ShaderShark
ShaderShark is an OpenGL/X11 application for GNU/Linux consisting of a single window that shows simple 3D scene of a textured rectangle with applied vertex and fragment shaders (GLSL).
Features
- load textures in various formats (PNG, JPEG etc.)
- rotations and movement in the 3D space
- textures with alpha-channel (transparent, irregular shape)
- fully controllable using keyboard
- automatically reloads textures and shaders
- configurable background color
- can be embedded in another X11 window
There are no buttons, no text editors, just the 3D scene. The user is expected to use his own favourite text editor to edit the shaders and just save the file – the save operation from the external editor triggers reload of the shader or texture in ShaderShark.
Roadmap and ideas
- modular design and API to allow optional complexity
- abstract layer for loading textures from various sources (not only image formats but also e.g. camera or other X11 window)
- optional continuous mode (render the scene not only when shaders/textures change, but continually like games do and provide time variable and mouse location to the shaders)
- multiple rectangles (to show multiple texture/shader combinations at once)
- other objects in the 3D scene (floor, background, lights etc.)
- 3D sound
- stereoscopic mode
- batch mode (apply fragment shader as a filter to images)
- other input methods and devices (like 3D mouse)
- render text files using bitmap fonts
- visualize binary files
- …
This tool was created for our internal purposes and is published as is without any guarantees. In the future, it might become a product (however still free software, of course) with regular releases, but we are not there yet.
Usage
Environment variables:
-
SHADER_SHARK_DATA_DIR– should point to a place whereshadersandtexturesdirectories are located; is used to load defaults when no shaders/textures are specified; can point to the ShaderShark source directory -
DISPLAY– standard X11 variable; can be used to run the application on different display; usually keep default that is already set
Extended attributes:
-
shader-shark.texture.mag-filter– can be set on the texture file to specify theGL_TEXTURE_MAX_FILTERi.e. method of scaling smaller texture to larger surface; possible values are:nearest(sharp, pixelated) andlinear(blurry, soft) -
shader-shark.texture.min-filter– same, just forGL_TEXTURE_MIN_FILTER -
shader-shark.texture.scale– normal value is1.or empty, but if the texture was upscaled e.g. from 320×240 to 640×480, we set this attribute to2.0; this value is then passed to the shaders, so they will know the original/logical texture dimensions; this is useful for drawing lines or grids that should fit the gaps between the original pixels
Command line arguments:
-
--texture– texture to load, e.g. PNG or JPEG file -
--shader– first argument is shader type (vertexorfragment) and second one is the file name; when missing, default shader is loaded -
--background-color– RGB color code in hexadecimal, like147258,333333,345678etc. -
--root-window– specify an X11 window ID (as decimal or hexadecimal integer) to embed ShaderShark into an existing window
Controls:
- move: ed up/down m,jkui l.
- turn: sf left/right tg
- roll: wr
- zoom: mouse-wheel
- reset view: x mouse-back
- full screen: F11 y
- exit: q escape mouse-forward
ShaderShark is controlled mainly by the keyboard. It expects fingers on the home row, thus it is ESDF not WASD. Left hand does move forward/backward, rotate left/right and roll left/right. Right hand does move left/right (three different speeds) and move up/down.
Basic usage is just:
shader-shark --texture "some.png" --shader fragment "hello.frag"
Bash-completion script is provided.
It is not necessary to restart ShaderShark
to reload a texture or a shader – it monitors the files
(using inotify) and reloads them when needed.
It reacts to the CLOSE_WRITE
so when the editor finishes writing, ShaderShark loads new content.
(editors that delete original file and create a new one
will not work with current version of ShaderShark – use other editor
or e.g. cat some-texture.png > temp.png)
Common workflow is to open ShaderShark and text editor windows side by side and have some fun with GLSL when having live preview of what tha shader does.
Video
The first demo that shows usage of ShaderShark: keyboard and mouse controls, loading textures, applying shaders, error handling, writing simple scanline and phosphor shaders, editing properties of a texture (xattr), ideas for further development.
- shader-shark_video-01_av1.webm (113 MB)
- shader-shark_video-01_hevc.mp4 (148 MB)
Extended attributes editor used in the video: rozsirene-atributy (configuration script: xattr-editor.sh).
Graphics utilities are free software © 2023 GlobalCode