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diff --git a/_projects/matrix-digital-rain.md b/_projects/matrix-digital-rain.md index f9a1a22..35a3d97 100644 --- a/_projects/matrix-digital-rain.md +++ b/_projects/matrix-digital-rain.md @@ -5,7 +5,8 @@ thumbnail: thumb.png layout: post --- -The famous digital rain from The Matrix, implemented in C. +"All I see is blonde, brunette, red head." The iconic digital rain from The +Matrix, implemented in C, without dependencies (not even ncurses). <video style="max-width:100%;" controls="" poster="thumb.png"> <source src="matrix.mp4" type="video/mp4"> @@ -13,17 +14,94 @@ The famous digital rain from The Matrix, implemented in C. This project is a fork of Domsson's beautiful <a href="https://github.com/domsson/fakesteak" class="external" target="_blank" -rel="noopener noreferrer">Fakesteak</a>. +rel="noopener noreferrer">Fakesteak</a>. Use the following commands to compile +and run the program: -There are three color settings: head, tail, and background. They are configured -by setting the 24-bit RGB channels using `COLOR_*_RED`, `COLOR_*_GRN`, and -`COLOR_*_BLU` definitions. The ghosting effect of old monochrome screens is -achieved by scaling the RGB channels. This results in a rain effect that -closely resembles the original from the first Matrix movie. +``` +$ cc -O3 main.c -o matrix +$ ./matrix +``` -In addition, this implementation supports UTF-32 character sets. The -`UNICODE_MIN` and `UNICODE_MAX` controls the Unicode block used. For -instance, setting them to `0x30A1` and `0x30F6` rains Katakana: +While I loved Domsson's take on the +digital rain, what blew my mind was the minimalistic elegance of his code. As I +carefully examined it, I thought about what it might take to recreate the +original digital rain from the first Matrix movie with it. The challenge is +adding these features without destroying fakesteak's elegance. + +## How does it work? + +The `matrix` struct makes use of three 2D arrays to encode the Matrix: the +`code` array for 32-bit Unicode characters, the `rgb` array for 24-bit RGB +values of the character (foreground color), and the `shade` array for the +degree of transparency of the character to simulate the ghosting effect of old +monochrome displays. The dimensions of these arrays depend on the size of the +terminal screen. Each slot in the array corresponds to a cursor position on the +screen. + +The ghosting effect, which is arguably the crowning feature of my version, is +implemented by carefully scaling and mixing the RGB channels: + +``` +static void mat_shade(matrix *mat, size_t row, size_t col) +{ + unsigned char *color; + color = mat->rgb[mat_idx(mat, row, col)].color; + color[R] = color[R] - (color[R] - COLOR_BG_RED) / 2; + color[G] = color[G] - (color[G] - COLOR_BG_GRN) / 2; + color[B] = color[B] - (color[B] - COLOR_BG_BLU) / 2; +} +``` + +The above algorithm achieves transparency by iteratively bringing the +foreground color closer to the background color with each pass of the rain. +This approach offers multiple advantages, such as simpler and more natural +color configuration (background, foreground, and the color of the first drop) +that lends itself well to Unix ricing, and of course, recreates The Matrix rain +with high fidelity. + +Rather than heavy-weight graphics tool kits, we use ANSI escape codes to +control the terminal screen. It's the effective use of the ANSI escape codes +that greatly contributes to the minimalism of the solution: + +``` +static void term_print(const matrix *mat, size_t row, size_t col) +{ + size_t idx; + idx = mat_idx(mat, row, col); + wprintf(L"\x1b[%d;%dH\x1b[38;2;%d;%d;%dm%lc", + row, col, + mat->rgb[idx].color[R], + mat->rgb[idx].color[G], + mat->rgb[idx].color[B], + mat->code[idx]); +} +``` + +Finally, the glitch effect is controlled by the following code: + +``` +if (mat.row[i] > 0 && rand() % 6 == 0) { + j = rand() % mat.row[i]; + if (mat.code[mat_idx(&mat, j, mat.col[i])] != ' ') { + mat_put_code(&mat, j, mat.col[i]); + term_print(&mat, j, mat.col[i]); + } +} +``` + +The above code causes glitches in the Matrix with a probablity of 1/6. + +## Customizing the rain + +While you can customize almost any aspect of the rain including its speed, +glitch frequency, and the density of the rain, the most useful settings for +ricing are the color scheme and the character set used for the rain. + +There are three color settings: the head, the tail, and the background. They +are configured by setting the `COLOR_*_RED`, `COLOR_*_GRN`, and `COLOR_*_BLU` +definitions in main.c. The `UNICODE_MIN` and `UNICODE_MAX` values control the +Unicode block used. For instance, setting them to `0x30A1` and `0x30F6` rains +Katakana code points: <img style="width: 100%;" src="katakana.png" /> |