Home » Archimedes archive » Acorn User » AU 1997-05 B.adf » Features » 3D/Files/!AUA_ray/source/c/engine
3D/Files/!AUA_ray/source/c/engine
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Archimedes archive » Acorn User » AU 1997-05 B.adf » Features |
| Filename: | 3D/Files/!AUA_ray/source/c/engine |
| Read OK: | ✔ |
| File size: | 5E2B bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
/*
engine.c : Written by Greg Scott 1997
for Acorn User, as part of the "Virtual
Worlds" series.
Usage of the source code is done at the
owners risk, and Acorn User or the auth
or hold no responsibility for damages.
*/
/* AUTHORS NOTE: A lot of the code in here is very complex, and can never be adequately explained. PLEASE PLEASE contact me for more assistance, it is much easier to address personal problems with the ideas than in general.
AUThreeD@aol.com
or contact the Acorn User offices and they will pass it on. Thank you. */
/* ANSI C includes */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
/* OTHER includes */
#include "our_lib.h"
/* DEFINES */
#define WORLD_WIDTH 64 /* This is the number of walls across in our world */
#define WORLD_HEIGHT 64 /* This is the number of walls down in our world */
#define WALL_WIDTH 64 /* This is the width of each wall in pixels */
#define WALL_HEIGHT 64 /* This is the height of each wall in pixels */
#define WALL_NUMBER 20 /* This defines the number of walls allowed */
#define SCREEN_WIDTH 320 /* This is the width of the mode 13 screen */
#define SCREEN_HEIGHT 256 /* This is the height of the mode 13 screen */
#define CELL_X_SIZE 64 /* this is the size in units of each cell */
#define CELL_Y_SIZE 64 /* this is the size in units of each cell */
#define CELL_X_SIZE_FP 6 /* this is used in binary shifting */
#define CELL_Y_SIZE_FP 6 /* this is used in binary shifting */
#define FOUND_WALL 1 /* this flag is used to indicate when an intersection has be found */
/* these defines represent a new fixed point form of angle-counting. Basically this system is used to avoid using floating point radian angles, which (especially on an Acorn) take a long time. It also makes look-up table referencing a lot easier, as the index has to be an integer anyway! */
#define ANGLE_0 0
#define ANGLE_6 30
#define ANGLE_30 160
#define ANGLE_45 240
#define ANGLE_60 320
#define ANGLE_90 480
#define ANGLE_180 960
#define ANGLE_225 1200
#define ANGLE_270 1440
#define ANGLE_360 1920
/* GLOBAL variables */
char world[WORLD_HEIGHT+1][WORLD_WIDTH+1];/* This holds our text data file */
char walls[WALL_NUMBER+1][(WALL_WIDTH*WALL_HEIGHT)+1];
/* This holds the wall graphics in a two dimensional array */
/* Note the usage of char and not "int" in both cases. This is because a char is 8 bytes, which gives 256 colours (used in our Mode 13 screen) and also an integer up to 256, when our text file doesn't go over 9 in number! Hence there is no need for an int array in either case. */
char *screen_address; /* this will hold the base of the screen memory which we will manipulate. By altering values in the screen memory, we alter what appears on the screen. Note that this is of type "char *" because it holds the memory address of a byte array - the 256 colour mode 13 screen (well it will do!) */
/* these FLOATING point (urgh!) pointers point to look-up tables used in the ray casting engine. These are explained of in the engine, but the look-ups are generated in aua_tables() */
float *tan_table,*inv_tan_table; /* pointers to tangent look_ups */
float *y_step,*x_step; /* pointers to more complex look_ups */
float *inv_cos_table, /* sin/cos tables (look_ups) */
*inv_sin_table;
float *cos_table; /* cosinal look_up table */
/* FUNCTION definitions */
