From afb833d4e89c312460a4ab9ed6a7a8ca4ebbfe1c Mon Sep 17 00:00:00 2001
From: jtg <jtg>
Date: Thu, 19 Aug 1999 00:55:39 +0000
Subject: Initial revision

---
 progs/demos/isosurf.c | 821 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 821 insertions(+)
 create mode 100644 progs/demos/isosurf.c

(limited to 'progs/demos/isosurf.c')

diff --git a/progs/demos/isosurf.c b/progs/demos/isosurf.c
new file mode 100644
index 0000000000..393197f66d
--- /dev/null
+++ b/progs/demos/isosurf.c
@@ -0,0 +1,821 @@
+/* $Id: isosurf.c,v 1.1 1999/08/19 00:55:40 jtg 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 1.1  1999/08/19 00:55:40  jtg
+ * Initial revision
+ *
+ * Revision 3.4  1999/04/24 01:10:47  keithw
+ * clip planes, materials
+ *
+ * Revision 3.3  1999/03/31 19:42:14  keithw
+ * support for cva
+ *
+ * Revision 3.1  1998/11/01 20:30:20  brianp
+ * added benchmark feature (b key)
+ *
+ * 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"
+
+#include "../util/readtex.c"   /* I know, this is a hack.  KW: me too. */
+#define TEXTURE_FILE "../images/reflect.rgb"
+
+#define LIT                 0x1
+#define UNLIT               0x2
+#define TEXTURE             0x4
+#define NO_TEXTURE          0x8
+#define REFLECT             0x10
+#define NO_REFLECT          0x20
+#define POINT_FILTER        0x40
+#define LINEAR_FILTER       0x80
+#define IMMEDIATE           0x100
+#define DRAW_ARRAYS         0x200 /* or draw_elts, if compiled */
+#define ARRAY_ELT           0x400
+#define COMPILED            0x800
+#define NOT_COMPILED        0x1000
+#define SHADE_SMOOTH        0x2000
+#define SHADE_FLAT          0x4000
+#define TRIANGLES           0x8000
+#define STRIPS              0x10000
+#define USER_CLIP           0x20000
+#define NO_USER_CLIP        0x40000
+#define MATERIALS           0x80000
+#define NO_MATERIALS        0x100000
+#define QUIT                0x800000
+
+#define LIGHT_MASK  (LIT|UNLIT)
+#define TEXTURE_MASK (TEXTURE|NO_TEXTURE)
+#define REFLECT_MASK (REFLECT|NO_REFLECT)
+#define FILTER_MASK (POINT_FILTER|LINEAR_FILTER)
+#define RENDER_STYLE_MASK (IMMEDIATE|DRAW_ARRAYS|ARRAY_ELT)
+#define COMPILED_MASK (COMPILED|NOT_COMPILED)
+#define MATERIAL_MASK (MATERIALS|NO_MATERIALS)
+#define PRIMITIVE_MASK (TRIANGLES|STRIPS)
+#define CLIP_MASK (USER_CLIP|NO_USER_CLIP)
+#define SHADE_MASK (SHADE_SMOOTH|SHADE_FLAT)
+
+#define MAXVERTS 10000
+static float data[MAXVERTS][6];
+static float compressed_data[MAXVERTS][6];
+static GLuint indices[MAXVERTS];
+static GLuint tri_indices[MAXVERTS*3];
+static GLfloat col[100][4];
+static GLint numverts, num_tri_verts, numuniq;
+
+static GLfloat xrot;
+static GLfloat yrot;
+static GLint state, allowed = ~0;
+static GLboolean doubleBuffer = GL_TRUE;
+static GLdouble plane[4] = {1.0, 0.0, -1.0, 0.0};
+
+
+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",
+	      &data[numverts][0], &data[numverts][1], &data[numverts][2],
+	      &data[numverts][3], &data[numverts][4], &data[numverts][5] );
+      numverts++;
+   }
+   numverts--;
+
+   printf("%d vertices, %d triangles\n", numverts, numverts-2);
+   fclose(f);
+}
+
+
+
+
