/* Demo of defining the front of a quadilateral for use in material and
   lighting.  This demo is similar to FrontBack, so look at the
   documentation for that one.

   The answer is that none of these flat quads looks "right".  You really
   have to draw the quad twice, so that you never have to deal with back
   facets.

Implemented Fall 2004
Scott D. Anderson
*/

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



twTriple Quad[4] = 
{
  {-1,-1,0},                        // left, bottom, front 
  {+1,-1,0},                        // right, bottom, front 
  {-1,+1,0},                        // left, top, front 
  {+1,+1,0},                        // right, top, front 
};

bool CullFace = false;
bool Amb = true;
bool Diff = true;
bool Spec = true;
bool LocalViewer = false;
bool TwoSided = false;
bool Back = true;

void drawQuad(int a, int b, int c, int d) {
    // twTriple N;
    // twPlaneNormal(N,Quad[a],Quad[b],Quad[c]);
    glBegin(GL_QUADS);
    // glNormal3f(N[0],N[1],N[2]);
    glVertex3fv(Quad[a]);
    glVertex3fv(Quad[b]);
    glVertex3fv(Quad[c]);
    glVertex3fv(Quad[d]);
    glEnd();
    glPushAttrib(GL_ALL_ATTRIB_BITS);
    glDisable(GL_LIGHTING);
    glColor3f(0,0,1);
    twDrawString(Quad[a][0],Quad[a][1],Quad[a][2],"A");
    twDrawString(Quad[b][0],Quad[b][1],Quad[b][2],"B");
    twDrawString(Quad[c][0],Quad[c][1],Quad[c][2],"C");
    twDrawString(Quad[d][0],Quad[d][1],Quad[d][2],"D");
    glPopAttrib();
}

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

    if(CullFace) {
        glEnable(GL_CULL_FACE);
    } else {
        glDisable(GL_CULL_FACE);
    }

    glEnable(GL_NORMALIZE);

    GLfloat lightDir[] = { -1, 0, 1, 0}; // from back right
    twGrayLight(GL_LIGHT0,lightDir,1,1,1);
    glEnable(GL_LIGHTING);

    if(LocalViewer) {
        glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,1);
    } else {
        glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,0);
    }

    if(TwoSided) {
        glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,1);
    } else {
        glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,0);
    }

    twTriple black = {0,0,0};
    twTriple red = {1,0,0};
    twTriple green = {0,1,0};
    twTriple blue = {0,0,1};
    twTriple yellow50 = {0.5,0.5,0};
    twTriple cyan50 = {0,0.5,0.5};
    twTriple magenta50 = {0.5,0,0.5};
    glMaterialfv(GL_FRONT,GL_AMBIENT,Amb?red:black);
    glMaterialfv(GL_FRONT,GL_DIFFUSE,Diff?green:black);
    glMaterialfv(GL_FRONT,GL_SPECULAR,Spec?blue:black);
    glMaterialf(GL_FRONT,GL_SHININESS,10);
    if(Back) {
        glMaterialfv(GL_BACK,GL_AMBIENT,Amb?magenta50:black);
        glMaterialfv(GL_BACK,GL_DIFFUSE,Diff?yellow50:black);
        glMaterialfv(GL_BACK,GL_SPECULAR,Spec?cyan50:black);
        glMaterialf(GL_BACK,GL_SHININESS,10);
    } else {
        glMaterialfv(GL_BACK,GL_AMBIENT,Amb?red:black);
        glMaterialfv(GL_BACK,GL_DIFFUSE,Diff?green:black);
        glMaterialfv(GL_BACK,GL_SPECULAR,Spec?blue:black);
        glMaterialf(GL_BACK,GL_SHININESS,10);
    }

    glutSolidSphere(1,32,32);

    // Upper right quad is proper:  CCW and N=(0,0,1);
    glPushMatrix();
    glTranslatef(+2,+2,0);
    glNormal3f(0,0,1);
    drawQuad(0,1,3,2);
    glPopMatrix();

    // Upper left quad is bad:  CW.  It disappears with backface culling
    glPushMatrix();
    glTranslatef(-2,+2,0);
    glNormal3f(0,0,1);
    drawQuad(0,2,3,1);
    glPopMatrix();

    // Lower left quad is bad: N=(0,0,-1).  It doesn't disappear with
    // backface culling, but we only see the ambient, not the
    // ambient+diffuse
    glPushMatrix();
    glTranslatef(-2,-2,0);
    glNormal3f(0,0,-1);
    drawQuad(0,1,3,2);
    glPopMatrix();

    // Lower right is a proper cube.  Looks just like the upper left
    glPushMatrix();
    glTranslatef(+2,-2,0);
    glScalef(2,2,0.1);
    glutSolidCube(1);
    glPopMatrix();

    glPushAttrib(GL_ALL_ATTRIB_BITS);
    glDisable(GL_LIGHTING);
    glColor3f(0,0,1);
    twDrawString(+2,+1.5,0,"CCW and normal=+z");
    twDrawString(-2,+1.5,0,"CW");
    twDrawString(-2,-2.5,0,"CCW, but normal=-z");
    twDrawString(+2,-2.5,1,"cube");

    twDrawString(0,-3.5,0,"TwoSide = %s",TwoSided?"on":"off");
    twDrawString(0,-3.7,0,"CullFace = %s",CullFace?"on":"off");
    twDrawString(0,-3.9,0,"LocalViewer = %s",LocalViewer?"on":"off");
    twDrawString(0,-4.1,0,"Ambient = %s",Amb?"on":"off");
    twDrawString(0,-4.3,0,"Diffuse = %s",Diff?"on":"off");
    twDrawString(0,-4.5,0,"Specular = %s",Spec?"on":"off");
    glPopAttrib();

    glFlush();
    glutSwapBuffers();
}


void keys(unsigned char k, int x, int y) {
    switch(k) {
    case 'a': Amb = !Amb; break;
    case 'd': Diff = !Diff; break;
    case 's': Spec = !Spec; break;
    case 'c': CullFace = !CullFace; break;
    case '1': { twTriple Y={0,1,0}; twRotateViewpoint(180,Y); } break;
    case 'l': LocalViewer = !LocalViewer; break;
    case '2': TwoSided = !TwoSided; break;
    case 'b': Back = !Back; break;
    case 'p': printf("\nAmbient %s\nDiffuse %s\nSpecular %s\nCullFace %s\nLocalViewer %s\nTwoSided %s\nBack Material %s\n",
                     Amb?"on":"off",
                     Diff?"on":"off",
                     Spec?"on":"off",
                     CullFace?"on":"off",
                     LocalViewer?"on":"off",
                     TwoSided?"on":"off",
                     Back?"on":"off");
        break;
    }
    glutPostRedisplay();
}

int main(int argc, char** argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  twInitWindowSize(500,600);
  glutCreateWindow(argv[0]);
  glutDisplayFunc(display);
  twBoundingBox(-2,+2,-2,+2,-1,+1); // a lie
  twMainInit();            
  twKeyCallback('c',keys,"toggle backface culling");
  twKeyCallback('a',keys,"toggle Ambient = red");
  twKeyCallback('d',keys,"toggle Diffuse = green");
  twKeyCallback('s',keys,"toggle Specular = blue");
  twKeyCallback('1',keys,"180 degree rotation");
  twKeyCallback('2',keys,"toggle two-sided lighting");
  twKeyCallback('l',keys,"toggle local viewer");
  twKeyCallback('b',keys,"toggle back material");
  twKeyCallback('p',keys,"print settings");
  glutMainLoop();
  return 0;
}