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xenocara/app/xlockmore/modes/glx/moebius.c

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Importing xlockmore 5.22
2006-11-26 04:07:42 -07:00
/* -*- Mode: C; tab-width: 4 -*- */
/* moebius --- Moebius Strip II, an Escher-like GL scene with ants. */
#if !defined( lint ) && !defined( SABER )
static const char sccsid[] = "@(#)moebius.c 5.01 2001/03/01 xlockmore";
#endif
/*-
* 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
* mistakes.
*
* My e-mail address is
* mfvianna@centroin.com.br
*
* Marcelo F. Vianna (Jun-01-1997)
*
* Revision History:
* 05-Apr-2002: Removed all gllist uses (fix some bug with nvidia driver)
* 01-Mar-2001: backported from xscreensaver by lassauge AT users.sourceforge.net
* Feb-2001: Made motion and rotation be smoother Jamie Zawinski
* <jwz@jwz.org>
* 01-Nov-2000: Allocation checks
* 01-Jan-1998: Mode separated from escher and renamed
* 08-Jun-1997: 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-1997: Speed ups in Moebius Strip using GL_CULL_FACE.
* Marcelo F. Vianna.
* 03-Jun-1997: 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).
*/
#ifdef VMS
#include <X11/Intrinsic.h>
#endif
#ifdef STANDALONE
# define MODE_moebius
# define PROGCLASS "Moebius"
# define HACK_INIT init_moebius
# define HACK_DRAW draw_moebius
# define HACK_RESHAPE reshape_moebius
# define moebius_opts xlockmore_opts
# define DEFAULTS "*cycles: 1 \n" \
"*delay: 30000 \n" \
"*showFps: False \n" \
"*wireframe: False \n"
# include "xlockmore.h" /* from the xscreensaver distribution */
#else /* !STANDALONE */
# include "xlock.h" /* from the xlockmore distribution */
# include "visgl.h"
#endif /* !STANDALONE */
#ifdef MODE_moebius
#include <GL/glu.h>
#include "e_textures.h"
#define DEF_SOLIDMOEBIUS "False"
#define DEF_NOANTS "False"
static int solidmoebius;
static int noants;
static XrmOptionDescRec opts[] =
{
{(char *) "-solidmoebius", (char *) ".moebius.solidmoebius", XrmoptionNoArg, (caddr_t) "on"},
{(char *) "+solidmoebius", (char *) ".moebius.solidmoebius", XrmoptionNoArg, (caddr_t) "off"},
{(char *) "-noants", (char *) ".moebius.noants", XrmoptionNoArg, (caddr_t) "on"},
{(char *) "+noants", (char *) ".moebius.noants", XrmoptionNoArg, (caddr_t) "off"}
};
static argtype vars[] =
{
{(void *) & solidmoebius, (char *) "solidmoebius", (char *) "Solidmoebius", (char *) DEF_SOLIDMOEBIUS, t_Bool},
{(void *) & noants, (char *) "noants", (char *) "Noants", (char *) DEF_NOANTS, t_Bool}
};
static OptionStruct desc[] =
{
{(char *) "-/+solidmoebius", (char *) "select between a SOLID or a NET Moebius Strip"},
{(char *) "-/+noants", (char *) "turn on/off walking ants"}
};
ModeSpecOpt moebius_opts =
{sizeof opts / sizeof opts[0], opts, sizeof vars / sizeof vars[0], vars, desc};
#ifdef USE_MODULES
ModStruct moebius_description =
{"moebius", "init_moebius", "draw_moebius", "release_moebius",
"draw_moebius", "change_moebius", (char *) NULL, &moebius_opts,
30000, 1, 1, 1, 4, 1.0, "",
"Shows Moebius Strip II, an Escher-like GL scene with ants", 0, NULL};
#endif
#define Scale4Window 0.3
#define Scale4Iconic 0.4
#define sqr(A) ((A)*(A))
#ifndef Pi
#define Pi M_PI
#endif
#define ObjMoebiusStrip 0
#define ObjAntBody 1
#define MaxObj 2