/* this function generates LOOK UP tables - arrays holding pre-calculated trigonometric variables used in the ray casting process */
void aua_tables(void)
{
int ang, /* this is used to hold values while making look-ups */
angt; /* same */
float rad_angle; /* this holds the radians equivalent of the fixed point angle system (0-1920 = 0-360 degrees = 0-6.whatever radians */
/* dynamically allocated adequate memory for the look-ups */
tan_table = (float *)malloc(sizeof(float) * (ANGLE_360+1));
inv_tan_table = (float *)malloc(sizeof(float) * (ANGLE_360+1));
y_step = (float *)malloc(sizeof(float) * (ANGLE_360+1));
x_step = (float *)malloc(sizeof(float) * (ANGLE_360+1));
cos_table = (float *)malloc(sizeof(long) * (ANGLE_360+1));
inv_cos_table = (float *)malloc(sizeof(float) * (ANGLE_360+1));
inv_sin_table = (float *)malloc(sizeof(float) * (ANGLE_360+1));
/* generate them, their use is explained in the ray casting engine */
for(angt=ANGLE_0;angt<=ANGLE_360;angt++)
{
ang=angt;
rad_angle=(float)((3.272e-4) + ang * 2*3.141592654/ANGLE_360);
tan_table[ang]=(float)tan(rad_angle);
inv_tan_table[ang]=(float)(1/tan(rad_angle));
if(ang>=ANGLE_0 && ang<ANGLE_180)
{
y_step[ang]=(float)(fabs(tan(rad_angle) * CELL_Y_SIZE));
}
else
y_step[ang]=(float)(-fabs(tan(rad_angle) * CELL_Y_SIZE));
if(ang>=ANGLE_90 && ang<ANGLE_270)
{
x_step[ang]=(float)(-fabs((1/tan(rad_angle)) * CELL_X_SIZE));
}
else
{
x_step[ang]=(float)(fabs((1/tan(rad_angle)) * CELL_X_SIZE));
}
inv_cos_table[ang]=(float)(1/cos(rad_angle));
inv_sin_table[ang]=(float)(1/sin(rad_angle));
}
/* the cosine table is used to get rid of the "fish bowl effect", explained in the ray caster */
for(ang=-ANGLE_30;ang<=ANGLE_30;ang++)
{
rad_angle=(float)((3.272e-4)+ ang * 2*3.141592654/ANGLE_360);
cos_table[ang+ANGLE_30]=(float)(13312/cos(rad_angle));
}
}
/* this function is the heart of the program, the engine, to generate the first person view */
void aua_raycaster(int view_x,int view_y,int view_angle)
{
/* remember that we are thinking in 2-D, not in 3D when we discuss ideas. Below does not mean "a floor below", it really means "behind", but we say below because we are imagining looking down on the view point to form a 2-D plan */
/* this function, for each column of the 320 pixel width Mode 13 screen, casts out two rays. One ray looks for X, horizontal intersections with walls, and the other tracks intersections with Y, vertical wall boundaries. After all, the only time a collision could occur is on a boundary of a cell, as the wall fills up the entire cell. Expect to see lots of 64's, though remember that this ray caster is very routine, and has not at all been put through my "box of magic". The engine will become much more personalised very soon! */
int cell_x, /* used to store which cell of the walls data the ray is in */
cell_y, /* " */
casting=2, /* used to store if ray casting has finished */
x_hit_type, /* this stores the wall type hit by the x casting ray */
y_hit_type, /* this sotres the wall type (number) hit by the y ray */
x_bound, /* this holds the next x boundary for a possible intersection */
y_bound, /* this holds the next y boundary for a possible intersection */
next_y_cell, /* this is used to figure out the quadrant of the ray (+/-)*/
next_x_cell, /* " */
x_delta, /* this is +'d to the x_bound var. to move to the next boundary */
y_delta, /* this is +'d to the y_bound var. to move to the next boundary */
xi_save, /* this stores where the x casting ray made its intersection */
yi_save, /* this stores where the y casting ray made its intersection */
scale, /* this stores the scale of the sliver to be drawn in each column */
ray, /* this stores the ray number being cast out (0-320)*/
xray, /* this flag is used to show if casting is over */
yray, /* " */
