/* $Id: isosurf.c,v 3.0 1998/02/14 18:42:29 brianp Exp $ */

/*
 * Display an isosurface of 3-D wind speed volume.  Use arrow keys to
 * rotate, S toggles smooth shading, L toggles lighting
 * Brian Paul  This file in public domain.
 */

/*
 * $Log: isosurf.c,v $
 * Revision 3.0  1998/02/14 18:42:29  brianp
 * initial rev
 *
 */



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


GLboolean speed_test = GL_FALSE;
GLboolean use_vertex_arrays = GL_FALSE;

GLboolean doubleBuffer = GL_TRUE;

GLboolean smooth = GL_TRUE;
GLboolean lighting = GL_TRUE;



#define MAXVERTS 10000

static GLfloat verts[MAXVERTS][3];
static GLfloat norms[MAXVERTS][3];
static GLint numverts;

static GLfloat xrot;
static GLfloat yrot;



static void read_surface( char *filename )
{
   FILE *f;

   f = fopen(filename,"r");
   if (!f) {
      printf("couldn't read %s\n", filename);
      exit(1);
   }

   numverts = 0;
   while (!feof(f) && numverts<MAXVERTS) {
      fscanf( f, "%f %f %f  %f %f %f",
	      &verts[numverts][0], &verts[numverts][1], &verts[numverts][2],
	      &norms[numverts][0], &norms[numverts][1], &norms[numverts][2] );
      numverts++;
   }
   numverts--;

   printf("%d vertices, %d triangles\n", numverts, numverts-2);
   fclose(f);
}



static void draw_surface( void )
{
   GLuint i;

#ifdef GL_EXT_vertex_array
   if (use_vertex_arrays) {
      glDrawArraysEXT( GL_TRIANGLE_STRIP, 0, numverts );
   }
   else {
#endif
      glBegin( GL_TRIANGLE_STRIP );
      for (i=0;i<numverts;i++) {
	 glNormal3fv( norms[i] );
	 glVertex3fv( verts[i] );
      }
      glEnd();
#ifdef GL_EXT_vertex_array
   }
#endif
}



static void draw1(void)
{
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glPushMatrix();
    glRotatef( yrot, 0.0, 1.0, 0.0 );
    glRotatef( xrot, 1.0, 0.0, 0.0 );

    draw_surface();

    glPopMatrix();

    glFlush();
    if (doubleBuffer) {
	glutSwapBuffers();
    }
}


static void Draw(void)
{
   if (speed_test) {
      for (xrot=0.0;xrot<=360.0;xrot+=10.0) {
	 draw1();
      }
      exit(0);
   }
   else {
      draw1();
   }
}



static void InitMaterials(void)
{
    static float ambient[] = {0.1, 0.1, 0.1, 1.0};
    static float diffuse[] = {0.5, 1.0, 1.0, 1.0};
    static float position0[] = {0.0, 0.0, 20.0, 0.0};
    static float position1[] = {0.0, 0.0, -20.0, 0.0};
    static float front_mat_shininess[] = {60.0};
    static float front_mat_specular[] = {0.2, 0.2, 0.2, 1.0};
    static float front_mat_diffuse[] = {0.5, 0.28, 0.38, 1.0};
    /*
    static float back_mat_shininess[] = {60.0};
    static float back_mat_specular[] = {0.5, 0.5, 0.2, 1.0};
    static float back_mat_diffuse[] = {1.0, 1.0, 0.2, 1.0};
    */
    static float lmodel_ambient[] = {1.0, 1.0, 1.0, 1.0};
    static float lmodel_twoside[] = {(GLint)GL_FALSE};

    glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
    glLightfv(GL_LIGHT0, GL_POSITION, position0);
    glEnable(GL_LIGHT0);
    
    glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
    glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
    glLightfv(GL_LIGHT1, GL_POSITION, position1);
    glEnable(GL_LIGHT1);
    
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
    glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
    glEnable(GL_LIGHTING);

    glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_mat_shininess);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_mat_specular);
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, front_mat_diffuse);
}


static void Init(void)
{
   glClearColor(0.0, 0.0, 0.0, 0.0);

   glShadeModel(GL_SMOOTH);
   glEnable(GL_DEPTH_TEST);

   InitMaterials();

   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustum( -1.0, 1.0, -1.0, 1.0, 5, 25 );

   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef( 0.0, 0.0, -6.0 );

#ifdef GL_EXT_vertex_array
   if (use_vertex_arrays) {
      glVertexPointerEXT( 3, GL_FLOAT, 0, numverts, verts );
      glNormalPointerEXT( GL_FLOAT, 0, numverts, norms );
      glEnable( GL_VERTEX_ARRAY_EXT );
      glEnable( GL_NORMAL_ARRAY_EXT );
   }
#endif
}



static void Reshape(int width, int height)
{
    glViewport(0, 0, (GLint)width, (GLint)height);
}




static void Key( unsigned char key, int x, int y )
{
   switch (key) {
      case 27:
	 exit(0);
      case 's':
	smooth = !smooth;
	if (smooth) {
	    glShadeModel(GL_SMOOTH);
	} else {
	    glShadeModel(GL_FLAT);
	}
	break;
      case 'l':
	lighting = !lighting;
	if (lighting) {
	    glEnable(GL_LIGHTING);
	} else {
	    glDisable(GL_LIGHTING);
	}
	break;
   }
   glutPostRedisplay();
}


static void SpecialKey( int key, int x, int y )
{
   switch (key) {
      case GLUT_KEY_LEFT:
	yrot -= 15.0;
	break;
      case GLUT_KEY_RIGHT:
	yrot += 15.0;
	break;
      case GLUT_KEY_UP:
	xrot += 15.0;
	break;
      case GLUT_KEY_DOWN:
	xrot -= 15.0;
	break;
    }
    glutPostRedisplay();
}



static GLenum Args(int argc, char **argv)
{
   GLint i;

   for (i = 1; i < argc; i++) {
      if (strcmp(argv[i], "-sb") == 0) {
	 doubleBuffer = GL_FALSE;
      }
      else if (strcmp(argv[i], "-db") == 0) {
	 doubleBuffer = GL_TRUE;
      }
      else if (strcmp(argv[i], "-speed") == 0) {
	 speed_test = GL_TRUE;
	 doubleBuffer = GL_TRUE;
      }
      else if (strcmp(argv[i], "-va") == 0) {
	 use_vertex_arrays = GL_TRUE;
      }
      else {
	 printf("%s (Bad option).\n", argv[i]);
	 return GL_FALSE;
      }
   }

   return GL_TRUE;
}



int main(int argc, char **argv)
{
   GLenum type;
   char *extensions;

   read_surface( "isosurf.dat" );

   if (Args(argc, argv) == GL_FALSE) {
      exit(0);
   }

   glutInitWindowPosition(0, 0);
   glutInitWindowSize(400, 400);
   
   type = GLUT_DEPTH;
   type |= GLUT_RGB;
   type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
   glutInitDisplayMode(type);

   if (glutCreateWindow("Isosurface") <= 0) {
      exit(0);
   }

   /* Make sure server supports the vertex array extension */
   extensions = (char *) glGetString( GL_EXTENSIONS );
   if (!strstr( extensions, "GL_EXT_vertex_array" )) {
      use_vertex_arrays = GL_FALSE;
   }

   Init();

   glutReshapeFunc(Reshape);
   glutKeyboardFunc(Key);
   glutSpecialFunc(SpecialKey);
   glutDisplayFunc(Draw);
   glutMainLoop();
   return 0;
}