From octave-sources-request at bevo dot che dot wisc dot edu  Wed Sep  1 13:01:53 1999
Subject: Matlab equivalent of pcolor
From: jean-Marc Valin <jean-marc dot valin at hermes dot usherb dot ca>
To: octave-sources at bevo dot che dot wisc dot edu, octave-graphics@bevo.che.wisc.edu
Date: Wed, 01 Sep 1999 13:59:44 -0400

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Here (in attachment) is a function that works like Matlab
"pcolor" function. It calls (using popen2) a C executable.
To compile pcolor.c, you need OpenGL (or Mesa):

gcc -O2 -D_REENTRANT -o pcolor pcolor.c -L/usr/X11R6/lib -lMesaGL -lX11
-lXi -lpthread -lm

Also, tell me is you have any problem with the octave wrapper.

	Jean-Marc Valin

-- 
Jean-Marc Valin
Universite de Sherbrooke - Genie Electrique
valj01 at gel dot usherb dot ca

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// Copyright (C) 1999 Jean-Marc Valin
// modified from the 'glxdemo' sample Mesa program by Brian Paul
// 
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this file.  If not, write to the Free Software Foundation,
// 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <GL/gl.h>
#include <GL/glx.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <pthread.h>
#include <string.h>

/*#define redraw_funct redraw_interp*/

static int *table;
static float RGBMap[256][3];
int sizeX, sizeY;

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;


Window win;
Display *dpy;
pthread_t thread;
int exit_on_pipe_close;


void (*redraw_funct) ( Display *dpy, Window w);

void SetColor(int c)
{
   glColor3fv(RGBMap[c]);
   //glColor3f(RGBMap[c][0],RGBMap[c][1],RGBMap[c][2]);
}

void SetColorScale (int color)
{
   int i;
   pthread_mutex_lock (&mutex);
   if (color)
   { /* generate colorscale in color */
      for (i=0;i<64;i++)
      {
         RGBMap[i][0]=0.0;
         RGBMap[i][1]=i/64.0;
         RGBMap[i][2]=1.0;
      }
      for (i=64;i<128;i++)
      {
         RGBMap[i][0]=0.0;
         RGBMap[i][1]=1;
         RGBMap[i][2]=1-(i-64)/64.0;
      }
      for (i=128;i<184;i++)
      {
         RGBMap[i][0]=(i-128)/64.0;
         RGBMap[i][1]=1.0;
         RGBMap[i][2]=0;      
      }
      for (i=184;i<256;i++)
      {
         RGBMap[i][0]=1;
         RGBMap[i][1]=(1-(i-184)/64.0);
         RGBMap[i][2]=0;      
      }
      
   } else { /* generate colorscale in black and white */
      for (i=0;i<256;i++)
         RGBMap[i][0]=RGBMap[i][1]=RGBMap[i][2]=1.0-i/255.0;
   }

   pthread_mutex_unlock (&mutex);
}

/* Drawing routine for interpolation shading */
static void redraw_interp( Display *dpy, Window w )
{
   int width, height;
   int i,j;
   float top, bot, left, right;

   pthread_mutex_lock (&mutex);

   glClear( GL_COLOR_BUFFER_BIT );

   for (i=0;i<sizeX-1;i++)
    for (j=0;j<sizeY-1;j++)
      {
         bot = 1.6*j/(sizeY-1) - .8;
         top = 1.6*(j+1)/(sizeY-1) - .8;
         left = 1.6*i/(sizeX-1) - .8;
         right = 1.6*(i+1)/(sizeX-1) - .8;


         glBegin(GL_POLYGON);

         SetColor(table[i*sizeY+j]);
         glVertex2f(left, bot);

         SetColor(table[(i+1)*sizeY+j]);
         glVertex2f(right, bot);

         SetColor(table[(i+1)*sizeY+j+1]);
         glVertex2f(right, top);

         SetColor(table[i*sizeY+j+1]);
         glVertex2f(left, top);

         glEnd();
         