/*************************************************************************/
typedef struct {
GLint WindH, WindW;
GLfloat step;
GLfloat ant_position;
GLXContext *glx_context;
GLfloat rotx, roty, rotz; /* current object rotation */
GLfloat dx, dy, dz; /* current rotational velocity */
GLfloat ddx, ddy, ddz; /* current rotational acceleration */
GLfloat d_max; /* max velocity */
} moebiusstruct;
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 MaterialRed[] =
{0.7, 0.0, 0.0, 1.0};
static float MaterialGreen[] =
{0.1, 0.5, 0.2, 1.0};
static float MaterialBlue[] =
{0.0, 0.0, 0.7, 1.0};
static float MaterialCyan[] =
{0.2, 0.5, 0.7, 1.0};
static float MaterialYellow[] =
{0.7, 0.7, 0.0, 1.0};
static float MaterialMagenta[] =
{0.6, 0.2, 0.5, 1.0};
static float MaterialWhite[] =
{0.7, 0.7, 0.7, 1.0};
static float MaterialGray[] =
{0.2, 0.2, 0.2, 1.0};
static float MaterialGray5[] =
{0.5, 0.5, 0.5, 1.0};
static float MaterialGray6[] =
{0.6, 0.6, 0.6, 1.0};
static float MaterialGray8[] =
{0.8, 0.8, 0.8, 1.0};
static moebiusstruct *moebius = (moebiusstruct *) NULL;
#define NUM_SCENES 2
static Bool
mySphere(float radius)
{
GLUquadricObj *quadObj;
if ((quadObj = gluNewQuadric()) == 0)
return False;
gluQuadricDrawStyle(quadObj, (GLenum) GLU_FILL);
gluSphere(quadObj, radius, 16, 16);
gluDeleteQuadric(quadObj);
return True;
}
static Bool
myCone(float radius)
{
GLUquadricObj *quadObj;
if ((quadObj = gluNewQuadric()) == 0)
return False;
gluQuadricDrawStyle(quadObj, (GLenum) GLU_FILL);
gluCylinder(quadObj, radius, 0, radius * 3, 8, 1);
gluDeleteQuadric(quadObj);
return True;
}
static Bool
draw_moebius_ant(float *Material, int mono)
{
static float ant_step = 0;
float cos1 = cos(ant_step);
float cos2 = cos(ant_step + 2 * Pi / 3);
float cos3 = cos(ant_step + 4 * Pi / 3);
float sin1 = sin(ant_step);
float sin2 = sin(ant_step + 2 * Pi / 3);
float sin3 = sin(ant_step + 4 * Pi / 3);
if (mono)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray5);
else
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Material);
glEnable(GL_CULL_FACE);
glPushMatrix();
glScalef(1, 1.3, 1);
if (!mySphere(0.18))
return False;
glScalef(1, 1 / 1.3, 1);
glTranslatef(0.00, 0.30, 0.00);
if (!mySphere(0.2))
return False;
glTranslatef(-0.05, 0.17, 0.05);
glRotatef(-90, 1, 0, 0);
glRotatef(-25, 0, 1, 0);
if (!myCone(0.05))
return False;
glTranslatef(0.00, 0.10, 0.00);
if (!myCone(0.05))
return False;
glRotatef(25, 0, 1, 0);
glRotatef(90, 1, 0, 0);
glScalef(1, 1.3, 1);
glTranslatef(0.15, -0.65, 0.05);
if (!mySphere(0.25))
return False;
glScalef(1, 1 / 1.3, 1);
glPopMatrix();
glDisable(GL_CULL_FACE);
glDisable(GL_LIGHTING);
/* ANTENNAS */
glBegin(GL_LINES);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.30, 0.00);
glColor3fv(MaterialGray);
glVertex3f(0.40, 0.70, 0.40);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.30, 0.00);
glColor3fv(MaterialGray);
glVertex3f(0.40, 0.70, -0.40);
glEnd();
glBegin(GL_POINTS);
if (mono)
glColor3fv(MaterialGray6);
else
glColor3fv(MaterialRed);
glVertex3f(0.40, 0.70, 0.40);
glVertex3f(0.40, 0.70, -0.40);
glEnd();
/* LEFT-FRONT ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.05, 0.18);
glVertex3f(0.35 + 0.05 * cos1, 0.15, 0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 + 0.05 * cos1, 0.25 + 0.1 * sin1, 0.45);
glEnd();