dist_x, /* this holds the distance to the x intersection */
dist_y; /* this holds the distance to the y intersection */
float xi,
yi,
xadd,
yadd; /* these are used to accurately trace and move each ray */
long variables[8]; /* this is used to pass variables to a super fast sliver render */
/* firstly, we set up the variables[] we already know, such as screen_address, walls and the screen height we are using. These are all things which our sliver renderer needs to know to plot its column */
variables[0]=(char *)screen_address;
variables[1]=(char *)walls;
variables[5]=SCREEN_HEIGHT;
/* now we get down to the nitty gritty. Here we subtract 30 degrees from the viewing angle remember that our FOV is 60 degrees which means that we cast from -30 to +30 */
if ( (view_angle-=ANGLE_30) < 0)
{
/* this ensures that we don't go over or under 0/360 degrees! */
view_angle=ANGLE_360 + view_angle;
}
/* now we start the main loop, start at the right of the screen (319), and cast each column one by one to the left */
for (ray=319; ray>=0; ray--)
{
/* for each ray to be cast we actually cast out two rays : one to check for vertical boundary collisions and the other to check for horizontal boundary collisions. Considering that walls fill up each cell, we need only look for intersections on the boundaries. We have to perform seperate cast because just casting one ray complicates the matter and it doesn't give much speed increase, if any. */
/* SECTION 1 : CALCULATING THE FIRST X and Y INTERSECTIONS*/
/* Once we have done this the following intersections are easy*/
/* The X CASTING RAY : here we test to see if the angle of the ray is facing upwards. We need to know which halfplane we're casting from relative to the y-axis. */
if (view_angle >= ANGLE_0 && view_angle < ANGLE_180)
{
/* if so then we assign variables to that effect. We must compute the first horizontal line that could be intersected with the ray. Note : it will be above the viewer.*/
y_bound = (CELL_Y_SIZE + (view_y & 0xffc0)); /* this line is merely an optimized version of CELL_Y_SIZE + (view_y % 64). I use it many times in this engine. */
y_delta = CELL_Y_SIZE; /* this means that for every movement of the ray, the y boundary moves up one cell, which it would. It is the delta to get to the next horizontal line */
/* next we use the inverse tan function to calculate the initial position of the x boundary searching ray on its first intersection. We have to use tan because it is related to slopes */
xi = (float)(inv_tan_table[view_angle] * (y_bound - view_y)) +view_x;
/* this means that the quadrant of the ray is not negative, that is the next y boundary will appear above the view point and not below (in terms of looking down on the viewer). This is the cell delta */
next_y_cell = 0;
}
/* if the viewing angle is greater than 180 degrees and less than 270 degrees then we have to do other calculations (lower half plane) */
else
{
/* we know that because the viewing angle is downwards, so then the horizontal intersection has to be BELOW the viewer */
y_bound = (int)(view_y & 0xffc0);
/* because of this we also know that the next Y intersections will be a cell below each other. So the delta for each horizontal intersection will be a cell below the last */
y_delta = -CELL_Y_SIZE;
/* we again use the tangent function, just as before, to calculate the first x intersection with a boundary. */
xi = (float)(inv_tan_table[view_angle] * (y_bound - view_y)) +view_x;
/* and we know also that the quadrant is below the player, so the cell y delta will be negative */
next_y_cell = -1;
}
/* Y RAY : we do similar calculations but this time to calculate the first y intersections */