      }

   pthread_mutex_unlock (&mutex);
   
   glFlush();


   glXSwapBuffers( dpy, w );
}

/* Drawing routine for flat shading */
static void redraw_flat( Display *dpy, Window w )
{
   int width, height;
   int i,j;
   float top, bot, left, right;

   pthread_mutex_lock (&mutex);

   glClear( GL_COLOR_BUFFER_BIT );

   for (i=0;i<sizeX;i++)
    for (j=0;j<sizeY;j++)
      {
         bot = 1.6*j/(sizeY) - .8;
         top = 1.6*(j+1)/(sizeY) - .8;
         left = 1.6*i/(sizeX) - .8;
         right = 1.6*(i+1)/(sizeX) - .8;


         glBegin(GL_POLYGON);

         SetColor(table[i*sizeY+j]);
         glVertex2f(left, bot);

         glVertex2f(right, bot);

         glVertex2f(right, top);

         glVertex2f(left, top);

         glEnd();
         
      }

   pthread_mutex_unlock (&mutex);
   
   glFlush();


   glXSwapBuffers( dpy, w );
}

void SetShading (int interp)
{
   pthread_mutex_lock (&mutex);
   if (interp)
   {
      glShadeModel( GL_SMOOTH );
      redraw_funct = redraw_interp;
   } else {
      glShadeModel( GL_FLAT );
      redraw_funct = redraw_flat;
   }
   pthread_mutex_unlock (&mutex);

}


static void resize( unsigned int width, unsigned int height )
{
   glViewport( 0, 0, width, height );
   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
}



static Window make_rgb_db_window( Display *dpy,
				  unsigned int width, unsigned int height )
{
   int attrib[] = { GLX_RGBA,
		    GLX_RED_SIZE, 1,
		    GLX_GREEN_SIZE, 1,
		    GLX_BLUE_SIZE, 1,
		    GLX_DOUBLEBUFFER,
		    None };
   int scrnum;
   XSetWindowAttributes attr;
   unsigned long mask;
   Window root;
   Window win;
   GLXContext ctx;
   XVisualInfo *visinfo;

   scrnum = DefaultScreen( dpy );
   root = RootWindow( dpy, scrnum );

   visinfo = glXChooseVisual( dpy, scrnum, attrib );
   if (!visinfo) {
      printf("Error: couldn't get an RGB, Double-buffered visual\n");
      exit(1);
   }

   /* window attributes */
   attr.background_pixel = 0;
   attr.border_pixel = 0;
   attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
   attr.event_mask = StructureNotifyMask | ExposureMask;
   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;

   win = XCreateWindow( dpy, root, 0, 0, width, height,
		        0, visinfo->depth, InputOutput,
		        visinfo->visual, mask, &attr );

   ctx = glXCreateContext( dpy, visinfo, NULL, True );

   glXMakeCurrent( dpy, win, ctx );

   return win;
}


static void event_loop( Display *dpy )
{
   XEvent event;

   while (1) {
      XNextEvent( dpy, &event );

      switch (event.type) {
	 case Expose:
	    redraw_funct( dpy, event.xany.window );
	    break;
	 case ConfigureNotify:
	    resize( event.xconfigure.width, event.xconfigure.height );
	    break;
      }
   }
}

void change_data(void)
{
      int i,j;
      int sx, sy;
      float *table_float;
      int *table_int;
      float ratio, min=FLT_MAX, max=-FLT_MAX;
      scanf ("%d %d",&sx, &sy); 
      /*printf ("%d %d\n",sx, sy);*/
      table_float = malloc (sx*sy*sizeof(float));
      table_int = malloc (sx*sy*sizeof(int));
      for (i=0;i<sx;i++)
         for (j=0;j<sy;j++)
         {
            float tmp;
            scanf ("%f",&tmp);
            if (tmp > max) max = tmp;
            if (tmp < min) min = tmp;
            table_float[i*sy+j] = tmp;
         }
      ratio = 254.99/(max-min);
      for (i=0;i<sx*sy;i++)
      {
         table_int[i]=floor ((table_float[i]-min)*ratio);
      }
      free (table_float);

      pthread_mutex_lock(&mutex);
      
      free (table);
      table = table_int;
      sizeX=sx;
      sizeY=sy;
      pthread_mutex_unlock(&mutex);