/* LEFT-CENTER ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.00, 0.18);
glVertex3f(0.35 + 0.05 * cos2, 0.00, 0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 + 0.05 * cos2, 0.00 + 0.1 * sin2, 0.45);
glEnd();
/* LEFT-BACK ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, -0.05, 0.18);
glVertex3f(0.35 + 0.05 * cos3, -0.15, 0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 + 0.05 * cos3, -0.25 + 0.1 * sin3, 0.45);
glEnd();
/* RIGHT-FRONT ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.05, -0.18);
glVertex3f(0.35 - 0.05 * sin1, 0.15, -0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 - 0.05 * sin1, 0.25 + 0.1 * cos1, -0.45);
glEnd();
/* RIGHT-CENTER ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, 0.00, -0.18);
glVertex3f(0.35 - 0.05 * sin2, 0.00, -0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 - 0.05 * sin2, 0.00 + 0.1 * cos2, -0.45);
glEnd();
/* RIGHT-BACK ARM */
glBegin(GL_LINE_STRIP);
if (mono)
glColor3fv(MaterialGray5);
else
glColor3fv(Material);
glVertex3f(0.00, -0.05, -0.18);
glVertex3f(0.35 - 0.05 * sin3, -0.15, -0.25);
glColor3fv(MaterialGray);
glVertex3f(-0.20 - 0.05 * sin3, -0.25 + 0.1 * cos3, -0.45);
glEnd();
glBegin(GL_POINTS);
if (mono)
glColor3fv(MaterialGray8);
else
glColor3fv(MaterialMagenta);
glVertex3f(-0.20 + 0.05 * cos1, 0.25 + 0.1 * sin1, 0.45);
glVertex3f(-0.20 + 0.05 * cos2, 0.00 + 0.1 * sin2, 0.45);
glVertex3f(-0.20 + 0.05 * cos3, -0.25 + 0.1 * sin3, 0.45);
glVertex3f(-0.20 - 0.05 * sin1, 0.25 + 0.1 * cos1, -0.45);
glVertex3f(-0.20 - 0.05 * sin2, 0.00 + 0.1 * cos2, -0.45);
glVertex3f(-0.20 - 0.05 * sin3, -0.25 + 0.1 * cos3, -0.45);
glEnd();
glEnable(GL_LIGHTING);
ant_step += 0.3;
return True;
}
static void
RotateAaroundU(float Ax, float Ay, float Az,
float Ux, float Uy, float Uz,
float *Cx, float *Cy, float *Cz,
float Theta)
{
float cosO = cos(Theta);
float sinO = sin(Theta);
float one_cosO = 1 - cosO;
float Ux2 = sqr(Ux);
float Uy2 = sqr(Uy);
float Uz2 = sqr(Uz);
float UxUy = Ux * Uy;
float UxUz = Ux * Uz;
float UyUz = Uy * Uz;
*Cx = (Ux2 + cosO * (1 - Ux2)) * Ax + (UxUy * one_cosO - Uz * sinO) * Ay + (UxUz * one_cosO + Uy * sinO) * Az;
*Cy = (UxUy * one_cosO + Uz * sinO) * Ax + (Uy2 + cosO * (1 - Uy2)) * Ay + (UyUz * one_cosO - Ux * sinO) * Az;
*Cz = (UxUz * one_cosO - Uy * sinO) * Ax + (UyUz * one_cosO + Ux * sinO) * Ay + (Uz2 + cosO * (1 - Uz2)) * Az;
}
#define MoebiusDivisions 40
#define MoebiusTransversals 4
static Bool
draw_moebius_strip(ModeInfo * mi)
{
GLfloat Phi, Theta;
GLfloat cPhi, sPhi;
moebiusstruct *mp = &moebius[MI_SCREEN(mi)];
int i, j;
int mono = MI_IS_MONO(mi);
float Cx, Cy, Cz;
if (solidmoebius) {
glBegin(GL_QUAD_STRIP);
Phi = 0;
i = 0;
while (i < (MoebiusDivisions * 2 + 1)) {
Theta = Phi / 2;
cPhi = cos(Phi);
sPhi = sin(Phi);
i++;
if (mono)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
else if (i % 2)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
else
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
RotateAaroundU(cPhi, sPhi, 0, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
glNormal3f(Cx, Cy, Cz);
RotateAaroundU(0, 0, 1, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
glVertex3f(cPhi * 3 + Cx, sPhi * 3 + Cy, +Cz);
glVertex3f(cPhi * 3 - Cx, sPhi * 3 - Cy, -Cz);
Phi += Pi / MoebiusDivisions;
}
glEnd();
