vhsh 1.0.0b1

VideoHomeShader: A demo tool for digitally assisted analog vjaying

VHSh

Video Home Shader: A demo tool for digitally assisted analog vjaying

Installation

uv is the recommended way of installing

• macOS

  brew install uv
  uv tool update-shell
  

• Ubuntu

  curl -LsSf https://astral.sh/uv/install.sh | sh
  # for audio support
  sudo apt install portaudio19-dev
  uv tool update-shell
  

Or refer to its documentation.

Then you can install VHSh:

uv tool install vhsh[all]

The [all] installs the full feature set. If you want to manually select certain features, for example because you don't need audio or MIDI, you can list them in the brackers (multiple are possible):

• automatic reload on file change: vhsh[watch]
• MIDI support: vhsh[midi]
• audio support: vhsh[audio]
• import from Shadertoy: vhsh[import]
• everyting: vhsh[all]

Usage

To open a shader file, a scene, use the run command:

vhsh run myscene.glsl

When run without any file argument, the default scenes will be loaded and a testcard.glsl scene will be created in the current directory.

If you pass multiple shader files, you can switch between them in the tool. To open all files GLSL files in a given folder, use my_shader_folder/*.glsl.

If installed with [watch], the shader files will be watched for changes and automatically reloaded.

If installed with [audio] You can pass --mic to enable microphone input. See Builin Parameters.

To toggle the UI, press <tab>.

MIDI Support

When installed using [midi] flag, VHSh will listen to incoming MIDI messages and allow you to map parameters to MIDI controls. How to assign uniform mappings is described in Custom Parameters.

There are also a couple of system controls, like switching scenes, that can be mapped to buttons as well. Such a mapping is defined as a TOML file and passed via --midi-mapping.

[scene]
prev = 58  # switch to next scene
next = 59  # switch to previous scene

[preset]
prev = 61  # switch to next preset
next = 62  # switch to previous preset
save = 60  # save current parameter values to a new preset

[ui]
toggle = 45  # show/hide parameter control window

[parameter.time]
toggle = 41

Sensible mappings for various controls are supplied in midi_mappings/.

Writing Shaders for Video Home Shader

Scene format version: 1

Video Home Shader supplies you with a 2D canvas to draw into using an OpenGL fragment shader. It is run once for every pixel on the screen and determines it's color.

Berfore your shader file is run, a preamble is prepended to the source code. It defines

OpenGL Version 330 core

so you just need to supply a main function and set the output color FragColor as an RGBA vec4 with floats between 0 and 1 (0., 0., 0., 1.) being black).

void main() {
    FragColor = vec4(0.8, 0.2, 0.2, 1.0);
}

Builtin Parameters

You can use the following built-in parameters, that are pre-defined in the preamble:

• vec2 Resolution: width and height of the window in pixels. This can be used to calculate normalized screen space coordinates like

  vec2 pos = gl_FragCoord.xy / Resolution;
  

  where pos.xy will now have the current pixel's coordinates between [-1, 1]^2

• float Time: Seconds since the program start. This can be used to animate things. For example

  vec4 color = vec4((sin(2. * 3.14 * Time * ) + 1.) / 2., 0., 0., 1.);
  

  will create a red pulsing effect with one pulse per second.

• float[7] Microphone: If started with --mic, this is a float array that gives you volume per frequency band normalized over the last 5s.

  Index	Range		Description
  Microphone[0]	0 Hz	60 Hz	Rumble
  Microphone[1]	60 Hz	250 Hz	Low End
  Microphone[2]	250 Hz	500 Hz	Low Mids
  Microphone[3]	500 Hz	2 kHz	Mids
  Microphone[4]	2 KHz	6 kHz	High Mids
  Microphone[5]	6 kHz	8 kHz	Highs
  Microphone[6]	> 8 KHz		Air

Custom Parameters

You can define custom parameters to vary directly in the code, and the user interface to manipulate them will be generated automatically. Use the uniform keyword followed by a type (bool, int, float, vec2, vec3, vec4) and a name.

uniform bool override_red; // =False
uniform int n_max; // =10 [1,200] #0
uniform float scale; // =1. [0.,2.] #16
uniform vec2 origin; // =(0.,0.) [-2.,-2.]
uniform vec3 dir; // =(1.,0.,0.) [-1.,-1.]
uniform vec4 base_color; // <color> =(1.,1.,0.,1.)

Using a special syntax in a comment on the same line, you can define the the following uniform control properties:

• =VALUE default value
• [MIN,MAX,STEP] range (where STEP is optional).
• <WIDGET> special UI widget
  • <color> on vec3 for a RGB and on vec4 for a RGBA color picker
  • <log> for a logarithmic scale
  • <drag> for controling the UI widget with dragging (instead of slider)
• #MIDI MIDI control ID. To bind a MIDI control to a uniform, for example: #16.