/* we test to see if the view angle is within the vertical asymptotes of 360 degrees. We need to know which halfplane we're casting from relative to the x-axis. */
if (view_angle < ANGLE_90 || view_angle >= ANGLE_270)
{
/* we can deduce certain things, just as with the x ray. We know that because the view angle is to the right, the next X boundary (which is constant) will be to the RIGHT of the viewer. */
x_bound = (int)(CELL_X_SIZE + (view_x & 0xffc0));
/* notice this recurring optimization of view_x % 64 */
/* and we also know that each vertical cell boundary after the first will be a cell's width away */
x_delta = CELL_X_SIZE;
/* this time we use the tangent function (not the inverse tan) to calculate where the first y boundary intersection will occur). */
yi = (float)(tan_table[view_angle] * (x_bound - view_x)) +view_y;
/* and we know also that because the view is positive, the next_x_cell delta does not need to be negative */
next_x_cell = 0;
}
/* otherwise, if the viewing angle is towards the other direction...*/
else
{
/* we know that the first x boundary can occur only to the left of the viewer because the ray angle is facing left. So we can do view_x % 64 to calculate the first vertical boundary, this should be becoming obvious */
x_bound = (int)(view_x & 0xffc0);
/* we also know that the delta for the cell will be to the left, each time the ray moves to the next boundary the next vertical intersection will be a cell to the left than the last. */
x_delta = -CELL_X_SIZE;
/* we use the tangental function again to calculate the position on the horizontal intersections */
yi =(float)(tan_table[view_angle] * (x_bound - view_x)) +view_y;
/* and we also know that the x cell value will be minus, because as the ray moves to another cell, because the ray is going left, the value must be minus. */
next_x_cell = -1;
}
/* Now we have performed the slightly tricky task of the first intersections, we can move on to calculating the next ones. This is more simple, as we know that the intersections can only occur at cell boundaries.*/
/* SECTION 2 : Testing for further intersections */
/* these flags store if casting of both rays is complete */
xray=yray=0;
/* X Ray is first */
/* because we are testing for each next intersection, we can figure out more easily the following intersections. */
/* this is a look up table holding the next y intercepts, based on the tangental function and the size of cells. Basically we add this to the ray each time we move it a bit more, searching for a wall at a cell boundary */
yadd=y_step[view_angle];
/* start casting the x ray */
while(!xray)
{
/* compute current cell position of the ray to inspect*/
cell_x = ( (x_bound+next_x_cell) >> CELL_X_SIZE_FP);
cell_y = (int)yi>>CELL_X_SIZE_FP;
/* both of the above examples use binary shifting to achieve a divide by 64. Cell_y computation uses identical techniques to those covered in the magazine. Cell_x is calculated by using the x_bound and next_x_cell values calculated beforehand. */
if(cell_x<0)cell_x=0;if(cell_x>63)cell_x=63;
if(cell_y<0)cell_y=0;if(cell_y>63)cell_y=63;
/* these simple lines ensure that the ray doesn't go out of the world, though they aren't really needed. */
/* we look up in the world file to see if there is a wall at the intersection of our ray */
if ((x_hit_type =world[cell_y][cell_x])!=0)
{
/* if so we calculate the distance to it using the old O-Level technique of using sine and cosine instead of doing the standard PYTHAGORAS technique.*/
dist_x = ( (yi - view_y) * inv_sin_table[view_angle]);
/* we also save the exact position of the intersection because we will need it later to add texture mapping. */
yi_save = (int)yi;
/* because the x ray has found a wall, we can stop casting */
xray=FOUND_WALL;
}
else
{
