/* Demo of defining the front of a quadilateral for use in material and
   lighting.

Implemented Fall 2004
Scott D. Anderson
*/

#include <stdio.h>
#include <GL/glut.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();
}

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();

    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(500,500);
  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;
}