+struct data_idx {
+   float *data;
+   int idx;
+   int uniq_idx;
+};
+
+
+#define COMPARE_FUNC( AXIS )                            \
+int compare_axis_##AXIS( const void *a, const void *b )	\
+{							\
+   float t = ( (*(struct data_idx *)a).data[AXIS] -	\
+	       (*(struct data_idx *)b).data[AXIS] );	\
+   							\
+   if (t < 0) return -1;				\
+   if (t > 0) return 1;					\
+   return 0;						\
+}
+
+COMPARE_FUNC(0)
+COMPARE_FUNC(1)
+COMPARE_FUNC(2)
+COMPARE_FUNC(3)
+COMPARE_FUNC(4)
+COMPARE_FUNC(5)
+COMPARE_FUNC(6)
+
+int (*(compare[7]))( const void *a, const void *b ) =
+{
+   compare_axis_0,
+   compare_axis_1,
+   compare_axis_2,
+   compare_axis_3,
+   compare_axis_4,
+   compare_axis_5,
+   compare_axis_6,
+};
+
+
+#define VEC_ELT(f, s, i)  (float *)(((char *)f) + s * i)
+
+static int sort_axis( int axis, 
+		      int vec_size,
+		      int vec_stride,
+		      struct data_idx *indices,
+		      int start,
+		      int finish,
+		      float *out,
+		      int uniq,
+		      const float fudge )
+{
+   int i;
+
+   if (finish-start > 2) 
+   {
+      qsort( indices+start, finish-start, sizeof(*indices), compare[axis] );
+   } 
+   else if (indices[start].data[axis] > indices[start+1].data[axis]) 
+   {
+      struct data_idx tmp = indices[start];
+      indices[start] = indices[start+1];
+      indices[start+1] = tmp;
+   }
+	 
+   if (axis == vec_size-1) {
+      for (i = start ; i < finish ; ) {
+	 float max = indices[i].data[axis] + fudge;
+	 float *dest = VEC_ELT(out, vec_stride, uniq);
+	 int j;
+	
+	 for (j = 0 ; j < vec_size ; j++)
+	    dest[j] = indices[i].data[j];
+
+	 for ( ; i < finish && max >= indices[i].data[axis]; i++) 
+	    indices[i].uniq_idx = uniq;
+
+	 uniq++;
+      }
+   } else {
+      for (i = start ; i < finish ; ) {
+	 int j = i + 1;
+	 float max = indices[i].data[axis] + fudge;
+	 while (j < finish && max >= indices[j].data[axis]) j++;
+	 if (j == i+1) {
+	    float *dest = VEC_ELT(out, vec_stride, uniq);
+	    int k;
+
+	    indices[i].uniq_idx = uniq;
+	
+	    for (k = 0 ; k < vec_size ; k++)
+	       dest[k] = indices[i].data[k];
+
+	    uniq++;
+	 } else {
+	    uniq = sort_axis( axis+1, vec_size, vec_stride,
+			      indices, i, j, out, uniq, fudge );
+	 }
+	 i = j;
+      }
+   }
+
+   return uniq;
+}
+
+
+static void extract_indices1( const struct data_idx *in, unsigned int *out, 
+			      int n )
+{
+   int i;
+   for ( i = 0 ; i < n ; i++ ) {
+      out[in[i].idx] = in[i].uniq_idx;
+   }
+}
+
+
+static void compactify_arrays()
+{
+   int i;
+   struct data_idx *ind;
+
+   ind = (struct data_idx *) malloc( sizeof(struct data_idx) * numverts );
+
+   for (i = 0 ; i < numverts ; i++) {
+      ind[i].idx = i;
+      ind[i].data = data[i];
+   }
+
+   numuniq = sort_axis(0, 
+		       sizeof(compressed_data[0])/sizeof(float), 
+		       sizeof(compressed_data[0]),
+		       ind, 
+		       0, 
+		       numverts, 
+		       (float *)compressed_data, 
+		       0,
+		       1e-6);
+
+   printf("Nr unique vertex/normal pairs: %d\n", numuniq);
+
+   extract_indices1( ind, indices, numverts );
+   free( ind );
+}
+