/* if not, we compute the next possible intersection */
yi +=yadd;
x_bound += x_delta; /* and we also calculate the next horizontal boundary, which we know will be x_delta away, no need for complex workings. */
}
}
/* SECTION 3 */
/* WE NOW do exactly the same but for the yray, we cast it out, check for a wall, if there is one we take the distance to it etc, if not, we move the ray until a wall it found. */
/* look up the value to add to the ray each time we move it */
xadd=x_step[view_angle];
/* start casting the ray */
while(!yray)
{
/* compute current cell to inspect */
cell_x = (int)xi>>CELL_Y_SIZE_FP;
cell_y = ( (y_bound + next_y_cell) >> CELL_Y_SIZE_FP);
/* these calculations work out which cells the ray is in, ready to check for walls in the world[][] array. They both use binary shifting to perform divide by 64's. */
/* check that the ray has not gone out of the world, though this isn't really necessary */
if(cell_x<0)cell_x=0;if(cell_x>63)cell_x=63;
if(cell_y<0)cell_y=0;if(cell_y>63)cell_y=63;
/* look and see if there is a wall at the current point of intersection */
if ((y_hit_type = world[cell_y][cell_x])!=0)
{
/* Use the old O-Level triangle method of calulating distance using cos, rather than using PYTHAGORAS, which is slower because it uses a square root! */
dist_y = ( (xi - view_x) * inv_cos_table[view_angle] );
/* save the exact intersection point, we will need it later */
xi_save = (int)xi;
/* STOP y casting in that case, a wall has been found. */
yray=FOUND_WALL;
}
else
{
/* if not, move the ray on */
xi+=xadd;
y_bound += y_delta; /* and move to the next vertical boundary position */
}
}
/* SECTION 4*/
/* Both rays have been cast, both rays have met a wall, we now need to see which is closer, and then plot it correctly. */
/* find out which wall (x or y) is nearer the viewer. */
if (dist_x < dist_y)
{
/* make sure that no divide by zeros occur */
if(dist_x<1)dist_x=1;
/* we need to take into account here, when computing the scale of the vertical strip (sliver) to be drawn, a phenemenon (of sorts) known as the "fish bowl effect". This is caused by mizing of cartesian and polar coordinates. To get rid of it we use the cosine function. I have combined other multiplies of a vertical scaling factor with the cosine transformation to save time. All we eventually be explained. You could replace the line with scale=13312/dist_x++ and see what weird results you get! */
scale = cos_table[ray]/dist_x++;
/* assign the variables we need to the variables to be passed to the ASM sliver renderer (super fast!) */
variables[2]=(yi_save & 0x003f); /* this works out the column of the wall to be plotted (0-64), by calculating where abouts in the cell the intersection was, covered in the article. Note the optimization of yi_save % 64 */
variables[3]=scale-1; /*stores the scale of the strip (height of it)*/
variables[4]=ray; /* we use ray as the x position to plot to (0-319)*/
variables[6]=x_hit_type; /* finally we store the wall number to plot */
/* and we call the assembler function (explained at a later date)*/
ourlib_sliver(&variables[0]);
}
/* else the dist_y was nearer, everything from above applies */
else
{
/* avoid divide by zero */
if(dist_y<1)dist_y=1;
/* avoid fish bowl effect, see above */
scale = (int)cos_table[ray]/dist_y++;
/* set up variables for our sliver engine, see above */
variables[2]=(xi_save & 0x003f); /*notice that we use xi instead of yi_save*/
variables[3]=scale-1;
variables[4]=ray;
variables[6]=y_hit_type;
/* call our sliver engine */
ourlib_sliver(&variables[0]);
}
/* this ray has been finished. Increase the angle of the next ray and start again! */
if (++view_angle>=ANGLE_360)
{
/* this ensures that the ray angle doesn't go over 360 degrees! */
view_angle=0;
}
