redis_study/src/lolwut6.c
2020-09-05 12:01:22 +08:00

202 lines
7.9 KiB
C

/*
* Copyright (c) 2019, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ----------------------------------------------------------------------------
*
* This file implements the LOLWUT command. The command should do something
* fun and interesting, and should be replaced by a new implementation at
* each new version of Redis.
*
* Thanks to Michele Hiki Falcone for the original image that ispired
* the image, part of his game, Plaguemon.
*
* Thanks to the Shhh computer art collective for the help in tuning the
* output to have a better artistic effect.
*/
#include "server.h"
#include "lolwut.h"
/* Render the canvas using the four gray levels of the standard color
* terminal: they match very well to the grayscale display of the gameboy. */
static sds renderCanvas(lwCanvas *canvas) {
sds text = sdsempty();
for (int y = 0; y < canvas->height; y++) {
for (int x = 0; x < canvas->width; x++) {
int color = lwGetPixel(canvas,x,y);
char *ce; /* Color escape sequence. */
/* Note that we set both the foreground and background color.
* This way we are able to get a more consistent result among
* different terminals implementations. */
switch(color) {
case 0: ce = "0;30;40m"; break; /* Black */
case 1: ce = "0;90;100m"; break; /* Gray 1 */
case 2: ce = "0;37;47m"; break; /* Gray 2 */
case 3: ce = "0;97;107m"; break; /* White */
default: ce = "0;30;40m"; break; /* Just for safety. */
}
text = sdscatprintf(text,"\033[%s \033[0m",ce);
}
if (y != canvas->height-1) text = sdscatlen(text,"\n",1);
}
return text;
}
/* Draw a skyscraper on the canvas, according to the parameters in the
* 'skyscraper' structure. Window colors are random and are always one
* of the two grays. */
struct skyscraper {
int xoff; /* X offset. */
int width; /* Pixels width. */
int height; /* Pixels height. */
int windows; /* Draw windows if true. */
int color; /* Color of the skyscraper. */
};
void generateSkyscraper(lwCanvas *canvas, struct skyscraper *si) {
int starty = canvas->height-1;
int endy = starty - si->height + 1;
for (int y = starty; y >= endy; y--) {
for (int x = si->xoff; x < si->xoff+si->width; x++) {
/* The roof is four pixels less wide. */
if (y == endy && (x <= si->xoff+1 || x >= si->xoff+si->width-2))
continue;
int color = si->color;
/* Alter the color if this is a place where we want to
* draw a window. We check that we are in the inner part of the
* skyscraper, so that windows are far from the borders. */
if (si->windows &&
x > si->xoff+1 &&
x < si->xoff+si->width-2 &&
y > endy+1 &&
y < starty-1)
{
/* Calculate the x,y position relative to the start of
* the window area. */
int relx = x - (si->xoff+1);
int rely = y - (endy+1);
/* Note that we want the windows to be two pixels wide
* but just one pixel tall, because terminal "pixels"
* (characters) are not square. */
if (relx/2 % 2 && rely % 2) {
do {
color = 1 + rand() % 2;
} while (color == si->color);
/* Except we want adjacent pixels creating the same
* window to be the same color. */
if (relx % 2) color = lwGetPixel(canvas,x-1,y);
}
}
lwDrawPixel(canvas,x,y,color);
}
}
}
/* Generate a skyline inspired by the parallax backgrounds of 8 bit games. */
void generateSkyline(lwCanvas *canvas) {
struct skyscraper si;
/* First draw the background skyscraper without windows, using the
* two different grays. We use two passes to make sure that the lighter
* ones are always in the background. */
for (int color = 2; color >= 1; color--) {
si.color = color;
for (int offset = -10; offset < canvas->width;) {
offset += rand() % 8;
si.xoff = offset;
si.width = 10 + rand()%9;
if (color == 2)
si.height = canvas->height/2 + rand()%canvas->height/2;
else
si.height = canvas->height/2 + rand()%canvas->height/3;
si.windows = 0;
generateSkyscraper(canvas, &si);
if (color == 2)
offset += si.width/2;
else
offset += si.width+1;
}
}
/* Now draw the foreground skyscraper with the windows. */
si.color = 0;
for (int offset = -10; offset < canvas->width;) {
offset += rand() % 8;
si.xoff = offset;
si.width = 5 + rand()%14;
if (si.width % 4) si.width += (si.width % 3);
si.height = canvas->height/3 + rand()%canvas->height/2;
si.windows = 1;
generateSkyscraper(canvas, &si);
offset += si.width+5;
}
}
/* The LOLWUT 6 command:
*
* LOLWUT [columns] [rows]
*
* By default the command uses 80 columns, 40 squares per row
* per column.
*/
void lolwut6Command(client *c) {
long cols = 80;
long rows = 20;
/* Parse the optional arguments if any. */
if (c->argc > 1 &&
getLongFromObjectOrReply(c,c->argv[1],&cols,NULL) != C_OK)
return;
if (c->argc > 2 &&
getLongFromObjectOrReply(c,c->argv[2],&rows,NULL) != C_OK)
return;
/* Limits. We want LOLWUT to be always reasonably fast and cheap to execute
* so we have maximum number of columns, rows, and output resulution. */
if (cols < 1) cols = 1;
if (cols > 1000) cols = 1000;
if (rows < 1) rows = 1;
if (rows > 1000) rows = 1000;
/* Generate the city skyline and reply. */
lwCanvas *canvas = lwCreateCanvas(cols,rows,3);
generateSkyline(canvas);
sds rendered = renderCanvas(canvas);
rendered = sdscat(rendered,
"\nDedicated to the 8 bit game developers of past and present.\n"
"Original 8 bit image from Plaguemon by hikikomori. Redis ver. ");
rendered = sdscat(rendered,REDIS_VERSION);
rendered = sdscatlen(rendered,"\n",1);
addReplyVerbatim(c,rendered,sdslen(rendered),"txt");
sdsfree(rendered);
lwFreeCanvas(canvas);
}