ematrix

ematrix is a highly customizable digital rain effect.

Written in C99 using OpenGL 3.3 (GLAD), GLFW and stb_image.h.
Own files of ematrix (files not located in src/lib/ directory) is distributed under The MIT License (See LICENSE for details).

Compiling

• Install:
  • C99-compliant compiler and linker
  • GNU make
  • GLFW
• Open a terminal in this directory and run make. The executable will be located in the build/ directory.
  • Alternatively, run make test to compile and run ematrix immediately.

About the effect

The effect utilizes glyphs provided by a font (See Fonts) to render the rain (matrix of characters).
Each character glyph changes randomly. Each character has brightness counter that decreases over time.
A drop moves down each column of the rain. It increases the brightness counter of the characters it touches. Characters currently being touched by a drop are active and use separate layer of color map (See Color map).
Once a drop reaches the bottom edge of the window, it disappears for a random time before jumping to the top of window.

Configuration

ematrix is configured using key=value options.

You can pass options directly via the command-line argument -key=value, or specify a configuration file containing options using the path/to/config argument.
Note: You can NOT add spaces after the equation mark (=).

List of Options

Key	Type	Description	Default	Min	Max
Log	int	Logging verbosity level. 0: none, 1: errors, 2: errors+version, 3: verbose.	2	0	3
Screen	int index	The index of the screen to open in fullscreen. If set to -1, fullscreen is disabled.	-1	-1	32768
ScreenW	int pixels	Fullscreen width (0 for default).	0	0	32768
ScreenH	int pixels	Fullscreen height (0 for default).	0	0	32768
Resize	bool	If enabled, allows resizing the window and toggling fullscreen via the KeyFullscreen keybind.	1	0	1
AutoIcon	bool	If enabled, the fullscreen window will iconify when you click on another screen.	0	0	1
HideMouse	bool	If enabled, the mouse cursor will be hidden when clicked. It can be shown again via KeyShowMouse keybind.	0	0	1
W	int pixels	Window width.	800	1	32768
H	int pixels	Window height.	600	1	32768
Title	string	Window title.	"ematrix"
CharSize	int pixels	Size of one character.	20	1	32768
Border	int pixels	Empty gap from window borders.	4	0	32768
Stretch	bool	Allows glyphs to be stretched for an ideal fit.	1	0	1
VSync	int	If set to 0, VSync is disabled. other values act as a divisor for the monitor's frame rate. Can be ignored if the GPU does not support VSync.	1	0	32768
Font	string path	Path to a font file (PNG MSDF). See Fonts.	"embed://1.png"
FontNum	int	The number of glyphs contained in the font file. See Fonts.	57	1	32768
FontCols	int	The number of columns the glyphs are grouped into. See Fonts.	8	1	32768
FontRows	int	The number of rows the glyphs are grouped into. See Fonts.	8	1	32768
Seed	int	Seed of random generator. If set to zero, seed is determined by current time and PID.	0	0	INT_MAX
RandMin	int frames	Minimum time between glyph randomization.	200	1	32768
RandMax	int frames	Maximum time between glyph randomization.	400	1	32768
RandPow	int	Maximum steps of pow'ing.	8	0	32768
RandMul	int frames	Each pow'ing step the time is multiplied by this.	5	1	32768
RandDiv	int frames	Each pow'ing step the time is divided by this.	4	1	32768
DropMin	int frames	Minimum period between falling drops.	200	1	32768
DropMax	int frames	Maximum period between falling drops.	400	1	32768
OnlyInt	bool	If enabled, the drop period will be rounded to an integer ratio.	1	0	1
Trail	int 0.01%	Average trail length relative to window height. Faster drops have longer trails.	8000	0	32768
MinTrail	int chars	Minimum trail length.	6	0	32768
Gauss	int pixels	Gaussian blur factor.	12	1	256
Linear	int pixels	Linear blur factor.	3	1	32768
BlurAlpha	int 0.01%	The brightness of the blur.	5000	0	INT_MAX
BlurPow	int 0.01%	The power applied to the blur. Higher values result in a sharper blur.	10000	0	INT_MAX
Noise	int 0.01%	The strength of blur noise.	2000	0	10000
NoisePow	int 0.01%	The power applied to the blur noise.	20000	0	32768
ColorX	int 0.01%	X resolution of the color map.	1	1	32
ColorY	int 0.01%	Y resolution of the color map.	1	1	32
ColorZ	int 0.01%	Z resolution of the color map.	1	1	32
R{X}.{Y}.{Z}	int	Red component of the color map pixel. See Color map.		0	255
G{X}.{Y}.{Z}	int	Green component of the color map pixel. See Color map.		0	255
B{X}.{Y}.{Z}	int	Blue component of the color map pixel. See Color map.		0	255
Hex{X}.{Y}.{Z}	hex color	Color map pixel. See Color map.
KeyFullscreen	int GLFW key	Keybinding for fullscreen mode.	300 (F11)
KeyShowMouse	int GLFW key	Keybinding to show the mouse (which can be hidden via HideMouse).	256 (Escape)
KeyQuit	int GLFW key	Keybinding to quit the application.	81 (Q)
Echo	string	Command. Prints value to stdout.
Include	string path	Command. Parses the config file.
TryInclude	string path	Command. Parses the config file only if it exists.

All keys are case-insensitive. You can also add spaces and dashes (-) anywhere within a key.
Boolean fields are represented as integers (0 or 1) rather than false or true.
Paths prefixed with ~/ are automatically resolved to the current user's home directory.
Default values, MAX_COLOR_RES_* and other constants can be modified in src/config.c.

Color map

The color map is a ColorMapResX * ColorMapResY * ColorMapResZ 3D texture used to define character colors.
Its X and Y dimensions match the character position, and the Z dimension represents brightness. An extra Z layer is used for active characters.

Default color map:

ColorResX=1
ColorResY=1
ColorResZ=1
Hex0.0.0=30D018
Hex0.0.1=D0FFC0 # Active characters

Fonts

embed/1.png

Font is a PNG image that stores MSDF (Multi-channel Signed Distance Field).
Glyphs should be laid out from left to right and top to bottom.
With a font you should provide the total number of glyphs, columns and rows.
Unused image space (free from glyphs) can contain anything.

Code structure

• src/: C sources of the project.
  • src/ematrix.c: ematrix itself.
  • src/config.c: Some configurable constants.
  • src/lib/: External libraries.
• embed/: All files inside are embedded into the executable during build.