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+/* $Id: reflect.c,v 1.1 1999/08/19 00:55:40 jtg 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 1.1 1999/08/19 00:55:40 jtg
+ * Initial revision
+ *
+ * Revision 3.4 1999/03/28 18:22:05 brianp
+ * minor clean-up
+ *
+ * Revision 3.3 1998/11/22 02:54:29 brianp
+ * only draw one stack for gluCylinders
+ *
+ * Revision 3.2 1998/11/19 02:53:48 brianp
+ * changed texture image and background color
+ *
+ * Revision 3.1 1998/11/05 04:34:04 brianp
+ * moved image files to ../images/ directory
+ *
+ * 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 "../images/tile.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, 1 );
+ 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, 1 );
+ 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, 0.9, 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 )
+{
+ (void) eyex;
+ (void) eyey;
+ (void) 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 )
+{
+ (void) x;
+ (void) y;
+ if (key==27)
+ exit(0);
+}
+
+
+static void SpecialKey( int key, int x, int y )
+{
+ (void) x;
+ (void) 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;
+}
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