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Parameters.md

@@ -15,6 +15,115 @@ it may be necessary to modify two constants as follows:
 #define E_SCALE 750.0     /* scaling factor for energy representation */
 ```
 
+### 29 July 21 - Laser in a room of mirrors, with trails and close-up ###
+
+**Program:** Variant of `particle_billiard.c` (to be published later on)
+
+**Initial condition in function `animation()`:** `init_drop_config(x_shooter, y_shooter, 0.0, DPI, configs);`
+
+The effect of showing trails is achieved by switching off double-buffering like this:
+```
+
+```
+int main(int argc, char** argv)
+{
+    glutInit(&argc, argv);
+    if (SHOWTRAILS) glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH);
+    else glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+    glutInitWindowSize(WINWIDTH,WINHEIGHT);
+    glutCreateWindow("Billiard animation");
+       
+    init();
+
+    glutDisplayFunc(display);
+
+    glutMainLoop();
+
+    return 0;
+}
+```
+#define MOVIE 1         /* set to 1 to generate movie */
+
+#define WINWIDTH 	1280  /* window width */
+#define WINHEIGHT 	720   /* window height */
+
+#define XMIN -1.3
+#define XMAX 2.7	/* x interval */
+#define YMIN -1.125
+#define YMAX 1.125	/* y interval for 9/16 aspect ratio */
+
+#define SCALING_FACTOR 1.0       /* scaling factor of drawing, needed for flower billiards, otherwise set to 1.0 */
+
+/* Choice of the billiard table, see global_particles.c */
+
+#define B_DOMAIN 21      /* choice of domain shape */
+
+#define CIRCLE_PATTERN 3    /* pattern of circles */
+
+#define ABSORBING_CIRCLES 1 /* set to 1 for circular scatterers to be absorbing */
+
+#define NMAXCIRCLES 1000        /* total number of circles (must be at least NCX*NCY for square grid) */
+#define NCX 15            /* number of circles in x direction */
+#define NCY 20            /* number of circles in y direction */
+
+#define LAMBDA 1.0	/* parameter controlling shape of billiard */
+#define MU 0.015          /* second parameter controlling shape of billiard */
+#define FOCI 1          /* set to 1 to draw focal points of ellipse */
+#define NPOLY 8             /* number of sides of polygon */
+#define APOLY 0.25           /* angle by which to turn polygon, in units of Pi/2 */ 
+#define DRAW_BILLIARD 1     /* set to 1 to draw billiard */
+#define DRAW_CONSTRUCTION_LINES 1   /* set to 1 to draw additional construction lines for billiard */
+#define PERIODIC_BC 0       /* set to 1 to enforce periodic boundary conditions when drawing particles */
+
+#define RESAMPLE 0      /* set to 1 if particles should be added when dispersion too large */
+#define DEBUG 0         /* draw trajectories, for debugging purposes */
+
+/* Simulation parameters */
+
+#define NPART 5000       /* number of particles */
+#define NPARTMAX 100000	/* maximal number of particles after resampling */
+#define LMAX 0.01       /* minimal segment length triggering resampling */ 
+#define DMIN 0.02       /* minimal distance to boundary for triggering resampling */ 
+#define CYCLE 1         /* set to 1 for closed curve (start in all directions) */
+#define SHOWTRAILS 1    /* set to 1 to keep trails of the particles */
+#define SHOWZOOM 1      /* set to 1 to show a zoom (for laser in room of mirrors) */
+
+#define NSTEPS 2000     /* number of frames of movie */
+#define TIME 1500       /* time between movie frames, for fluidity of real-time simulation */ 
+#define DPHI 0.000005    /* integration step */
+#define NVID 150         /* number of iterations between images displayed on screen */
+
+/* Decreasing TIME accelerates the animation and the movie                               */
+/* For constant speed of movie, TIME*DPHI should be kept constant                        */
+/* However, increasing DPHI too much deterioriates quality of simulation                 */
+/* NVID tells how often a picture is drawn in the animation, increase it for faster anim */
+/* For a good quality movie, take for instance TIME = 400, DPHI = 0.00005, NVID = 100    */
+
+/* Colors and other graphical parameters */
+
+#define NCOLORS 32      /* number of colors */
+#define COLORSHIFT 0     /* hue of initial color */ 
+#define RAINBOW_COLOR 1  /* set to 1 to use different colors for all particles */
+#define FLOWER_COLOR 0   /* set to 1 to adapt initial colors to flower billiard (tracks vs core) */
+#define NSEG 100         /* number of segments of boundary */
+#define LENGTH 0.007      /* length of velocity vectors */
+#define BILLIARD_WIDTH 6    /* width of billiard */
+#define PARTICLE_WIDTH 2    /* width of particles */
+#define FRONT_WIDTH 3       /* width of wave front */
+
+#define BLACK 1             /* set to 1 for black background */
+#define COLOR_OUTSIDE 0     /* set to 1 for colored outside */ 
+#define OUTER_COLOR 270.0   /* color outside billiard */
+#define PAINT_INT 0         /* set to 1 to paint interior in other color (for polygon/Reuleaux) */
+
+
+#define PAUSE 1000       /* number of frames after which to pause */
+#define PSLEEP 1         /* sleep time during pause */
+#define SLEEP1  1        /* initial sleeping time */
+#define SLEEP2  1000      /* final sleeping time */
+
+```
+
 
 ### 28 July 21 - An invisibility cloak (first optimized version) ###
 
@@ -339,7 +448,7 @@ it may be necessary to modify two constants as follows:
 
 ### 25 July 21 - How to avoid being hit by a laser in a room of mirrors ###
 
-**Program:** Variant of `particle_laser.c`
+**Program:** Variant of `particle_billiard.c` (to be published later on)
 
 **Initial condition in function `animation()`:** `init_drop_config(x_shooter, y_shooter, 0.0, DPI, configs);`