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diff --git a/_site/log/matrix-digital-rain/index.html b/_site/log/matrix-digital-rain/index.html index b428f9e..7c8c659 100644 --- a/_site/log/matrix-digital-rain/index.html +++ b/_site/log/matrix-digital-rain/index.html @@ -2,12 +2,12 @@ <html> <head> <meta charset="utf-8"> - <title>Matrix Rain: 2025 refactor</title> + <title>Recreating the Matrix rain with ANSI escape sequences</title> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> - <title>Matrix Rain: 2025 refactor</title> + <title>Recreating the Matrix rain with ANSI escape sequences</title> <link rel="stylesheet" href="/assets/css/main.css"> <link rel="stylesheet" href="/assets/css/skeleton.css"> </head> @@ -41,34 +41,141 @@ <main> <div class="container"> <div class="container-2"> - <h2 class="center" id="title">MATRIX RAIN: 2025 REFACTOR</h2> + <h2 class="center" id="title">RECREATING THE MATRIX RAIN WITH ANSI ESCAPE SEQUENCES</h2> <h6 class="center">21 DECEMBER 2025</h5> <br> - <div class="twocol justify"><p>Unicode support added. ASCII + Katakana working:</p> + <div class="twocol justify"><p>My 2022 implementation of the Matrix rain had too many loose ends. Unicode +support was inflexible: the character set had to be a single contiguous block +with no way to mix ASCII with something like Katakana; Phosphor decay level was +stored in a dedicated array–still don’t understand why I did that when I had +already used bit-packing for the RGB channels; The algorithm was difficult to +decipher. The 2022 version worked, but that’s not the same thing as correct.</p> + +<p>I began by placing the decay factor in the MSB of the 4-byte RGB value. The PD +value plays a somewhat analogous role to an alpha channel in that both +influence transparency. However, they work very differently. So, I avoided +labelling it A so as not to cause confusion:</p> + +<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>enum { + R, /* Red */ + G, /* Green */ + B, /* Blue */ + PD /* Phosphor decay level */ +}; + +typedef union color_tag { + uint32_t value; + unsigned char color[4]; +} color; +</code></pre></div></div> + +<p>The decision to use union over more portable bit twiddling was made three years +ago, as I recall, for readability. Seeing as all my systems are little-endian, +this is unlikely to cause any trouble. Besides, if union is never to be used, +why is it in the language anyway?</p> + +<p>The blend() function, which emulates the dim afterglow of Phosphor by eroding +the RGB channels towards the background, with minor refactoring, remains as +elegant as it did three years ago:</p> + +<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>#define DECAY_MPLIER 2 + +static inline void blend(matrix *mat, + size_t row, size_t col) +{ + unsigned char *color; + + color = mat->rgb[index(mat, row, col)].color; + color[R] = color[R] - (color[R] - RGB_BG_RED) / DECAY_MPLIER; + color[G] = color[G] - (color[G] - RGB_BG_GRN) / DECAY_MPLIER; + color[B] = color[B] - (color[B] - RGB_BG_BLU) / DECAY_MPLIER; +} +</code></pre></div></div> + +<p>While the memory inefficiency of Phosphor decay was a technical oversight I +hadn’t noticed, the limitation around mixing nonadjacent Unicode blocks was a +nagging concern even three years ago. So, a fix was long overdue.</p> + +<p>In the new version, I introduced an array that enables a user to add as +many Unicode blocks as they want. The insert_code() function picks a block +from it at random, and then picks a character from that block at random:</p> + +<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>#define UNICODE(min, max) (((uint64_t)max << 32) | min) + +static uint64_t glyphs[] = { + UNICODE(0x0021, 0x007E), /* ASCII */ + UNICODE(0xFF65, 0xFF9F), /* Half-width Katakana */ +}; + +static uint8_t glyphlen = (sizeof glyphs) / (sizeof glyphs[0]); + +static inline void insert_code(matrix *mat, + size_t row, size_t col) +{ + uint64_t block; + uint32_t unicode_min, unicode_max; + + block = glyphs[(rand() % glyphlen)]; + unicode_min = (uint32_t)block; + unicode_max = (uint32_t)(block >> 32); + + mat->code[index(mat, row, col)] = rand() + % (unicode_max - unicode_min) + + unicode_min; +} +</code></pre></div></div> + +<p>The Unicode blocks are stored in 8-byte containers: the low four bytes form the +first codepoint and the high four bytes the last. Here, I chose bitwise +operations over unions because, first and foremost, the operations themselves +are trivial and idiomatic, and the UNICODE() macro simplifies the management of +charsets.</p> + +<p>The init_term() function is the arbiter of this zero-dependency software. It +prepares the graphical environment so that I can interact with it via ANSI +escape codes instead of unnecessary layers of abstraction:</p> + +<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>static inline int init_term(const struct winsize *ws) +{ + struct termios ta; + + if (tcgetattr(STDIN_FILENO, &ta) == 0) { + ta.c_lflag &= ~ECHO; + if (tcsetattr(STDIN_FILENO, TCSANOW, &ta) == 0) { + wprintf(L"\x1b[48;2;%d;%d;%dm", + RGB_BG_RED, RGB_BG_GRN, RGB_BG_BLU); + wprintf(L"%s", ANSI_FONT_BOLD); + wprintf(L"%s", ANSI_CRSR_HIDE); + wprintf(L"%s", ANSI_CRSR_RESET); + wprintf(L"%s", ANSI_SCRN_CLEAR); + setvbuf(stdout, 0, _IOFBF, 0); + ioctl(STDOUT_FILENO, TIOCGWINSZ, ws); + return 1; + } + } + return 0; +} +</code></pre></div></div> + +<p>insert_code() seeds the Matrix, blend() creates the old monochrome CRT display +nostalgia, and ANSI control sequences paint the screen. The result is a digital +rain that captures the original Matrix aesthetic with high visual fidelity:</p> + +<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>$ cc -O3 main.c -o matrix +$ ./matrix +</code></pre></div></div> <video style="max-width:100%;" controls="" poster="poster.png"> <source src="matrix.mp4" type="video/mp4" /> </video> -<p>Algorithm notes: mat.col[] = shuffled column indices, mat.row[] = last row per -column. shuffle() sets working set, main loop draws columns via index i (line -333), swap() rotates set.</p> +<p>There was no cause to measure the program’s performance characteristics +precisely; it’s gentle on the CPU. On my ThinkPad T490 running OpenBSD, which +has a resolution of 1920x1080, it uses about 2-3% of the CPU, with occasional +jumps of up to about 8%; the cores remain silent, the fans don’t whir, the rain +falls in quiet.</p> -<p>Phosphor decay moved to LSB of RGB union. Should have done this originally.</p> - -<p>RGB/PD union stays. Little-endian machine, portability not a concern.</p> - -<p>Charset via UNICODE(min, max) macro - packs range into uint64, insert_code() -unpacks and selects random char.</p> - -<p>Half-width Katakana (U+FF61-U+FF9F) for column alignment.</p> - -<p>Removed license, automake files. Build: cc -O3 main.c -o matrix</p> - -<p>Performance: 2% CPU, OpenBSD, T490.</p> - -<p>Commit: -<a href="https://git.asciimx.com/matrix-digital-rain/commit/?id=03f8d87ba7c2e46bd3f3cc4c772fb3a2ac740c92">03f8d87</a></p> +<p>Files: <a href="source.tar.gz">source.tar.gz</a></p> </div> <p class="post-author right">by W. D. Sadeep Madurange</p> |