/* ray loop */
}
/* end ray caster engine */
}
/* this function grabs all the different walls from a single file */
void aua_graphics(void)
{
int x, /* this is used to store the x coordinate of a point on the screen */
y, /* this is used to store the y coordinate of a point on the screen */
wall_number; /* this will be used to index the walls[x][] char array */
/* first of all we get the graphics file <AUARay$Dir>.graphics onto the screen */
system("*ScreenLoad <AUARay$Dir>.graphics");
/* next we start grabbing each tile, 64 x 64 pixels, into the walls[][] array */
/* we use this large for loop at the ourlib_bitmap_grab function to invidually grab each tile into its own walls[x][] array slot, note that we CAN'T HAVE WALL 0 as this represents a gap in the world! */
for(wall_number=1,y=0;y<SCREEN_HEIGHT;y+=WALL_HEIGHT)for(x=0;x<SCREEN_WIDTH;x+=WALL_WIDTH,wall_number++)
{
/* this calls the function ourlib_bitmap_grab (I said it would be handy!) which grabs the area of screen memory marked by the first four parameters, stores it in the byte array pointer in parameter five, reading it all from the screen pointed to by screen_address */
ourlib_bitmap_grab(x,y,x+WALL_WIDTH-1,y+WALL_HEIGHT-1,&walls[wall_number][0],screen_address);
/* this makes sure we don't go over our number of walls limit */
if(wall_number>=WALL_NUMBER)break;
}
}
/* this function loads in the data from our world text file and stores it in the world[][] array */
void aua_world(void)
{
FILE *world_file; /* we need a file pointer as we will be loading in text */
int row, /* this will be used to index the world[][] array */
column; /* this will be used to index the world[][] array */
char ch; /* this is used to store each number as it is loaded in */
/* open the world file, if it is not there then exit the program */
if(!(world_file=fopen("<AUARay$Dir>.world","r")))exit(1);
/* this program loads in the data from the world file, row by row, column by column using the getc() ANSI function */
for(row=0;row<WORLD_HEIGHT;row++)
{
for(column=0;column<WORLD_WIDTH;column++)
{
while((ch=getc(world_file))==10){} /* this filters out any mess, though not often used! */
if(ch==' ')ch=0; /*this ensures the correct value is stored, if there is a gap in the file, this means a space in the world, a zero */
else ch=ch-'0';
world[(WORLD_HEIGHT-1)-row][column]=ch; /* this finally stores the value in the correct position */
/*printf("%d",ch); uncomment this line to see the world data loaded in */
}
/*printf("\n"); uncomment this line to see the world data loaded in */
}
/* when all is done, close the file */
fclose(world_file);
}
/* MAIN function */
void main(void)
{
int view_x, /* this holds the viewing x coordinate */
view_y, /* this holds the viewing y coordinate */
view_angle; /* this holds the viewing angle in fixed units 0-1920 */
int key_press; /* this is used to confirm input of values */
/* first, we need the user to input values for view_x,view_y and view_angle*/
printf("********** RAY CASTING DEMONSTRATION ***********\nPLEASE enter values for VIEWING X (200-3800 rcmd.), VIEWING Y (200-3800) and VIEWING_ANGLE (0-1920, where 1920=360 degrees etc...).\n\nThe program will take a screenshot of the rendered view, and store it inside the !AUARay application directory.\n\nThis early version is quite unstable, and is purely designed to give an example of how ray casting can be applied to C source code. Staying within the recommended coordinates is a wise move, and pay special attention to keeping the view point OUT of walls!\nIf you are using the program with the world file supplied, try 400,400,100\n************************************************\n");
scanf("%d %d %d",&view_x,&view_y,&view_angle);
/* confirm this is ok */
