/* An open box, using material and lighting.  This is interesting because,
   depending on the angle of view, we will see either the "front" or
   "back" of different polygons, defining front as the counter-clockwise
   winding rule.  We'd like the lighting to look "right," so we'll use
   two-sided lighting and two-sided material.

   With two lights, that can be turned on/off independently.

   This demo thanks to Zsuzsa Moricz, class of 2006

Written by Scott D. Anderson
scott.anderson@acm.org
Fall 2005

*/

#include <stdio.h>
#include <tw.h>

void DrawQuadBothSides( twTriple vertexArray[], twTriple frontNormal, int a, int b, int c, int d) {
    glBegin(GL_QUADS);
    // frontwards
    glNormal3fv(frontNormal);
    glVertex3fv(vertexArray[a]);
    glVertex3fv(vertexArray[b]);
    glVertex3fv(vertexArray[c]);
    glVertex3fv(vertexArray[d]);
    // backwards
    glNormal3f(-frontNormal[0],
               -frontNormal[1],
               -frontNormal[2]);
    glVertex3fv(vertexArray[d]);
    glVertex3fv(vertexArray[c]);
    glVertex3fv(vertexArray[b]);
    glVertex3fv(vertexArray[a]);
    glEnd();
}

/* This box is a unit box, much like glutSolidCube, except that the
   vertices are 0/1, not -1/+1.  It uses whatever material you have
   specified, like glutSolidCube().  If you want something different,
   you'll have to scale it. */

void OpenBox() {
    GLfloat corners[][3] = {{ 0, 0, 0 }, // 0 lower left back
                            { 1, 0, 0 }, // 1 lower right back
                            { 1, 1, 0 }, // 2 upper right back
                            { 0, 1, 0 }, // 3 upper left back
                            { 0, 0, 1 }, // 4 lower left front
                            { 1, 0, 1 }, // 5 lower right front
                            { 1, 1, 1 }, // 6 upper right front
                            { 0, 1, 1 }}; // 7 upper left front

    GLfloat normals[][3] = {{ +1, 0, 0 }, // 0 right
                            { -1, 0, 0 }, // 1 left
                            { 0, +1, 0 }, // 2 up
                            { 0, -1, 0 }, // 3 down
                            { 0, 0, +1 }, // 4 towards
                            { 0, 0, -1 }}; // 5 away

    DrawQuadBothSides( corners, normals[0], 1, 2, 6, 5); // right
    DrawQuadBothSides( corners, normals[1], 0, 4, 7, 3); // left
    DrawQuadBothSides( corners, normals[2], 0, 4, 5, 1); // bottom
    DrawQuadBothSides( corners, normals[3], 4, 5, 6, 7); // front
    DrawQuadBothSides( corners, normals[4], 3, 2, 1, 0); // back
}

bool Light0 = true;
bool Light1 = true;

void display(void) {
    twDisplayInit();
    twCamera();
    glEnable(GL_LIGHTING);
    glEnable(GL_CULL_FACE);     // only draw front faces
    twAmbient(0.1);             // turn down ambient to make the
                                // lighting effects more obvious
    GLfloat light0[] = { 0, 2, 0, 1 };
    twGrayLight(GL_LIGHT0, light0, 0.1, 0.6, 0.7);
    if(Light0)
        glEnable(GL_LIGHT0);
    else
        glDisable(GL_LIGHT0);
    GLfloat light1[] = { 0, 2, 1, 0 };
    twGrayLight(GL_LIGHT1, light1, 0.1, 0.6, 0.8);
    if(Light1)
        glEnable(GL_LIGHT1);
    else
        glDisable(GL_LIGHT1);

    twTriple boxColor = {238/255.0, 197/255.0, 145/255.0};
    twColor(boxColor,0.4,10);

    OpenBox();

    glFlush();
    glutSwapBuffers();   // necessary for animation
}

void lightToggle(unsigned char k, int x, int y) {
    switch(k) {
    case '1': Light0 = !Light0; break;
    case '2': Light1 = !Light1; break;
    }
    glutPostRedisplay(); 
}

int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  twInitWindowSize(650,650);
  glutCreateWindow(argv[0]);
  twBoundingBox(-1,2,-1,2,-1,2);
  twMainInit(); 
  twKeyCallback('1', lightToggle, "Toggle first light");
  twKeyCallback('2', lightToggle, "Toggle second light");
  glutDisplayFunc(display);
  glutMainLoop();
  return 0;
}