} else {
for (j = -MoebiusTransversals; j < MoebiusTransversals; j++) {
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glBegin(GL_QUAD_STRIP);
Phi = 0;
i = 0;
while (i < (MoebiusDivisions * 2 + 1)) {
Theta = Phi / 2;
cPhi = cos(Phi);
sPhi = sin(Phi);
RotateAaroundU(cPhi, sPhi, 0, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
glNormal3f(Cx, Cy, Cz);
RotateAaroundU(0, 0, 1, -sPhi, cPhi, 0, &Cx, &Cy, &Cz, Theta);
j++;
if (j == MoebiusTransversals || mono)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
else if (i % 2)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
else
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
glVertex3f(cPhi * 3 + Cx / MoebiusTransversals * j, sPhi * 3 + Cy / MoebiusTransversals * j, +Cz / MoebiusTransversals * j);
j--;
if (j == -MoebiusTransversals || mono)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialWhite);
else if (i % 2)
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialRed);
else
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, MaterialGray);
glVertex3f(cPhi * 3 + Cx / MoebiusTransversals * j, sPhi * 3 + Cy / MoebiusTransversals * j, +Cz / MoebiusTransversals * j);
Phi += Pi / MoebiusDivisions;
i++;
}
glEnd();
}
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
}
if (!noants) {
/* DRAW BLUE ANT */
glPushMatrix();
glRotatef(mp->ant_position + 180, 0, 0, 1);
glTranslatef(3, 0, 0);
glRotatef(mp->ant_position / 2 + 90, 0, 1, 0);
glTranslatef(0.28, 0, -0.45);
if (!draw_moebius_ant(MaterialYellow, mono))
return False;
glPopMatrix();
/* DRAW YELLOW ANT */
glPushMatrix();
glRotatef(mp->ant_position, 0, 0, 1);
glTranslatef(3, 0, 0);
glRotatef(mp->ant_position / 2, 0, 1, 0);
glTranslatef(0.28, 0, -0.45);
if (!draw_moebius_ant(MaterialBlue, mono))
return False;
glPopMatrix();
/* DRAW GREEN ANT */
glPushMatrix();
glRotatef(-mp->ant_position, 0, 0, 1);
glTranslatef(3, 0, 0);
glRotatef(-mp->ant_position / 2, 0, 1, 0);
glTranslatef(0.28, 0, 0.45);
glRotatef(180, 1, 0, 0);
if (!draw_moebius_ant(MaterialGreen, mono))
return False;
glPopMatrix();
/* DRAW CYAN ANT */
glPushMatrix();
glRotatef(-mp->ant_position + 180, 0, 0, 1);
glTranslatef(3, 0, 0);
glRotatef(-mp->ant_position / 2 + 90, 0, 1, 0);
glTranslatef(0.28, 0, 0.45);
glRotatef(180, 1, 0, 0);
if (!draw_moebius_ant(MaterialCyan, mono))
return False;
glPopMatrix();
}
mp->ant_position += 1;
return True;
}
#undef MoebiusDivisions
#undef MoebiusTransversals
static void
reshape_moebius(ModeInfo * mi, int width, int height)
{
moebiusstruct *mp = &moebius[MI_SCREEN(mi)];
glViewport(0, 0, mp->WindW = (GLint) width, mp->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);
}
}
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);
/* moebius */
glShadeModel(GL_SMOOTH);
glEnable(GL_DEPTH_TEST);
glDisable(GL_TEXTURE_2D);
glDisable(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);
}
/* lifted from lament.c */
#define RANDSIGN() ((LRAND() & 1) ? 1 : -1)
#define FLOATRAND(a) (((double)LRAND() / (double)MAXRAND) * a)
static void
rotate(GLfloat *pos, GLfloat *v, GLfloat *dv, GLfloat max_v, Bool verbose)
{
double ppos = *pos;
/* tick position */
if (ppos < 0)
ppos = -(ppos + *v);
else
ppos += *v;
if (ppos > 1.0)
ppos -= 1.0;
else if (ppos < 0)
ppos += 1.0;
if ((ppos < 0.0) || (ppos > 1.0)) {