printf("You entered %d %d and %d Press 0 to quit and re-enter or any other number to continue...\n",view_x,view_y,view_angle);
scanf("%d",&key_press);
/* if q is pressed then exit, else continue */
if(!key_press)exit(1);
/* now we call aua_world to load in the text world file which defines our walls type and layout */
printf("loading in text file <AUARay$Dir>.world\n");
aua_world();
/* check to see if the viewer is inside a game cell WALL, which would be bad news! */
if(world[view_y>>6][view_x>>6])
{
printf("Bad coordinates given, viewer is IN a WALL!, exiting\n");
exit(1);
}
/* now we call aua_tables to generate some look-up tables for the engine to use, look-ups are explained up at the top of the file next to the global variables */
printf("calling aua_tables() this could take a long time on some machines\n");
aua_tables();
/* all is done in terms of input for now. We need to switch to Mode 13 */
printf("Switching to Mode 13\n");
/* call ourlib_changemode to switch to mode 13 */
ourlib_changemode(13);
/* call ourlib_findscreen to get the screen base address of mode 13, without the correct address we can't draw anything and the computer could crash */
screen_address=(char *)ourlib_findscreen();
/* now we need to *screenload our graphics file, and grab each individual wall graphic one by one, the function aua_graphics does this */
aua_graphics();
/* NOW we can go to mode 13 again and call the ray caster function */
ourlib_changemode(13);
aua_raycaster(view_x,view_y,view_angle);
/* take a screenshot, using *screen save, and save it inside the directory */
system("*ScreenSave <AUARay$Dir>.scrshot");
}
00000000 2f 2a 0a 20 20 20 65 6e 67 69 6e 65 2e 63 20 3a |/*. engine.c :|
00000010 20 57 72 69 74 74 65 6e 20 62 79 20 47 72 65 67 | Written by Greg|
00000020 20 53 63 6f 74 74 20 20 20 31 39 39 37 0a 20 20 | Scott 1997. |
00000030 20 66 6f 72 20 41 63 6f 72 6e 20 55 73 65 72 2c | for Acorn User,|
00000040 20 61 73 20 70 61 72 74 20 6f 66 20 74 68 65 20 | as part of the |
00000050 22 56 69 72 74 75 61 6c 0a 20 20 20 57 6f 72 6c |"Virtual. Worl|
00000060 64 73 22 20 73 65 72 69 65 73 2e 0a 0a 20 20 20 |ds" series... |
00000070 55 73 61 67 65 20 6f 66 20 74 68 65 20 73 6f 75 |Usage of the sou|
00000080 72 63 65 20 63 6f 64 65 20 69 73 20 64 6f 6e 65 |rce code is done|
00000090 20 61 74 20 74 68 65 0a 20 20 20 6f 77 6e 65 72 | at the. owner|
000000a0 73 20 72 69 73 6b 2c 20 61 6e 64 20 41 63 6f 72 |s risk, and Acor|
000000b0 6e 20 55 73 65 72 20 6f 72 20 74 68 65 20 61 75 |n User or the au|
000000c0 74 68 0a 20 20 20 6f 72 20 68 6f 6c 64 20 6e 6f |th. or hold no|
000000d0 20 72 65 73 70 6f 6e 73 69 62 69 6c 69 74 79 20 | responsibility |
000000e0 66 6f 72 20 64 61 6d 61 67 65 73 2e 0a 2a 2f 0a |for damages..*/.|
000000f0 0a 2f 2a 20 41 55 54 48 4f 52 53 20 4e 4f 54 45 |./* AUTHORS NOTE|
00000100 3a 20 41 20 6c 6f 74 20 6f 66 20 74 68 65 20 63 |: A lot of the c|
00000110 6f 64 65 20 69 6e 20 68 65 72 65 20 69 73 20 76 |ode in here is v|
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000054c0 2a 2a 2a 2a 2a 2a 20 52 41 59 20 43 41 53 54 49 |****** RAY CASTI|
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000054f0 45 41 53 45 20 65 6e 74 65 72 20 76 61 6c 75 65 |EASE enter value|
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00005dd0 20 73 61 76 65 2c 20 61 6e 64 20 73 61 76 65 20 | save, and save |
00005de0 69 74 20 69 6e 73 69 64 65 20 74 68 65 20 64 69 |it inside the di|
00005df0 72 65 63 74 6f 72 79 20 2a 2f 0a 0a 73 79 73 74 |rectory */..syst|
00005e00 65 6d 28 22 2a 53 63 72 65 65 6e 53 61 76 65 20 |em("*ScreenSave |
00005e10 3c 41 55 41 52 61 79 24 44 69 72 3e 2e 73 63 72 |<AUARay$Dir>.scr|
00005e20 73 68 6f 74 22 29 3b 0a 7d 0a 0a |shot");.}..|
00005e2b 
.