The have to be defined in the order

uniform type name; // <WIDGET> =VALUE [MIN,MAX,STEP] #MIDI

and the values (and ranges) may not contain whitespace. Each individual part (widget, value, range) is optional and they can be mixed and matched as desired, as long as the order of appearance is correct. As generally with GLSL, it is also important to strictly match the types. Supplying a float as default value for an int will not work. There may be no other text in the comment. All vector types have to be supplied as a comma-separated list of floats, enclosed by parentheses (1.,2.,3.). One can only supply a scalar range that applies along all dimensions.

// syntax error
uniform float scale; // =1
// OK
uniform float scale; // =1.

// syntax error
uniform vec2 origin; // =[0.,0.]
// OK
uniform vec2 origin; // =(0.,0.)

// syntax error
uniform vec3 dir; // [[0.,1.],[0.,1.],[0.,5.]]
// OK
uniform vec3 dir; // [0.,1.]
dir.z *= 5;

By using ctrl+click, one can directly edit the values with keyboard input.

If two consecutive uniforms share a common prefix in their name (like box_size and box_color), they will be grouped together.

Presets

You can save the current uniform values as the new =DEFAULT parameter in your loaded shader source file by clicking Save when the currently selected preset. is <current>.

Furthermore, you can store multiple sets of parameters (including different) default values, ranges, MIDI mappings etc.) as presets. To save a new preset, enter the name in the Name field and click New Preset. The shader source file will be modified by prepending the unform and metadata defintions with a special comment prefix (/// ). Since all those lines will deleted and rewritten on save, be sure to not use triple-slashes for other reasons. Each preset is preceeded by its name.

/// // My New Preset
/// uniform bool override_red; // =False
/// uniform int n_max; // =10 [1,200] #0
/// uniform float scale; // =1. [0.,2.] #16
/// uniform vec2 origin; // =(0.,0.) [-2.,-2.]
/// uniform vec3 dir; // =(1.,0.,0.) [-1.,-1.]
/// uniform vec4 base_color; // <color> =(1.,1.,0.,1.)

You can add, modify and delete these comment blocks with you're text editor as well.

To update an existing preset, select it, adjust the parameter values and click Save. The current paremeter values will be written to the default values of the currently selected preset.

Metadata

Metadata for a scene can be recorded in the form of

/// @key value

Currently supported metadata fields:

• version (int): Used to ensure scene format and VHSh version are compatible. Will emit a warning when loading a scene with missing or incompatible version. Missing version will be updated when saving a preset.
• name (str): Can be used to set a custom scene name. If omitted, the file name will be cleaned up and title-cased.
• author (str): Credit the author.

Scene Format Version History

@version 1

• Introduced version number
• Changed system uniforms from u_Time to Time etc.
• Introduced metadata, keys: version, name, author

Importing Scenes

Shadertoy

[!WARNING] The Shadertoy API usage was exceeded and the included key does not work..

You can import scenes from [Shadertoy.com][shaderdoy].

vhsh import https://www.shadertoy.com/view/ftt3R7

To use your own API key (available from Shadertoy Apps), set $VHSH_API_KEY_SHADERTOY:

VHSH_API_KEY_SHADERTOY=abc123 vhsh import https://www.shadertoy.com/view/ftt3R7

Development

You can run vhsh with the -v/--verbose (before the sub-command), to enable debug logging.

VHSh uses the Astral toolchain: uv for dependcy-management and packaging, ruff for linting and formatting, and ty as language server and type checker.

Setup

On macOS, install uv via, or refer to its documentation:

brew install uv

Then create a virtual environment and run the test suite.

uv sync --dev --extra all
uv run ruff check
uv run ty check
uv run vulture
uv run pytest

To ignore formatting changes etc for git-blame, configure

git config blame.ignoreRevsFile .git-blame-ignore-revs

Publish

To publish the package to PyPI, setup the credentials for PyPI in .env

UV_PUBLISH_TOKEN=pypi-...

Create a SemVer git tag, as the package version is dynmically determined by the latest git tag. Use uv to build and publish wheels.

git tag -a v1.23.42

set -a; source .env; set +a

uv build
uv publish

Resources

If you're seeing a message like

2024-10-02 22:10:15.567 Python\[75271:1828570\] ApplePersistenceIgnoreState:
Existing state will not be touched. New state will be written to
/var/folders/2b/gfpmffr15n9cwdy6_44mhy8r0000gn/T/org.python.python.savedState

run the following to get rid of it:

defaults write org.python.python ApplePersistenceIgnoreState NO

Shader Development

• https://iquilezles.org/articles/
• https://docs.gl/sl4/
• https://www.youtube.com/watch?v=f4s1h2YETNY
• http://dev.thi.ng/gradients/

VHSh Development

• https://pthom.github.io/imgui_manual_online/manual/imgui_manual.html
• https://pyopengl.sourceforge.net/documentation/manual-3.0/
• https://regex101.com
• https://github.com/pyimgui/pyimgui/blob/master/doc/examples/testwindow.py
• https://mido.readthedocs.io/en/stable/intro.html