}

void change_shading(void)
{
   char command[200];
   scanf ("%s",command);
   if (strcmp(command, "INTERP")==0)
      SetShading(1);
   else if (strcmp(command, "FLAT")==0)
      SetShading(0);
}

void change_colorscale(void)
{
   char command[200];
   scanf ("%s",command);
   if (strcmp(command, "COLOR")==0)
      SetColorScale(1);
   else if (strcmp(command, "BW")==0)
      SetColorScale(0);
}

void pipe_eof(void)
{
   if (!exit_on_pipe_close)
      pthread_join (thread, NULL);
   exit(0);
}


void update_loop(void)
{
   while (1)
   {
      char command[200];
      scanf ("%s",command);
      if (feof(stdin)) pipe_eof();
      if (strcmp(command, "DATA")==0)
         change_data();
      else if (strcmp(command, "SHADING")==0)
         change_shading();
      else if (strcmp(command, "COLORSCALE")==0)
         change_colorscale();
      else if (strcmp(command, "NOPIPEEXIT")==0)
         exit_on_pipe_close = 0;
      else if (strcmp(command, "PIPEEXIT")==0)
         exit_on_pipe_close = 1;
      else if (strcmp(command, "EXIT")==0)
         exit(0);
      else if (strcmp(command, "QUIT")==0)
         exit(0);
      else
         fprintf (stderr, "UNKNOWN COMMAND: \"%s\"\n", command);
      XLockDisplay(dpy);
      redraw_funct( dpy, win);
      XUnlockDisplay(dpy);
      if (feof(stdin)) pipe_eof();
   }
}

int init (void)
{
   int i,j;
   exit_on_pipe_close=1;
   sizeX=2;
   sizeY=2;
   table = malloc(sizeX*sizeY*sizeof(int));

   for (i=0;i<sizeX;i++)
      for (j=0;j<sizeY;j++)
         table[i*sizeY+j]=0;
   SetShading(1);
   SetColorScale(1);
   XInitThreads();
   dpy = XOpenDisplay(NULL);
   win = make_rgb_db_window( dpy, 300, 300 );
   glClearColor( 0.5, 0.5, 0.5, 1.0 );

   XMapWindow( dpy, win );
}

int main( int argc, char *argv[] )
{
   init();

   pthread_create(&thread, NULL, (void *(*)(void *)) event_loop, dpy);

   update_loop();

   return 0;
}

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## Copyright (C) 1999  Jean-Marc Valin
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this file.  If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

## usage:  xmensurewin(callsubplot)
##
## Matlab equivalent to pcolor
## Uses OpenGL to display 2D graphic

## Author:  Jean-Marc Valin <valj01 at gel dot usherb dot ca>

function pcolor(x)

global pcolor_pipe;
global pcolor_pid;

if !exist("pcolor_pipe")
     pcolor_pipe=0;
end


if (pcolor_pipe == 0)
   [pcolor_pipe,dummy,pcolor_pid] = popen2 ("pcolor","");
else
   [PID, MSG] = waitpid (pcolor_pid, 1);
   #printf ("received PID %d, MSG %s, pid=%d\n", PID, MSG, pcolor_pid);
   if (PID < 0)
      [pcolor_pipe,dummy,pcolor_pid] = popen2 ("pcolor","");
   end
end

#fprintf (pcolor_pipe, "COLORSCALE BW\n");
fprintf (pcolor_pipe, "DATA\n");
fprintf (pcolor_pipe, "%d %d\n", size(x,1), size(x,2));
fprintf (pcolor_pipe, "%g ", x);
fprintf (pcolor_pipe, "\n");
fflush (pcolor_pipe);

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