/* NURB curve (1-dimension)

Written by Caroline Geiersbach and Scott D. Anderson
scott.anderson@acm.org
Summer 2003
*/

#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include <math.h>
#include "tw.h"

//for picking
int count;
int p;
//number of points the user wants
int numPoints;

GLUnurbsObj *myNurb;
int uOrder; //cubic polynomial
int numKnots;

//specify all control points here
twTriple points[15] = {
  {-7,-3,1}, {-6,-3,1}, {-5,0,1}, {-4,-5,1}, {-3,5,1}, {-2,-3,1},
  {-1,3,1},{0,-16,1}, {1,0,1},{2,-3,1}, {3,-10,1}, {4,13,1},{5,-10,1},
  {6,-3,1},{7,-4,1},
};

//adapted from Hill pg. 635
void makeKnots(int ord, int pts, GLfloat knot[]) {
  //pts control points and B-splines of order ord
  int i;
  if(pts < ord) { 
    printf("too few control points entered for curve of order %i\n",uOrder);
    return; 
  }
  for (i=0; i<pts+ord; i++) {
    if (i<ord) knot[i]=0.0;
    else if (i<pts) knot[i] = i-ord+1; //i at least ord
    else knot[i] = pts-ord+1; //i exceeds pts
  }
}

void display(void) {
    int i;
    glClearColor(1,1,1,1);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    twCamera();
   
    numKnots = uOrder+numPoints;
    GLfloat uKnot[numKnots];
    makeKnots(uOrder,numPoints,uKnot);

    twColorName(TW_ORANGE);
    glLineWidth(3);
    gluBeginCurve(myNurb);
    /*gluNurbsCurve(GLUnurbsObj *myNurb, GLint uKnotCount, GLfloat *uKnot,
     GLint uStride, GLfloat *points, GLint uOrder(degree+1), GLenum type)*/
    gluNurbsCurve(myNurb,numKnots,uKnot,3,&points[0][0],uOrder,
                  GL_MAP1_VERTEX_3);
    gluEndCurve(myNurb);
 
    twColorName(TW_GRAY);
    glLineWidth(1);
    glBegin(GL_LINE_STRIP); //lines between points
    for(i=0;i<numPoints;i++) {
      glVertex3fv(points[i]);
    }
    glEnd();

    twColorName(TW_BLACK);
    glPointSize(3);
    glBegin(GL_POINTS);     //points
    for(i=0;i<numPoints;i++) {
      glVertex3fv(points[i]);
    }
    glEnd();
    
    glFlush();
    glutSwapBuffers(); 
}


//returns the array element num; otherwise 15
int testClick(int x, int y) {
  int i;
  twTriple screen, world;
  for(i = 0; i<numPoints; i++) {
    twTripleCopy(world,points[i]); 
    twProject(screen,world); //project world coords to screen
    if(x<screen[0]+4 && x>screen[0]-4 && y<screen[1]+4 && y>screen[1]-4) 
      return i;
  }
  return 15;
}

void pick(int x, int y, int element) {
  if(p<15) {
    twTriple world; //new coords for element
    twTriple A,B,V; 
    twTriple winA = {x,y,0}; 
    twTriple winB = {x,y,1}; 
    twUnProject(A,winA);
    twUnProject(B,winB);
    twVector(V,B,A);
    twPointOnLine(points[element],A,V,0.5);
  }
}

static int mouse_x, mouse_y;

void myMouse(int button, int state, int x, int y) {
  y=650-y;
  if(button==GLUT_LEFT_BUTTON && state==GLUT_DOWN){
    mouse_x=x;
    mouse_y=y;
    p = testClick(x,y);
  }
}

void myMotion(int x, int y) {
  y=650-y;
  pick(x,y,p);
  glutPostRedisplay();
}

void printCoords(unsigned char key, int x, int y) {
  int i;
  printf("Your current control points are: \n");
  for(i=0; i<numPoints; i++) {
    printf("control point %i",i);
    twTriplePrint("", points[i]);
  }
}

void keyInit() {
  twKeyCallback('p', printCoords, "prints values of control points");
}

void myInit() {
  twMainInit();
  glutMouseFunc(myMouse);
  glutMotionFunc(myMotion);
  keyInit();
  myNurb=gluNewNurbsRenderer();
  gluNurbsProperty(myNurb,GLU_DISPLAY_MODE,GLU_FILL);
  glEnable(GL_MAP1_VERTEX_3);
}

int main(int argc, char **argv) {
    printf("Enter the number of control points, up to 15 points\n");
    scanf("%i", &numPoints);
    printf("Enter the order of the curve\n");
    scanf("%i", &uOrder);
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(650, 650);
    twBoundingBox(-10,10,-10,10,-10,10);
    glutCreateWindow("NURBS!");
    glutDisplayFunc(display);
    myInit();
    glutMainLoop();
    return 0;
}