+static float myrand( float max )
+{
+   return max*rand()/(RAND_MAX+1.0);
+}
+
+
+static void make_tri_indices( void )
+{
+   unsigned int *v = tri_indices;
+   unsigned int parity = 0;
+   unsigned int i, j;
+
+   for (j=2;j<numverts;j++,parity^=1) {
+      if (parity) {
+	 *v++ = indices[j-1];
+	 *v++ = indices[j-2]; 
+	 *v++ = indices[j];
+      } else {
+	 *v++ = indices[j-2];
+	 *v++ = indices[j-1];
+	 *v++ = indices[j];
+      }
+   }
+   
+   num_tri_verts = v - tri_indices;
+   printf("num_tri_verts: %d\n", num_tri_verts);
+
+   for (i = j = 0 ; i < num_tri_verts ; i += 600, j++) {
+      col[j][3] = 1;
+      col[j][2] = myrand(1);
+      col[j][1] = myrand(1);
+      col[j][0] = myrand(1);
+   }
+}
+
+#define MIN(x,y) (x < y) ? x : y
+
+static void draw_surface( void )
+{
+   GLuint i, j;
+
+   switch (state & (COMPILED_MASK|RENDER_STYLE_MASK|PRIMITIVE_MASK)) {
+#ifdef GL_EXT_vertex_array
+
+   case (COMPILED|DRAW_ARRAYS|STRIPS):
+      glDrawElements( GL_TRIANGLE_STRIP, numverts, GL_UNSIGNED_INT, indices );
+      break;
+
+
+   case (COMPILED|ARRAY_ELT|STRIPS):
+      glBegin( GL_TRIANGLE_STRIP );
+      for (i = 0 ; i < numverts ; i++) 
+	 glArrayElement( indices[i] );      
+      glEnd();
+      break;
+
+   case (COMPILED|DRAW_ARRAYS|TRIANGLES):
+   case (NOT_COMPILED|DRAW_ARRAYS|TRIANGLES):
+      if (state & MATERIALS) {
+	 for (j = i = 0 ; i < num_tri_verts ; i += 600, j++) {
+	    GLuint nr = MIN(num_tri_verts-i, 600);
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, col[j]);
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, col[j]);
+	    glDrawElements( GL_TRIANGLES, nr, GL_UNSIGNED_INT, tri_indices+i );
+	 }
+      } else {
+	 glDrawElements( GL_TRIANGLES, num_tri_verts, GL_UNSIGNED_INT, 
+			 tri_indices );
+      }
+
+      break;
+
+      /* Uses the original arrays (including duplicate elements):
+       */
+   case (NOT_COMPILED|DRAW_ARRAYS|STRIPS):
+      glDrawArraysEXT( GL_TRIANGLE_STRIP, 0, numverts );
+      break;
+
+      /* Uses the original arrays (including duplicate elements):
+       */
+   case (NOT_COMPILED|ARRAY_ELT|STRIPS):
+      glBegin( GL_TRIANGLE_STRIP );
+      for (i = 0 ; i < numverts ; i++)
+	 glArrayElement( i );
+      glEnd();
+      break;
+
+   case (NOT_COMPILED|ARRAY_ELT|TRIANGLES):
+   case (COMPILED|ARRAY_ELT|TRIANGLES):
+      if (state & MATERIALS) {
+	 for (j = i = 0 ; i < num_tri_verts ; i += 600, j++) {
+	    GLuint nr = MIN(num_tri_verts-i, 600);
+	    GLuint k;
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, col[j]);
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, col[j]);
+	    glBegin( GL_TRIANGLES );
+	    for (k = 0 ; k < nr ; k++)
+	       glArrayElement( tri_indices[i+k] );
+	    glEnd();
+	 }
+      } else {
+	 glBegin( GL_TRIANGLES );
+	 for (i = 0 ; i < num_tri_verts ; i++)
+	    glArrayElement( tri_indices[i] );
+	 glEnd();
+      }	 
+      break;
+
+   case (NOT_COMPILED|IMMEDIATE|TRIANGLES):
+      if (state & MATERIALS) {
+	 for (j = i = 0 ; i < num_tri_verts ; i += 600, j++) {
+	    GLuint nr = MIN(num_tri_verts-i, 600);
+	    GLuint k;
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, col[j]);
