ALPHA3D.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/* 
 *  alpha3D.c 
 *  This program demonstrates how to intermix opaque and 
 *  alpha blended polygons in the same scene, by using glDepthMask. 
 *  Pressing the left mouse button toggles the eye position. 
 */ 
#include "glos.h" 
 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glaux.h> 
 
void myinit(void); 
void CALLBACK toggleEye (AUX_EVENTREC *event); 
void CALLBACK myReshape(GLsizei w, GLsizei h); 
void CALLBACK display(void); 
 
void myinit(void) 
{ 
    GLfloat mat_ambient[] = { 0.0, 0.0, 0.0, 0.15 }; 
    GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 0.15 }; 
    GLfloat mat_shininess[] = { 15.0 }; 
 
    glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient); 
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); 
    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess); 
 
    glEnable (GL_LIGHTING); 
    glEnable (GL_LIGHT0); 
    glDepthFunc(GL_LESS); 
    glEnable(GL_DEPTH_TEST); 
} 
 
GLboolean eyePosition = GL_FALSE; 
 
void CALLBACK toggleEye (AUX_EVENTREC *event) 
{ 
    if (eyePosition) 
    eyePosition = GL_FALSE; 
    else 
    eyePosition = GL_TRUE; 
} 
 
void CALLBACK display(void) 
{ 
    GLfloat position[] = { 0.0, 0.0, 1.0, 1.0 }; 
    GLfloat mat_torus[] = { 0.75, 0.75, 0.0, 1.0 }; 
    GLfloat mat_cylinder[] = { 0.0, 0.75, 0.75, 0.15 }; 
 
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glLightfv (GL_LIGHT0, GL_POSITION, position); 
    glPushMatrix (); 
    if (eyePosition) 
        gluLookAt (0.0, 0.0, 9.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);  
    else  
        gluLookAt (0.0, 0.0, -9.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);  
    glPushMatrix (); 
    glTranslatef (0.0, 0.0, 1.0);     
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_torus); 
    auxSolidTorus (0.275, 0.85); 
    glPopMatrix (); 
 
    glEnable (GL_BLEND); 
    glDepthMask (GL_FALSE); 
    glBlendFunc (GL_SRC_ALPHA, GL_ONE); 
    glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_cylinder); 
    glTranslatef (0.0, 0.0, -1.0);     
    auxSolidCylinder (1.0, 2.0); 
    glDepthMask (GL_TRUE); 
    glDisable (GL_BLEND); 
    glPopMatrix (); 
 
    glFlush (); 
} 
 
void CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if(!h) return; 
    glViewport(0, 0, w, h); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    gluPerspective(30.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0); 
    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity(); 
} 
 
/*  Main Loop 
 *  Open window with initial window size, title bar,  
 *  RGBA display mode, and handle input events. 
 */ 
int main(int argc, char** argv) 
{ 
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB | AUX_DEPTH16); 
    auxInitPosition (0, 0, 500, 500); 
    auxInitWindow ("Intermixing Opaque and Alpha Blending"); 
    auxMouseFunc (AUX_LEFTBUTTON, AUX_MOUSEDOWN, toggleEye); 
    myinit(); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}