FOGINDEX.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/* 
 *  fogindex.c 
 *  This program demonstrates fog in color index mode.   
 *  Three cones are drawn at different z values in a linear  
 *  fog.  32 contiguous colors (from 16 to 47) are loaded  
 *  with a color ramp. 
 */ 
#include "glos.h" 
 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glaux.h> 
 
void myinit(void); 
void CALLBACK myReshape(GLsizei w, GLsizei h); 
void CALLBACK display(void); 
 
/*  Initialize color map and fog.  Set screen clear color 
 *  to end of color ramp. 
 */ 
#define NMCOLORS 32 
#define RAMPSTART 16 
 
void myinit(void) 
{ 
    int i; 
 
    glEnable(GL_DEPTH_TEST); 
    glDepthFunc(GL_LESS); 
    for (i = 0; i < NMCOLORS; i++) { 
    GLfloat shade; 
    shade = (GLfloat) (NMCOLORS-i)/(GLfloat) NMCOLORS; 
    auxSetOneColor (16 + i, shade, shade, shade); 
    } 
    glEnable(GL_FOG); 
 
    glFogi (GL_FOG_MODE, GL_LINEAR); 
    glFogi (GL_FOG_INDEX, NMCOLORS); 
    glFogf (GL_FOG_START, 0.0); 
    glFogf (GL_FOG_END, 4.0); 
    glHint (GL_FOG_HINT, GL_NICEST); 
    glClearIndex((GLfloat) (NMCOLORS+RAMPSTART-1)); 
} 
 
/*  display() renders 3 cones at different z positions. 
 */ 
void CALLBACK display(void) 
{ 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glPushMatrix (); 
    glTranslatef (-1.0, -1.0, -1.0); 
    glRotatef (-90.0, 1.0, 0.0, 0.0); 
    glIndexi (RAMPSTART); 
    auxSolidCone(1.0, 2.0); 
    glPopMatrix (); 
 
    glPushMatrix (); 
    glTranslatef (0.0, -1.0, -2.25); 
    glRotatef (-90.0, 1.0, 0.0, 0.0); 
    glIndexi (RAMPSTART); 
    auxSolidCone(1.0, 2.0); 
    glPopMatrix (); 
 
    glPushMatrix (); 
    glTranslatef (1.0, -1.0, -3.5); 
    glRotatef (-90.0, 1.0, 0.0, 0.0); 
    glIndexi (RAMPSTART); 
    auxSolidCone(1.0, 2.0); 
    glPopMatrix (); 
    glFlush(); 
} 
 
void CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if (!h) return; 
    glViewport(0, 0, w, h); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    if (w <= h) 
    glOrtho (-2.0, 2.0, -2.0*(GLfloat)h/(GLfloat)w,  
        2.0*(GLfloat)h/(GLfloat)w, 0.0, 10.0); 
    else 
    glOrtho (-2.0*(GLfloat)w/(GLfloat)h,  
        2.0*(GLfloat)w/(GLfloat)h, -2.0, 2.0, 0.0, 10.0); 
    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity (); 
} 
 
/*  Main Loop 
 *  Open window with initial window size, title bar,  
 *  RGBA display mode, depth buffer, and handle input events. 
 */ 
int main(int argc, char** argv) 
{ 
    auxInitDisplayMode (AUX_SINGLE | AUX_INDEX | AUX_DEPTH16); 
    auxInitPosition (0, 0, 200, 200); 
    auxInitWindow ("Fog Using Color Index"); 
    myinit(); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}