+	    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, col[j]);
+	    glBegin( GL_TRIANGLES );
+	    for (k = 0 ; k < nr ; k++) {
+	       glNormal3fv( &compressed_data[tri_indices[i+k]][3] );
+	       glVertex3fv( &compressed_data[tri_indices[i+k]][0] );
+	    }
+	    glEnd();
+	 }
+      } else {
+	 glBegin( GL_TRIANGLES );
+	 for (i = 0 ; i < num_tri_verts ; i++) {
+	    glNormal3fv( &compressed_data[tri_indices[i]][3] );
+	    glVertex3fv( &compressed_data[tri_indices[i]][0] );
+	 }
+	 glEnd();
+      }	 
+      break;
+
+#endif
+
+      /* Uses the original arrays (including duplicate elements):
+       */
+   default:
+      glBegin( GL_TRIANGLE_STRIP );
+      for (i=0;i<numverts;i++) {
+         glNormal3fv( &data[i][3] );
+         glVertex3fv( &data[i][0] );
+      }
+      glEnd();
+   }
+}
+
+
+
+static void Display(void)
+{
+    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
+    draw_surface();
+    glFlush();
+    if (doubleBuffer) glutSwapBuffers();    
+}
+
+/* KW: only do this when necessary, so CVA can re-use results.
+ */
+static void set_matrix( void )
+{
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+   glTranslatef( 0.0, 0.0, -6.0 );
+   glRotatef( yrot, 0.0, 1.0, 0.0 );
+   glRotatef( xrot, 1.0, 0.0, 0.0 );
+}
+
+static void Benchmark( float xdiff, float ydiff )
+{
+   int startTime, endTime;
+   int draws;
+   double seconds, fps, triPerSecond;
+
+   printf("Benchmarking...\n");
+
+   draws = 0;
+   startTime = glutGet(GLUT_ELAPSED_TIME);
+   xrot = 0.0;
+   do {
+      xrot += xdiff;
+      yrot += ydiff;
+      set_matrix();
+      Display();
+      draws++;
+      endTime = glutGet(GLUT_ELAPSED_TIME);
+   } while (endTime - startTime < 5000);   /* 5 seconds */
+
+   /* Results */
+   seconds = (double) (endTime - startTime) / 1000.0;
+   triPerSecond = (numverts - 2) * draws / seconds;
+   fps = draws / seconds;
+   printf("Result:  triangles/sec: %g  fps: %g\n", triPerSecond, fps);
+}
+
+
+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[] = {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);
+
+    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);
+}
+
+
+
+#define UPDATE(o,n,mask) (o&=~mask, o|=n&mask)
+#define CHANGED(o,n,mask) ((n&mask) && \
+                           (n&mask) != (o&mask) ? UPDATE(o,n,mask) : 0)
+
+static void ModeMenu(int m)
+{
+   m &= allowed;
+
+   if (!m) return;
+
+   if (m==QUIT) 
+      exit(0);
+
+   if (CHANGED(state, m, FILTER_MASK)) {
+      if (m & LINEAR_FILTER) {
+	 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+      } else {
+	 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+      }
+   }
+
+   if (CHANGED(state, m, LIGHT_MASK)) {
+      if (m & LIT)
+	 glEnable(GL_LIGHTING);
+      else
+	 glDisable(GL_LIGHTING);
+   }
+
+   if (CHANGED(state, m, SHADE_MASK)) {
+      if (m & SHADE_SMOOTH)
+	 glShadeModel(GL_SMOOTH);
+      else
+	 glShadeModel(GL_FLAT);
+   }
+
+
+   if (CHANGED(state, m, TEXTURE_MASK)) {
+      if (m & TEXTURE) 
+	 glEnable(GL_TEXTURE_2D);
+      else
+	 glDisable(GL_TEXTURE_2D);
+   }
+
