https://github.com/snsinfu/frag
Stateful GLSL fragment shader runner
https://github.com/snsinfu/frag
cellular-automata glsl opengl
Last synced: 2 days ago
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Stateful GLSL fragment shader runner
- Host: GitHub
- URL: https://github.com/snsinfu/frag
- Owner: snsinfu
- License: mit
- Created: 2020-08-06T15:30:07.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2021-06-01T15:24:38.000Z (over 4 years ago)
- Last Synced: 2024-06-21T15:48:54.238Z (over 1 year ago)
- Topics: cellular-automata, glsl, opengl
- Language: Go
- Homepage:
- Size: 4 MB
- Stars: 2
- Watchers: 3
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
Awesome Lists containing this project
README
# frag: GLSL fragment shader runner
[![Build Status][build-badge]][build-url]
[![Boost License][license-badge]][license-url]
`frag` is a GUI program that runs GLSL fragment shader on a 2D canvas. The
shader has access to mouse position, time and previous frame as a texture. So
you can render stateful animation like Conway's Game of Life!
[![Game of Life][game-of-life-screenshot]][game-of-life-code]
[build-badge]: https://github.com/snsinfu/frag/workflows/build/badge.svg
[build-url]: https://github.com/snsinfu/frag/actions?query=workflow%3Abuild
[license-badge]: https://img.shields.io/badge/license-MIT-blue.svg
[license-url]: ./LICENSE.txt
[game-of-life-screenshot]: ./examples/screenshots/game_of_life.png
[game-of-life-code]: ./examples/game_of_life.frag
- [Build](#build)
- [Usage](#usage)
- [License](#license)
See [examples directory](./examples) for example shaders!
## Build
`frag` is written in Go. Use the following commands to build an executable:
```console
$ git clone https://github.com/snsinfu/frag.git
$ cd frag
$ go build -o frag ./main
```
On linux you need Xorg header files. Install `xorg-dev` if you use Ubuntu or
Debian.
## Usage
`frag` accepts filename of a fragment shader source as an argument. Try running
an example:
```console
$ frag examples/gradient_animation.frag
```
The source is the standard GLSL shader with optional pragma directives:
```glsl
#version 330
#pragma frag:canvas 1280 800
#pragma frag:scale 1.0
#pragma frag:fps 60.0
uniform float time;
in vec2 texCoord;
out vec4 fragColor;
void main() {
fragColor.r = 0.75 + 0.25 * sin(2.0 * texCoord.s + time);
fragColor.g = 0.75 + 0.25 * sin(2.0 * texCoord.t + time);
fragColor.b = 0.75 + 0.25 * cos(2.0 * texCoord.t + time);
}
```
### Uniforms
These `uniform`s are provided:
| type | name | description |
|-----------|------------|----------------------------------------------|
| vec2 | resolution | Size of canvas in pixels. |
| vec2 | mouse | Mouse position in pixels. |
| float | time | Number of seconds from program start. |
| int | frame | Incremented on each frame. Starts from zero. |
| sampler2D | sampler | Texture holding the previous frame. |
`texture(sampler, texCoord)` gives the color of the pixel in the previous frame.
To get neighboring pixels, use `texCoord + vec2(+1, -1) / resolution` etc. for
the texture coordinates.
### Attributes
Input attribute:
| type | name | description |
|-----------|--------------|----------------------------------------------|
| vec2 | texCoord | Normalized texture coordinates of the pixel. |
Fragment output:
| type | name | description |
|-----------|------------|----------------------------------------------|
| vec4 | fragColor | Color of the pixel. |
The `fragColor.a` component is not used for rendering. The shader program may
use this component for whatever purpose.
### Pragmas
| pragma | description |
|:-----------------------------|:-------------------------------------------|
| frag:canvas _width_ _height_ | Size of canvas in pixels. |
| frag:scale _scale_ | Canvas is scaled on screen by this factor. |
| frag:fps _fps_ | Maximum frames per second. |
| frag:wrap _mode_ | Wrapping mode when sampling from canvas. `repeat`, `mirror` or `clamp`. |
| frag:bits _bits_ | Bit depth of pixel. 32 or 64. |
The canvas size etc. can also be set via command-line options:
```console
$ frag --canvas 15x15 --scale 40 --fps 5 examples/gradient_animation.frag
```
See `frag --help` for the list of options.
## License
MIT License.