/* $Id: reflect.c,v 3.0 1998/02/14 18:42:29 brianp Exp $ */
/*
* Demo of a reflective, texture-mapped surface with OpenGL.
* Brian Paul August 14, 1995 This file is in the public domain.
*
* Hardware texture mapping is highly recommended!
*
* The basic steps are:
* 1. Render the reflective object (a polygon) from the normal viewpoint,
* setting the stencil planes = 1.
* 2. Render the scene from a special viewpoint: the viewpoint which
* is on the opposite side of the reflective plane. Only draw where
* stencil = 1. This draws the objects in the reflective surface.
* 3. Render the scene from the original viewpoint. This draws the
* objects in the normal fashion. Use blending when drawing
* the reflective, textured surface.
*
* This is a very crude demo. It could be much better.
*/
/*
* Dirk Reiners (reiners@igd.fhg.de) made some modifications to this code.
*
* August 1996 - A few optimizations by Brian
*/
/*
* April, 1997 - Added Mark Kilgard's changes.
*/
/*
* $Log: reflect.c,v $
* Revision 3.0 1998/02/14 18:42:29 brianp
* initial rev
*
*/
#define USE_ZBUFFER
/* OK, without hardware support this is overkill. */
#define USE_TEXTURE
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "GL/glut.h"
#include "../util/readtex.c" /* a hack, I know */
#define DEG2RAD (3.14159/180.0)
#define TABLE_TEXTURE "reflect.rgb"
static int ImgWidth, ImgHeight;
static GLenum ImgFormat;
static GLubyte *Image = NULL;
#define MAX_OBJECTS 2
static GLint table_list;
static GLint objects_list[MAX_OBJECTS];
static GLfloat xrot, yrot;
static GLfloat spin;
static void make_table( void )
{
static GLfloat table_mat[] = { 1.0, 1.0, 1.0, 0.6 };
static GLfloat gray[] = { 0.4, 0.4, 0.4, 1.0 };
table_list = glGenLists(1);
glNewList( table_list, GL_COMPILE );
/* load table's texture */
glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, table_mat );
/* glMaterialfv( GL_FRONT, GL_EMISSION, gray );*/
glMaterialfv( GL_FRONT, GL_DIFFUSE, table_mat );
glMaterialfv( GL_FRONT, GL_AMBIENT, gray );
/* draw textured square for the table */
glPushMatrix();
glScalef( 4.0, 4.0, 4.0 );
glBegin( GL_POLYGON );
glNormal3f( 0.0, 1.0, 0.0 );
glTexCoord2f( 0.0, 0.0 ); glVertex3f( -1.0, 0.0, 1.0 );
glTexCoord2f( 1.0, 0.0 ); glVertex3f( 1.0, 0.0, 1.0 );
glTexCoord2f( 1.0, 1.0 ); glVertex3f( 1.0, 0.0, -1.0 );
glTexCoord2f( 0.0, 1.0 ); glVertex3f( -1.0, 0.0, -1.0 );
glEnd();
glPopMatrix();
glDisable( GL_TEXTURE_2D );
glEndList();
}
static void make_objects( void )
{
GLUquadricObj *q;
static GLfloat cyan[] = { 0.0, 1.0, 1.0, 1.0 };
static GLfloat green[] = { 0.2, 1.0, 0.2, 1.0 };
static GLfloat black[] = { 0.0, 0.0, 0.0, 0.0 };
q = gluNewQuadric();
gluQuadricDrawStyle( q, GLU_FILL );
gluQuadricNormals( q, GLU_SMOOTH );
objects_list[0] = glGenLists(1);
glNewList( objects_list[0], GL_COMPILE );
glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, cyan );
glMaterialfv( GL_FRONT, GL_EMISSION, black );
gluCylinder( q, 0.5, 0.5, 1.0, 15, 10 );
glEndList();
objects_list[1] = glGenLists(1);
glNewList( objects_list[1], GL_COMPILE );
glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green );
glMaterialfv( GL_FRONT, GL_EMISSION, black );
gluCylinder( q, 1.5, 0.0, 2.5, 15, 10 );
glEndList();
}
static GLfloat light_pos[] = { 0.0, 20.0, 0.0, 1.0 };
static void init( void )
{
make_table();
make_objects();
/* Setup texture */
#ifdef USE_TEXTURE
Image = LoadRGBImage( TABLE_TEXTURE, &ImgWidth, &ImgHeight, &ImgFormat );
if (!Image) {
printf("Couldn't read %s\n", TABLE_TEXTURE);
exit(0);
}
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, ImgWidth, ImgHeight,
ImgFormat, GL_UNSIGNED_BYTE, Image);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
#endif
xrot = 30.0;
yrot = 50.0;
spin = 0.0;
#ifndef USE_ZBUFFER
glEnable( GL_CULL_FACE );
#endif
glShadeModel( GL_FLAT );
glEnable( GL_LIGHT0 );
glEnable( GL_LIGHTING );
glClearColor( 0.5, 0.5, 0.5, 1.0 );
glEnable( GL_NORMALIZE );
}
static void reshape(int w, int h)
{
GLfloat aspect = (float) w / (float) h;
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum( -aspect, aspect, -1.0, 1.0, 4.0, 300.0 );