+   if (CHANGED(state, m, REFLECT_MASK)) {
+      if (m & REFLECT) {
+	 glEnable(GL_TEXTURE_GEN_S);
+	 glEnable(GL_TEXTURE_GEN_T);
+      } else {
+	 glDisable(GL_TEXTURE_GEN_S);
+	 glDisable(GL_TEXTURE_GEN_T);
+      }
+   }
+
+   if (CHANGED(state, m, CLIP_MASK)) {
+      if (m & USER_CLIP) {
+	 glEnable(GL_CLIP_PLANE0);
+      } else {
+	 glDisable(GL_CLIP_PLANE0);
+      }
+   }
+
+#ifdef GL_EXT_vertex_array
+   if (CHANGED(state, m, (COMPILED_MASK|RENDER_STYLE_MASK|PRIMITIVE_MASK))) 
+   {
+      if ((m & (COMPILED_MASK|PRIMITIVE_MASK)) == (NOT_COMPILED|STRIPS))
+      {
+	 glVertexPointerEXT( 3, GL_FLOAT, sizeof(data[0]), numverts, data );
+	 glNormalPointerEXT( GL_FLOAT, sizeof(data[0]), numverts, &data[0][3]);
+      }
+      else 
+      {
+	 glVertexPointerEXT( 3, GL_FLOAT, sizeof(data[0]), numuniq, 
+			     compressed_data );
+	 glNormalPointerEXT( GL_FLOAT, sizeof(data[0]), numuniq, 
+			     &compressed_data[0][3]);
+      }
+#ifdef GL_EXT_compiled_vertex_array
+      if (m & COMPILED) {
+	 glLockArraysEXT( 0, numuniq );
+      } else {
+	 glUnlockArraysEXT();
+      }
+#endif
+   }
+#endif
+
+   if (m & (RENDER_STYLE_MASK|PRIMITIVE_MASK)) {
+      UPDATE(state, m, (RENDER_STYLE_MASK|PRIMITIVE_MASK));
+   }
+   
+   if (m & MATERIAL_MASK) {
+      UPDATE(state, m, MATERIAL_MASK);
+   }
+
+   glutPostRedisplay();
+}
+
+
+
+static void Init(void)
+{
+   glClearColor(0.0, 0.0, 0.0, 0.0);
+   glEnable( GL_DEPTH_TEST );
+   glEnable( GL_VERTEX_ARRAY_EXT );
+   glEnable( GL_NORMAL_ARRAY_EXT );
+
+   InitMaterials();
+
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glFrustum( -1.0, 1.0, -1.0, 1.0, 5, 25 );
+
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+   glClipPlane(GL_CLIP_PLANE0, plane); 
+
+   set_matrix();
+
+   glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
+   glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
+
+   glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
+   glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
+
+   if (!LoadRGBMipmaps(TEXTURE_FILE, GL_RGB)) {
+      printf("Error: couldn't load texture image\n");
+      exit(1);
+   }
+
+   if (allowed & COMPILED) {
+      compactify_arrays();
+      make_tri_indices();
+   }
+
+   ModeMenu(SHADE_SMOOTH|
+	    LIT|
+	    NO_TEXTURE|
+	    NO_REFLECT|
+	    POINT_FILTER|
+	    NOT_COMPILED|
+	    NO_USER_CLIP|
+	    NO_MATERIALS|
+	    IMMEDIATE);
+}
+
+
+
+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':
+	 ModeMenu((state ^ SHADE_MASK) & SHADE_MASK);
+         break;
+      case 'l':
+	 ModeMenu((state ^ LIGHT_MASK) & LIGHT_MASK);
+         break;
+      case 'm':
+	 ModeMenu((state ^ MATERIAL_MASK) & MATERIAL_MASK);
+         break;
+      case 'c':
+	 ModeMenu((state ^ CLIP_MASK) & CLIP_MASK);
+         break;
+      case 'b':
+         Benchmark(5.0, 0);
+         break;
+      case 'B':
+         Benchmark(0, 5.0);
+         break;
+      case '-':
+      case '_':
+	plane[3] += 2.0;
+	glMatrixMode(GL_MODELVIEW);
+	glLoadIdentity();
+	glClipPlane(GL_CLIP_PLANE0, plane);
+	set_matrix();
+	glutPostRedisplay();
+	break;
+      case '+':
+      case '=':
