twColorName(TW_MAROON);
    glBegin(GL_POLYGON);        // right side 
    {
      glVertex3fv(barn[1]);
      glVertex3fv(barn[2]);
      glVertex3fv(barn[7]);
      glVertex3fv(barn[6]);
    }
    glEnd();
    twColorName(TW_OLIVE);
    glBegin(GL_POLYGON);        // left side roof 
    {
      glVertex3fv(barn[3]);
      glVertex3fv(barn[4]);
      glVertex3fv(barn[9]);
      glVertex3fv(barn[8]);
    }
    glEnd();
    glBegin(GL_POLYGON);        /* right side roof */
    {
      glVertex3fv(barn[2]);
      glVertex3fv(barn[4]);
      glVertex3fv(barn[9]);
      glVertex3fv(barn[7]);
    }
    glEnd();
}

void display(void) {
    twDisplayInit();
    twCamera();

    drawBarn();

    glFlush();
    glutSwapBuffers();
}

int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  twInitWindowSize(500,500);
  glutCreateWindow(argv[0]);
  glutDisplayFunc(display);
  twVertexArray(barn, 10); // determines dimensions of barn
  twMainInit();            
  glutMainLoop();
  return 0;
}