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
static void draw_objects( GLfloat eyex, GLfloat eyey, GLfloat eyez )
{
#ifndef USE_ZBUFFER
if (eyex<0.5)
{
#endif
glPushMatrix();
glTranslatef( 1.0, 1.5, 0.0 );
glRotatef( spin, 1.0, 0.5, 0.0 );
glRotatef( 0.5*spin, 0.0, 0.5, 1.0 );
glCallList( objects_list[0] );
glPopMatrix();
glPushMatrix();
glTranslatef( -1.0, 0.85+3.0*fabs( cos(0.01*spin) ), 0.0 );
glRotatef( 0.5*spin, 0.0, 0.5, 1.0 );
glRotatef( spin, 1.0, 0.5, 0.0 );
glScalef( 0.5, 0.5, 0.5 );
glCallList( objects_list[1] );
glPopMatrix();
#ifndef USE_ZBUFFER
}
else
{
glPushMatrix();
glTranslatef( -1.0, 0.85+3.0*fabs( cos(0.01*spin) ), 0.0 );
glRotatef( 0.5*spin, 0.0, 0.5, 1.0 );
glRotatef( spin, 1.0, 0.5, 0.0 );
glScalef( 0.5, 0.5, 0.5 );
glCallList( objects_list[1] );
glPopMatrix();
glPushMatrix();
glTranslatef( 1.0, 1.5, 0.0 );
glRotatef( spin, 1.0, 0.5, 0.0 );
glRotatef( 0.5*spin, 0.0, 0.5, 1.0 );
glCallList( objects_list[0] );
glPopMatrix();
}
#endif
}
static void draw_table( void )
{
glCallList( table_list );
}
static void draw_scene( void )
{
GLfloat dist = 20.0;
GLfloat eyex, eyey, eyez;
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
eyex = dist * cos(yrot*DEG2RAD) * cos(xrot*DEG2RAD);
eyez = dist * sin(yrot*DEG2RAD) * cos(xrot*DEG2RAD);
eyey = dist * sin(xrot*DEG2RAD);
/* view from top */
glPushMatrix();
gluLookAt( eyex, eyey, eyez, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0 );
glLightfv( GL_LIGHT0, GL_POSITION, light_pos );
/* draw table into stencil planes */
glEnable( GL_STENCIL_TEST );
#ifdef USE_ZBUFFER
glDisable( GL_DEPTH_TEST );
#endif
glStencilFunc( GL_ALWAYS, 1, 0xffffffff );
glStencilOp( GL_REPLACE, GL_REPLACE, GL_REPLACE );
glColorMask( GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE );
draw_table();
glColorMask( GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE );
#ifdef USE_ZBUFFER
glEnable( GL_DEPTH_TEST );
#endif
/* render view from below (reflected viewport) */
/* only draw where stencil==1 */
if (eyey>0.0) {
glPushMatrix();
glStencilFunc( GL_EQUAL, 1, 0xffffffff ); /* draw if ==1 */
glStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );
glScalef( 1.0, -1.0, 1.0 );
/* Reposition light in reflected space. */
glLightfv(GL_LIGHT0, GL_POSITION, light_pos);
draw_objects(eyex, eyey, eyez);
glPopMatrix();
/* Restore light's original unreflected position. */
glLightfv(GL_LIGHT0, GL_POSITION, light_pos);
}
glDisable( GL_STENCIL_TEST );
glEnable( GL_BLEND );
glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
#ifdef USE_TEXTURE
glEnable( GL_TEXTURE_2D );
#endif
draw_table();
glDisable( GL_TEXTURE_2D );
glDisable( GL_BLEND );
/* view from top */
glPushMatrix();
draw_objects(eyex, eyey, eyez);
glPopMatrix();
glPopMatrix();
glutSwapBuffers();
}
#if 0
void draw_scene(void)
{
GLfloat dist = 20.0;
GLfloat eyex, eyey, eyez;
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
eyex = dist * cos(yrot*DEG2RAD) * cos(xrot*DEG2RAD);
eyez = dist * sin(yrot*DEG2RAD) * cos(xrot*DEG2RAD);
eyey = dist * sin(xrot*DEG2RAD);
/* view from top */
glPushMatrix();
gluLookAt( eyex, eyey, eyez, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0 );
draw_table();
glPopMatrix();
glutSwapBuffers();
}
#endif
static void Key( unsigned char key, int x, int y )
{
if (key==27)
exit(0);
}
static void SpecialKey( int key, int x, int y )
{
switch (key) {
case GLUT_KEY_UP:
xrot += 3.0;
#ifndef USE_ZBUFFER
if ( xrot > 180 ) xrot = 180;
#endif
break;
case GLUT_KEY_DOWN:
xrot -= 3.0;
#ifndef USE_ZBUFFER
if ( xrot < 0 ) xrot = 0;
#endif
break;
case GLUT_KEY_LEFT:
yrot += 3.0;
break;
case GLUT_KEY_RIGHT:
yrot -= 3.0;
break;
}
glutPostRedisplay();
}
static void idle( void )
{
spin += 2.0;
yrot += 3.0;
glutPostRedisplay();
}
int main( int argc, char *argv[] )
{
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB
#ifdef USE_ZBUFFER
| GLUT_DEPTH
#endif
| GLUT_STENCIL);
glutInitWindowPosition( 0, 0 );
glutInitWindowSize(400, 300 );
glutCreateWindow(argv[0]);
glutReshapeFunc(reshape);
glutDisplayFunc(draw_scene);
glutKeyboardFunc(Key);
glutSpecialFunc(SpecialKey);
glutIdleFunc(idle);
init();
glutMainLoop();
return 0;
}