/* -*- Mode: C; tab-width: 4 -*- */
/* cage --- the Impossible Cage, an Escher like scene. */
#if !defined( lint ) && !defined( SABER )
static const char sccsid[] = "@(#)cage.c 4.07 98/01/04 xlockmore";
#endif
#undef DEBUG_LISTS
/*-
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appear in all copies and that
* both that copyright notice and this permission notice appear in
* supporting documentation.
*
* This file is provided AS IS with no warranties of any kind. The author
* shall have no liability with respect to the infringement of copyrights,
* trade secrets or any patents by this file or any part thereof. In no
* event will the author be liable for any lost revenue or profits or
* other special, indirect and consequential damages.
*
* The RotateAroundU() routine was adapted from the book
* "Computer Graphics Principles and Practice
* Foley - vanDam - Feiner - Hughes
* Second Edition" Pag. 227, exercise 5.15.
*
* This mode shows some interesting scenes that are impossible OR very
* wierd to build in the real universe. Much of the scenes are inspirated
* on Mauritz Cornelis Escher's works which derivated the mode's name.
* M.C. Escher (1898-1972) was a dutch artist and many people prefer to
* say he was a mathematician.
*
* Thanks goes to Brian Paul for making it possible and inexpensive to use
* OpenGL at home.
*
* Since I'm not a native English speaker, my apologies for any grammatical
* mistake.
*
* My e-mail address is
* m-vianna@usa.net
*
* Marcelo F. Vianna (Jun-01-1997)
*
* Revision History:
* 01-Jan-98: Mode separated from escher and renamed
* 08-Jun-97: New scene implemented: "Impossible Cage" based in a M.C. Escher's
* painting with the same name (quite similar). The first GL mode
* to use texture mapping.
* The "Impossible Cage" scene doesn't use DEPTH BUFFER, the
* wood planks are drawn consistently using GL_CULL_FACE, and
* the painter's algorithm is used to sort the planks.
* Marcelo F. Vianna.
* 07-Jun-97: Speed ups in Moebius Strip using GL_CULL_FACE.
* Marcelo F. Vianna.
* 03-Jun-97: Initial Release (Only one scene: "Moebius Strip")
* The Moebius Strip scene was inspirated in a M.C. Escher's
* painting named Moebius Strip II in wich ants walk across a
* Moebius Strip path, sometimes meeting each other and sometimes
* being in "opposite faces" (note that the moebius strip has
* only one face and one edge).
* Marcelo F. Vianna.
*
*/
/*-
* Texture mapping is only available on RGBA contexts, Mono and color index
* visuals DO NOT support texture mapping in OpenGL.
*
* BUT Mesa do implements RGBA contexts in pseudo color visuals, so texture
* mapping shuld work on PseudoColor, DirectColor, TrueColor using Mesa. Mono
* is not officially supported for both OpenGL and Mesa, but seems to not crash
* Mesa.
*
* In real OpenGL, PseudoColor DO NOT support texture map (as far as I know).