+	plane[3] -= 2.0;
+	glMatrixMode(GL_MODELVIEW);
+	glLoadIdentity();
+	glClipPlane(GL_CLIP_PLANE0, plane);
+	set_matrix();
+	glutPostRedisplay();
+	break;
+
+   }
+}
+
+
+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;
+   default:
+      return;
+   }
+   set_matrix();
+   glutPostRedisplay();
+}
+
+
+
+static GLint Args(int argc, char **argv)
+{
+   GLint i;
+   GLint mode = 0;
+
+   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 {
+         printf("%s (Bad option).\n", argv[i]);
+	 return QUIT;
+      }
+   }
+
+   return mode;
+}
+
+int main(int argc, char **argv)
+{
+   GLenum type;
+   char *extensions;
+
+   GLuint arg_mode = Args(argc, argv);
+
+   if (arg_mode & QUIT)
+      exit(0);
+
+   read_surface( "isosurf.dat" );
+
+   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" )) 
+   {
+      printf("Vertex arrays not supported by this renderer\n");
+      allowed &= ~(COMPILED|DRAW_ARRAYS|ARRAY_ELT);
+   }
+   else if (!strstr( extensions, "GL_EXT_compiled_vertex_array" )) 
+   {
+      printf("Compiled vertex arrays not supported by this renderer\n");
+      allowed &= ~COMPILED;
+   }
+
+   Init();
+   ModeMenu(arg_mode);
+   
+   glutCreateMenu(ModeMenu);
+   glutAddMenuEntry("Lit",                   LIT|NO_TEXTURE|NO_REFLECT);
+   glutAddMenuEntry("Unlit",                 UNLIT|NO_TEXTURE|NO_REFLECT);
+/*    glutAddMenuEntry("Textured", TEXTURE); */
+   glutAddMenuEntry("Reflect",               TEXTURE|REFLECT);
+   glutAddMenuEntry("", 0);   
+   glutAddMenuEntry("Smooth",                SHADE_SMOOTH);
+   glutAddMenuEntry("Flat",                  SHADE_FLAT);
+   glutAddMenuEntry("", 0);   
+   glutAddMenuEntry("Point Filtered",        POINT_FILTER);
+   glutAddMenuEntry("Linear Filtered",       LINEAR_FILTER);
+   glutAddMenuEntry("", 0);   
+   glutAddMenuEntry("Immediate (STRIPS)",    NOT_COMPILED|IMMEDIATE|STRIPS);
+   glutAddMenuEntry("Immediate (TRIANGLES)", NOT_COMPILED|IMMEDIATE|TRIANGLES);
+   glutAddMenuEntry("", 0);   
+   if (allowed & DRAW_ARRAYS) {
+      glutAddMenuEntry("DrawArrays (STRIPS)",
+		       NOT_COMPILED|DRAW_ARRAYS|STRIPS);
+      glutAddMenuEntry("ArrayElement (STRIPS)",  
+		       NOT_COMPILED|ARRAY_ELT|STRIPS);
+      glutAddMenuEntry("DrawElements (TRIANGLES)", 
+		       NOT_COMPILED|DRAW_ARRAYS|TRIANGLES);
+      glutAddMenuEntry("ArrayElement (TRIANGLES)", 
+		       NOT_COMPILED|ARRAY_ELT|TRIANGLES);
+      glutAddMenuEntry("", 0);   
+
+   }
+   if (allowed & COMPILED) {
+      glutAddMenuEntry("Compiled DrawElements (TRIANGLES)", 
+		       COMPILED|DRAW_ARRAYS|TRIANGLES);
+      glutAddMenuEntry("Compiled DrawElements (STRIPS)", 
+		       COMPILED|DRAW_ARRAYS|STRIPS);
+      glutAddMenuEntry("Compiled ArrayElement", 
+		       COMPILED|ARRAY_ELT|STRIPS);   
+      glutAddMenuEntry("", 0);   
+   }
+   glutAddMenuEntry("Quit",                  QUIT);
+   glutAttachMenu(GLUT_RIGHT_BUTTON);
+
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutSpecialFunc(SpecialKey);
+   glutDisplayFunc(Display);
+   glutMainLoop();
+   return 0;
+}
-- 
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