if (verbose) {
(void) fprintf(stderr, "Weirdness in rotate()\n");
(void) fprintf(stderr, "ppos = %g\n", ppos);
}
return;
}
*pos = (*pos > 0 ? ppos : -ppos);
/* accelerate */
*v += *dv;
/* clamp velocity */
if (*v > max_v || *v < -max_v)
{
*dv = -*dv;
}
/* If it stops, start it going in the other direction. */
else if (*v < 0)
{
if (random() % 4)
{
*v = 0;
/* keep going in the same direction */
if (random() % 2)
*dv = 0;
else if (*dv < 0)
*dv = -*dv;
}
else
{
/* reverse gears */
*v = -*v;
*dv = -*dv;
*pos = -*pos;
}
}
/* Alter direction of rotational acceleration randomly. */
if (! (random() % 120))
*dv = -*dv;
/* Change acceleration very occasionally. */
if (! (random() % 200))
{
if (*dv == 0)
*dv = 0.00001;
else if (random() & 1)
*dv *= 1.2;
else
*dv *= 0.8;
}
}
void
release_moebius(ModeInfo * mi)
{
if (moebius != NULL) {
free(moebius);
moebius = (moebiusstruct *) NULL;
}
FreeAllGL(mi);
}
void
init_moebius(ModeInfo * mi)
{
moebiusstruct *mp;
if (moebius == NULL) {
if ((moebius = (moebiusstruct *) calloc(MI_NUM_SCREENS(mi),
sizeof (moebiusstruct))) == NULL)
return;
}
mp = &moebius[MI_SCREEN(mi)];
mp->step = NRAND(90);
mp->ant_position = NRAND(90);
mp->rotx = FLOATRAND(1.0) * RANDSIGN();
mp->roty = FLOATRAND(1.0) * RANDSIGN();
mp->rotz = FLOATRAND(1.0) * RANDSIGN();
/* bell curve from 0-1.5 degrees, avg 0.75 */
mp->dx = (FLOATRAND(1) + FLOATRAND(1) + FLOATRAND(1)) / (360*2);
mp->dy = (FLOATRAND(1) + FLOATRAND(1) + FLOATRAND(1)) / (360*2);
mp->dz = (FLOATRAND(1) + FLOATRAND(1) + FLOATRAND(1)) / (360*2);
mp->d_max = mp->dx * 2;
mp->ddx = 0.00006 + FLOATRAND(0.00003);
mp->ddy = 0.00006 + FLOATRAND(0.00003);
mp->ddz = 0.00006 + FLOATRAND(0.00003);
mp->ddx = 0.00001;
mp->ddy = 0.00001;
mp->ddz = 0.00001;
if ((mp->glx_context = init_GL(mi)) != NULL) {
reshape_moebius(mi, MI_WIDTH(mi), MI_HEIGHT(mi));
glDrawBuffer(GL_BACK);
pinit();
} else {
MI_CLEARWINDOW(mi);
}
}
void
draw_moebius(ModeInfo * mi)
{
moebiusstruct *mp;
Display *display = MI_DISPLAY(mi);
Window window = MI_WINDOW(mi);
if (moebius == NULL)
return;
mp = &moebius[MI_SCREEN(mi)];
MI_IS_DRAWN(mi) = True;
if (!mp->glx_context)
return;
glXMakeCurrent(display, window, *(mp->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 * mp->WindH / mp->WindW, Scale4Window, Scale4Window);
} else {
glScalef(Scale4Iconic * mp->WindH / mp->WindW, Scale4Iconic, Scale4Iconic);
}
{
GLfloat x = mp->rotx;
GLfloat y = mp->roty;
GLfloat z = mp->rotz;
if (x < 0) x = 1 - (x + 1);
if (y < 0) y = 1 - (y + 1);
if (z < 0) z = 1 - (z + 1);
glRotatef(x * 360, 1.0, 0.0, 0.0);
glRotatef(y * 360, 0.0, 1.0, 0.0);
glRotatef(z * 360, 0.0, 0.0, 1.0);
}
/* moebius */
if (!draw_moebius_strip(mi)) {
release_moebius(mi);
return;
}
glPopMatrix();
rotate(&mp->rotx, &mp->dx, &mp->ddx, mp->d_max, MI_IS_VERBOSE(mi));
rotate(&mp->roty, &mp->dy, &mp->ddy, mp->d_max, MI_IS_VERBOSE(mi));
rotate(&mp->rotz, &mp->dz, &mp->ddz, mp->d_max, MI_IS_VERBOSE(mi));
if (MI_IS_FPS(mi)) do_fps (mi);
glFlush();
glXSwapBuffers(display, window);
mp->step += 0.025;
}
void
change_moebius(ModeInfo * mi)
{
moebiusstruct *mp = &moebius[MI_SCREEN(mi)];
if (!mp->glx_context)
return;
glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *(mp->glx_context));
pinit();
}
#endif
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