/*  plot_lobatto.c  plot Lobatto and basis functions */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <GL/glut.h>
#include "lobatto_shape.h"

static GLfloat points[130][3];
static GLfloat colors[11][3] = {1.0, 0.0, 0.0,  0.0, 1.0, 0.0,  0.0, 0.0, 1.0,
                                1.0, 1.0, 0.0,  1.0, 0.0, 1.0,  0.0, 1.0, 1.0,
                                1.0, 0.5, 0.5,  0.5, 0.5, 1.0,  0.5, 1.0, 0.5,
                                0.7, 0.7, 0.7,  0.5, 0.5, 0.5};
static int n_points = 0;
static int n = 0;
static int width=800;
static int height=600;
static int np = 11;
static double xmin = -1.0;
static double xmax =  1.0;
static double ymin = 99.9;
static double ymax =-99.0;
static float offset = 0.0;
static int L_or_basis = 0;

void compute_basis(int i)
{
  double x, y, h;
  double z = 0.0;
  int j;

  n = 60;
  n_points = n;
  h = (xmax-xmin)/(double)(n-1);
  x = xmin;
  for(j=0; j<n; j++)
  {
    if(i==0) y = ph0(x);
    if(i==1) y = ph1(x);
    if(i==2) y = ph2(x);
    if(i==3) y = ph3(x);
    if(i==4) y = ph4(x);
    if(i==5) y = ph5(x);
    if(i==6) y = ph6(x);

    if(i==0 && j==0) {ymin=y; ymax=y;}
    if(y>ymax) ymax=y;
    if(y<ymin) ymin=y;
    points[j][0] = (float)1.5*x-1.0*xmin+offset;
    points[j][1] = (float)y+4.0;
    points[j][2] = (float)z;
    x = x+h;
  }
  printf("basis i=%d, ymin=%g, ymax=%g \n", i, ymin, ymax);
} /* end compute_basis */

void compute_lobatto(int i)
{
  double x, y, h;
  double z = 0.0;
  int j;

  n = 50;
  n_points = n;
  h = (xmax-xmin)/(double)(n-1);
  x = xmin;
  for(j=0; j<n; j++)
  {
    if(i==0) y = L2(x);
    if(i==1) y = L3(x);
    if(i==2) y = L4(x);
    if(i==3) y = L5(x);
    if(i==4) y = L6(x);
    if(i==5) y = L7(x);
    if(i==6) y = L8(x);
    if(i==0 && j==0) {ymin=y; ymax=y;}
    if(y>ymax) ymax=y;
    if(y<ymin) ymin=y;
    points[j][0] = (float)1.5*x-1.0*xmin+offset;
    points[j][1] = (float)y*4.0+4.0;
    points[j][2] = (float)z;
    x = x+h;
  }
  printf("lobatto i=%d, ymin=%g, ymax=%g \n", i, ymin, ymax);
} /* end compute_lobatto */


void draw_points(int i)
{
  int j;

  glColor3fv(colors[i]);
  for(j=0; j<n_points-1; j++)
  {
    glBegin(GL_LINES);
      glVertex3fv(points[j]);
      glVertex3fv(points[j+1]);
    glEnd();
  }
} /* end draw_points */

static void drawText(float x, float y, char * msg)
{
  int   i, len;

  glRasterPos2f(x, y);
  len = strlen(msg);
  for (i=0; i<len; i++)
    glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, msg[i]);
}

void display(void)
{
  char text1[]="L_i(x)  scaled Lobatto functions  xmin=-1.0  xmax=1.0  ";
  char text1y[]="ymin=dd.dd  ymax=dd.dd ";
  char text1b[]="ph_i(x)  basis functions  xmin=-1.0  xmax=1.0 ";
  char text2[]="i =   ";
  char text3[]="0";
  char text4[]="1";
  char text4m[]="-1";
  char num[6];
  int i, j;
  
  /* clear window */
  glClear(GL_COLOR_BUFFER_BIT); 
  glLoadIdentity ();
  glColor3f(0.0, 0.0, 0.0);
  
  if(L_or_basis==0)
  {
    /* draw title text */
    glColor3f(0.0, 0.0, 0.0);
    drawText(-0.95, -0.90, text1);
    drawText(-0.33 ,  3.9 , text3);
    drawText(-0.33 ,  7.2 , text4);
    drawText(-0.33 ,  0.6 , text4m);
    for(i=0; i<7; i++)
    {
      glColor3fv(colors[i]);
      text2[4] = (char)(48+i+2);
      drawText(-0.9, -0.20+i*0.6, text2);
    }
  }
  if(L_or_basis==1)
  {
    /* draw title text */
    glColor3f(0.0, 0.0, 0.0);
    drawText(-0.95, -0.90, text1b);
    drawText(-0.33 ,  3.9 , text3);
    drawText(-0.33 ,  4.6 , text4);
    drawText(-0.33 ,  3.2 , text4m);
    for(i=0; i<7; i++)
    {
      glColor3fv(colors[i]);
      text2[4] = (char)(48+i);
      drawText(-0.9, -0.20+i*0.6, text2);
    }
  }
  glColor3f(0.0, 0.0, 0.0);
  
  /* Draw the points */
  if(L_or_basis==1)
  {
    offset = 0.25;
    for(i=0; i<np; i++)
    {
      compute_basis(i);
      draw_points(i);
    }
  }
  if(L_or_basis==0)
  {
    offset = 0.25;
    for(i=0; i<np; i++)
    {
      compute_lobatto(i);
      draw_points(i);
    }
  }
  glColor3f(0.0, 0.0, 0.0);
  sprintf(num, "%5.2f", ymin);
  for(i=0; i<5; i++) text1y[i+5]=num[i];
  sprintf(num, "%5.2f", ymax);
  for(i=0; i<5; i++) text1y[i+17]=num[i];
  drawText(2.0, -0.90, text1y);

  glFlush(); 
}

/* This routine handels mouse events */
static void mouse(int button, int state, int x, int y)
{
  float wx, wy;
  if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
  {
    L_or_basis = 1-L_or_basis;
    ymin = 99.0;
    ymax = -99.0;
  }
  if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
  {
    L_or_basis = 1-L_or_basis;
    ymin = 99.0;
    ymax = -99.0;
  }
  glutPostRedisplay();
}

/* This routine handles window resizes */
void reshape(int w, int h)
{
  width = w;
  height = h;
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-1.0, 3.0, -1.0, 10.0, -1.0, 1.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glViewport(0, 0, w, h);
}

void init()
{
  /* set clear color to white */
  glClearColor (1.0, 1.0, 1.0, 0.0);
  /* set fill  color to black */
  glColor3f(0.0, 0.0, 0.0);
  /* Set the transformations */
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(-1.0, 3.0, -1.0, 10.0, -1.0, 1.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glViewport(0, 0, width, height);

}

int main(int argc, char* argv[])
{
  glutInit(&argc,argv);
  glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);  
  glutInitWindowSize(width, height);
  glutInitWindowPosition(0,0); 
  
  glutCreateWindow(argv[0]); 
  glutDisplayFunc(display);
  glutMouseFunc(mouse);
  init();
  glutMainLoop();
  return 0;
}