progs/tests/stencil_wrap.c

/*
 * (C) Copyright IBM Corporation 2004
 * All Rights Reserved.
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 * the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
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 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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 */

/**
 * \file stencil_wrap.c
 * 
 * Simple test of GL_EXT_stencil_wrap functionality.  Four squares are drawn
 * with different stencil modes, but all should be rendered with the same
 * final color.
 *
 * \author Ian Romanick <idr@us.ibm.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <GL/glew.h>
#include <GL/glut.h>

static int Width = 550;
static int Height = 200;
static const GLfloat Near = 5.0, Far = 25.0;


static void Display( void )
{
   GLint  max_stencil;
   GLint  stencil_bits;
   unsigned i;


   glGetIntegerv( GL_STENCIL_BITS, & stencil_bits );
   max_stencil = (1U << stencil_bits) - 1;
   printf( "Stencil bits = %u, maximum stencil value = 0x%08x\n",
	   stencil_bits, max_stencil );

   glClearStencil( 0 );
   glClearColor( 0.2, 0.2, 0.8, 0 );
   glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT 
	    | GL_STENCIL_BUFFER_BIT );


   glPushMatrix();

   /* This is the "reference" square.
    */

   glDisable(GL_STENCIL_TEST);
   glTranslatef(-6.0, 0, 0);
   glBegin(GL_QUADS);
   glColor3f( 0.5, 0.5, 0.5 );
   glVertex2f(-1, -1);
   glVertex2f( 1, -1);
   glVertex2f( 1,  1);
   glVertex2f(-1,  1);
   glEnd();


   glEnable(GL_STENCIL_TEST);

   /* Draw the first two squares using the two non-wrap (i.e., saturate)
    * modes.
    */

   glStencilFunc(GL_ALWAYS, 0, ~0);
   glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);

   glTranslatef(3.0, 0, 0);
   glBegin(GL_QUADS);
   glColor3f( 0.9, 0.9, 0.9 );

   for ( i = 0 ; i < (max_stencil + 5) ; i++ ) {
      glVertex2f(-1, -1);
      glVertex2f( 1, -1);
      glVertex2f( 1,  1);
      glVertex2f(-1,  1);
   }
   glEnd();

   glStencilFunc(GL_EQUAL, max_stencil, ~0);
   glBegin(GL_QUADS);
   glColor3f( 0.5, 0.5, 0.5 );
   glVertex2f(-1, -1);
   glVertex2f( 1, -1);
   glVertex2f( 1,  1);
   glVertex2f(-1,  1);
   glEnd();


   glStencilFunc(GL_ALWAYS, 0, ~0);
   glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);

   glTranslatef(3.0, 0, 0);
   glBegin(GL_QUADS);
   glColor3f( 0.9, 0.9, 0.9 );

   for ( i = 0 ; i < (max_stencil + 5) ; i++ ) {
      glVertex2f(-1, -1);
      glVertex2f( 1, -1);
      glVertex2f( 1,  1);
      glVertex2f(-1,  1);
   }
   glEnd();

   glStencilFunc(GL_EQUAL, 0, ~0);
   glBegin(GL_QUADS);
   glColor3f( 0.5, 0.5, 0.5 );
   glVertex2f(-1, -1);
   glVertex2f( 1, -1);
   glVertex2f( 1,  1);
   glVertex2f(-1,  1);
   glEnd();




   /* Draw the last two squares using the two wrap modes.
    */

   glStencilFunc(GL_ALWAYS, 0, ~0);
   glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP);

   glTranslatef(3.0, 0, 0);
   glBegin(GL_QUADS);
   glColor3f( 0.9, 0.9, 0.9 );

   for ( i = 0 ; i < (max_stencil + 5) ; i++ ) {
      glVertex2f(-1, -1);
      glVertex2f( 1, -1);
      glVertex2f( 1,  1);
      glVertex2f(-1,  1);
   }
   glEnd();

   glStencilFunc(GL_EQUAL, 4, ~0);
   glBegin(GL_QUADS);
   glColor3f( 0.5, 0.5, 0.5 );
   glVertex2f(-1, -1);
   glVertex2f( 1, -1);
   glVertex2f( 1,  1);
   glVertex2f(-1,  1);
   glEnd();


   
   glStencilFunc(GL_ALWAYS, 0, ~0);
   glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP);

   glTranslatef(3.0, 0, 0);
   glBegin(GL_QUADS);
   glColor3f( 0.9, 0.9, 0.9 );

   for ( i = 0 ; i < 5 ; i++ ) {
      glVertex2f(-1, -1);
      glVertex2f( 1, -1);
      glVertex2f( 1,  1);
      glVertex2f(-1,  1);
   }
   glEnd();

   glStencilFunc(GL_EQUAL, (max_stencil - 4), ~0);
   glBegin(GL_QUADS);
   glColor3f( 0.5, 0.5, 0.5 );
   glVertex2f(-1, -1);
   glVertex2f( 1, -1);
   glVertex2f( 1,  1);
   glVertex2f(-1,  1);
   glEnd();



   glPopMatrix();

   glutSwapBuffers();
}


static void Reshape( int width, int height )
{
   GLfloat ar = (float) width / (float) height;
   Width = width;
   Height = height;
   glViewport( 0, 0, width, height );
   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glFrustum( -ar, ar, -1.0, 1.0, Near, Far );
   glMatrixMode( GL_MODELVIEW );
   glLoadIdentity();
   glTranslatef( 0.0, 0.0, -15.0 );
}


static void Key( unsigned char key, int x, int y )
{
   (void) x;
   (void) y;
   switch (key) {
      case 27:
         exit(0);
         break;
   }
   glutPostRedisplay();
}


static void Init( void )
{
   const char * const ver_string = (const char * const)
       glGetString( GL_VERSION );

   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
   printf("GL_VERSION = %s\n", ver_string);

   if ( !glutExtensionSupported("GL_EXT_stencil_wrap") 
	&& (atof( ver_string ) < 1.4) ) {
      printf("Sorry, this program requires either GL_EXT_stencil_wrap or OpenGL 1.4.\n");
      exit(1);
   }

   printf("\nAll 5 squares should be the same color.\n");
   glEnable( GL_BLEND );
}


int main( int argc, char *argv[] )
{
   glutInit( &argc, argv );
   glutInitWindowPosition( 0, 0 );
   glutInitWindowSize( Width, Height );
   glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL );
   glutCreateWindow( "GL_EXT_stencil_wrap test" );
   glewInit();
   glutReshapeFunc( Reshape );
   glutKeyboardFunc( Key );
   glutDisplayFunc( Display );
   Init();
   glutMainLoop();
   return 0;
}