MOVELGHT.C

/* 
 * (c) Copyright 1993, Silicon Graphics, Inc. 
 *               1993-1995 Microsoft Corporation 
 * 
 * ALL RIGHTS RESERVED 
 * 
 * Please refer to OpenGL/readme.txt for additional information 
 * 
 */ 
 
/* 
 *  movelight.c 
 *  This program demonstrates when to issue lighting and  
 *  transformation commands to render a model with a light  
 *  which is moved by a modeling transformation (rotate or  
 *  translate).  The light position is reset after the modeling  
 *  transformation is called.  The eye position does not change. 
 * 
 *  A sphere is drawn using a grey material characteristic.  
 *  A single light source illuminates the object. 
 * 
 *  Interaction:  pressing the left or middle mouse button 
 *  alters the modeling transformation (x rotation) by 30 degrees.   
 *  The scene is then redrawn with the light in a new position. 
 */ 
#include "glos.h" 
 
#include <GL/gl.h> 
#include <GL/glu.h> 
#include <GL/glaux.h> 
 
void myinit(void); 
void CALLBACK movelight (AUX_EVENTREC *event); 
void CALLBACK display(void); 
void CALLBACK myReshape(GLsizei w, GLsizei h); 
 
static int spin = 0; 
 
void CALLBACK movelight (AUX_EVENTREC *event) 
{ 
    spin = (spin + 30) % 360; 
} 
 
void myinit (void) 
{ 
    glEnable(GL_LIGHTING); 
    glEnable(GL_LIGHT0); 
 
    glDepthFunc(GL_LESS); 
    glEnable(GL_DEPTH_TEST); 
} 
 
/*  Here is where the light position is reset after the modeling 
 *  transformation (glRotated) is called.  This places the  
 *  light at a new position in world coordinates.  The cube 
 *  represents the position of the light. 
 */ 
void CALLBACK display(void) 
{ 
    GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 }; 
 
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
    glPushMatrix (); 
    glTranslatef (0.0, 0.0, -5.0);  
 
    glPushMatrix (); 
    glRotated ((GLdouble) spin, 1.0, 0.0, 0.0); 
    glRotated (0.0, 1.0, 0.0, 0.0); 
    glLightfv (GL_LIGHT0, GL_POSITION, position); 
 
    glTranslated (0.0, 0.0, 1.5); 
    glDisable (GL_LIGHTING); 
    glColor3f (0.0, 1.0, 1.0); 
    auxWireCube (0.1); 
    glEnable (GL_LIGHTING); 
    glPopMatrix (); 
 
    auxSolidTorus (0.275, 0.85); 
    glPopMatrix (); 
    glFlush (); 
} 
 
void CALLBACK myReshape(GLsizei w, GLsizei h) 
{ 
    if (!h) return; 
    glViewport(0, 0, w, h); 
    glMatrixMode(GL_PROJECTION); 
    glLoadIdentity(); 
    gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0); 
    glMatrixMode(GL_MODELVIEW); 
} 
 
/*  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 ("Moving Light"); 
    myinit(); 
    auxMouseFunc (AUX_LEFTBUTTON, AUX_MOUSEDOWN, movelight); 
    auxReshapeFunc (myReshape); 
    auxMainLoop(display); 
    return(0); 
}