*/
#include <X11/Intrinsic.h>
#ifdef STANDALONE
#define PROGCLASS "Cage"
#define HACK_INIT init_cage
#define HACK_DRAW draw_cage
#define cage_opts xlockmore_opts
#define DEFAULTS "*delay: 1000 \n" \
"*wireframe: False \n"
#include "xlockmore.h" /* from the xscreensaver distribution */
#else /* !STANDALONE */
#include "xlock.h" /* from the xlockmore distribution */
#include "vis.h"
#endif /* !STANDALONE */
#ifdef MODE_cage
#include <GL/glu.h>
#include "e_textures.h"
ModeSpecOpt cage_opts =
{0, NULL, 0, NULL, NULL};
#ifdef USE_MODULES
ModStruct cage_description =
{"cage", "init_cage", "draw_cage", "release_cage",
"draw_cage", "change_cage", NULL, &cage_opts,
1000, 1, 1, 1, 1.0, 4, "",
"Shows the Impossible Cage, an Escher-like GL scene", 0, NULL};
#endif
#define Scale4Window 0.3
#define Scale4Iconic 0.4
#define sqr(A) ((A)*(A))
#ifndef Pi
#define Pi M_PI
#endif
/*************************************************************************/
typedef struct {
GLint WindH, WindW;
GLfloat step;
int AreObjectsDefined[1];
GLXContext *glx_context;
} cagestruct;
static float front_shininess[] =
{60.0};
static float front_specular[] =
{0.7, 0.7, 0.7, 1.0};
static float ambient[] =
{0.0, 0.0, 0.0, 1.0};
static float diffuse[] =
{1.0, 1.0, 1.0, 1.0};
static float position0[] =
{1.0, 1.0, 1.0, 0.0};
static float position1[] =
{-1.0, -1.0, 1.0, 0.0};
static float lmodel_ambient[] =
{0.5, 0.5, 0.5, 1.0};
static float lmodel_twoside[] =
{GL_TRUE};
static float MaterialWhite[] =
{0.7, 0.7, 0.7, 1.0};
static cagestruct *cage = NULL;
static GLuint objects;
#define ObjWoodPlank 0
#define PlankWidth 3.0
#define PlankHeight 0.35
#define PlankThickness 0.15
static void
draw_woodplank(cagestruct * cp)
{
if (!cp->AreObjectsDefined[ObjWoodPlank]) {
glNewList(objects + ObjWoodPlank, GL_COMPILE_AND_EXECUTE);
glBegin(GL_QUADS);
glNormal3f(0, 0, 1);
glTexCoord2f(0, 0);
glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(PlankWidth, PlankHeight, PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
glNormal3f(0, 0, -1);
glTexCoord2f(0, 0);
glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
glNormal3f(0, 1, 0);
glTexCoord2f(0, 0);
glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(PlankWidth, PlankHeight, PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
glNormal3f(0, -1, 0);
glTexCoord2f(0, 0);
glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
glNormal3f(1, 0, 0);
glTexCoord2f(0, 0);
glVertex3f(PlankWidth, -PlankHeight, PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(PlankWidth, -PlankHeight, -PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(PlankWidth, PlankHeight, -PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(PlankWidth, PlankHeight, PlankThickness);
glNormal3f(-1, 0, 0);
glTexCoord2f(0, 0);
glVertex3f(-PlankWidth, PlankHeight, PlankThickness);
glTexCoord2f(1, 0);
glVertex3f(-PlankWidth, PlankHeight, -PlankThickness);
glTexCoord2f(1, 1);
glVertex3f(-PlankWidth, -PlankHeight, -PlankThickness);
glTexCoord2f(0, 1);
glVertex3f(-PlankWidth, -PlankHeight, PlankThickness);
glEnd();
glEndList();
cp->AreObjectsDefined[ObjWoodPlank] = 1;
#ifdef DEBUG_LISTS
(void) printf("WoodPlank drawn SLOWLY\n");
#endif
} else {
glCallList(objects + ObjWoodPlank);
#ifdef DEBUG_LISTS
(void) printf("WoodPlank drawn quickly\n");
#endif
}
}
static void
draw_impossiblecage(cagestruct * cp)
{
glPushMatrix();
glRotatef(90, 0, 1, 0);
glTranslatef(0.0, PlankHeight - PlankWidth, -PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 0, 1);
glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - PlankThickness);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 1, 0);
glTranslatef(0.0, PlankWidth - PlankHeight, -PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, PlankWidth - PlankHeight, 3 * PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 0, 1);
glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - PlankThickness);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth - 3 * PlankThickness);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, PlankHeight - PlankWidth, 3 * PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 0, 1);
glTranslatef(0.0, PlankHeight - PlankWidth, PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth - 3 * PlankThickness);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 1, 0);
glTranslatef(0.0, PlankHeight - PlankWidth, PlankWidth + PlankThickness);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 0, 1);
glTranslatef(0.0, PlankWidth - PlankHeight, PlankThickness - PlankWidth);
draw_woodplank(cp);
glPopMatrix();
glPushMatrix();
glRotatef(90, 0, 1, 0);
glTranslatef(0.0, PlankWidth - PlankHeight, PlankWidth + PlankThickness);
draw_woodplank(cp);
glPopMatrix();
}
static void
reshape(ModeInfo * mi, int width, int height)
{
cagestruct *cp = &cage[MI_SCREEN(mi)];
glViewport(0, 0, cp->WindW = (GLint) width, cp->WindH = (GLint) height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 15.0);
glMatrixMode(GL_MODELVIEW);
if (width >= 1024) {
glLineWidth(3);
glPointSize(3);
} else if (width >= 512) {
glLineWidth(2);
glPointSize(2);
} else {
glLineWidth(1);
glPointSize(1);
}
cp->AreObjectsDefined[ObjWoodPlank] = 0;
}
static void
pinit(void)
{
glClearDepth(1.0);
glClearColor(0.0, 0.0, 0.0, 1.0);
glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, position0);
glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);
glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);
glLightfv(GL_LIGHT1, GL_POSITION, position1);
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);
glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE, lmodel_twoside);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHT1);
glEnable(GL_NORMALIZE);
glFrontFace(GL_CCW);
glCullFace(GL_BACK);
/* cage */
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
glShadeModel(GL_FLAT);
glDisable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);
glEnable(GL_CULL_FACE);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, WoodTextureWidth, WoodTextureHeight,
GL_RGB, GL_UNSIGNED_BYTE, WoodTextureData);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, front_shininess);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, front_specular);
}
void
init_cage(ModeInfo * mi)
{
int screen = MI_SCREEN(mi);
cagestruct *cp;
if (cage == NULL) {
if ((cage = (cagestruct *) calloc(MI_NUM_SCREENS(mi),
sizeof (cagestruct))) == NULL)
return;
}
cp = &cage[screen];
cp->step = NRAND(90);
if ((cp->glx_context = init_GL(mi)) != NULL) {
reshape(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
glDrawBuffer(GL_BACK);
if (!glIsList(objects))
objects = glGenLists(1);
pinit();
} else {
MI_CLEARWINDOW(mi);
}
}
void
draw_cage(ModeInfo * mi)
{
cagestruct *cp = &cage[MI_SCREEN(mi)];
Display *display = MI_DISPLAY(mi);
Window window = MI_WINDOW(mi);
MI_IS_DRAWN(mi) = True;
if (!cp->glx_context)
return;
glXMakeCurrent(display, window, *(cp->glx_context));
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glTranslatef(0.0, 0.0, -10.0);
if (!MI_IS_ICONIC(mi)) {
glScalef(Scale4Window * cp->WindH / cp->WindW, Scale4Window, Scale4Window);
} else {
glScalef(Scale4Iconic * cp->WindH / cp->WindW, Scale4Iconic, Scale4Iconic);
}
/* cage */
glRotatef(cp->step * 100, 0, 0, 1);
glRotatef(25 + cos(cp->step * 5) * 6, 1, 0, 0);
glRotatef(204.5 - sin(cp->step * 5) * 8, 0, 1, 0);
draw_impossiblecage(cp);
glPopMatrix();
glFlush();
glXSwapBuffers(display, window);
cp->step += 0.025;
}
void
change_cage(ModeInfo * mi)
{
cagestruct *cp = &cage[MI_SCREEN(mi)];
if (!cp->glx_context)
return;
glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(cp->glx_context));
pinit();
}
void
release_cage(ModeInfo * mi)
{
if (cage != NULL) {
(void) free((void *) cage);
cage = NULL;
}
if (glIsList(objects)) {
glDeleteLists(objects, 1);
}
FreeAllGL(mi);
}
#endif
