/* Demo of the classic barn object.  This uses two helper functions that
   improve the abstraction and brevity of the code.

Implemented Fall 2007
Scott D. Anderson
*/

#include <stdio.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 
};

void drawTri(twTriple verts[],int a, int b, int c) {
    glBegin(GL_TRIANGLES);
    glVertex3fv(verts[a]);
    glVertex3fv(verts[b]);
    glVertex3fv(verts[c]);
    glEnd();
}

void drawQuad(twTriple verts[],int a, int b, int c, int d) {
    glBegin(GL_QUADS);
    glVertex3fv(verts[a]);
    glVertex3fv(verts[b]);
    glVertex3fv(verts[c]);
    glVertex3fv(verts[d]);
    glEnd();
}

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

void drawBarn() {
    twColorName(TW_RED);        // set color to red
    drawQuad(barn,0,1,2,3);     // front
    drawTri(barn,3,2,4);
    twColorName(TW_GREEN);
    drawQuad(barn,5,6,7,8);     // back
    drawTri(barn,7,8,9);
    twColorName(TW_PURPLE);
    drawQuad(barn,0,3,8,5);     // left side
    twColorName(TW_MAROON);
    drawQuad(barn,1,2,7,6);     // right side
    twColorName(TW_OLIVE);
    drawQuad(barn,3,4,9,8);     // left roof
    drawQuad(barn,2,4,9,7);     // right roof

    twError();                  // check for errors after a sequence of
                                // geometric primitives
}

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;
}