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Oct 31, 2015
Jun 20, 2015

shadertoy-render

What is it: creating video from shaders on Shadertoy. Fork from original, source code edited.

Uploading created video to Twitter/Instagram - pixel format set to yuv420p for libx264 codec and video can be uploaded to any social platform without problems.

Nor supported - Cubemaps, Shader-Cubemap, 3d texture, audio and video input also not supported.

Update 2021:

Added Windows OS support instruction, how to launch it on Windows OS scroll down.

Added correct test for buffers queue example_shadertoy_fbo.

TODO - il develop better "shader recorder" using Vulkan and implementing all missing featres (audio/video/cubemaps/etc). That will be completely new project, this project is done.

Look for useful ffmpeg commands below. (also method of saving single frame(png with alpha) described there)

Changes from original:

  1. added texture support, textures in <0.png to 3.png> bind to iTexture<0-3>
  2. added FrameBuffers, same to Buffer<A-D> on Shadertoy, file name Buf<0-3>.glsl, bind to iChannel<0-3> and u_channel<0-3>
  3. added encoding to *.mov (frames without compression), *.webm (v8 codec), both format support RGBA (video with alpha), added --bitrate option to set video bitrate(format 1M 2M..etc)
  4. fixed iTime(start from 0 on shader launch), iFrame work, iTimeDelta, and other

Warning, when result video does not look the same as on Shadertoy:

Many shaders(even top rated) on Shadertoy may use lots of unitialized variables and clamp(1,0,-1)/pow(-1,-1)/(0/0)/...etc, that work in not same way(have not same result) in OpenGL and webbrowser Angle/GLES, black screen(or other random "results") because of this.

Also remember to set Alpha in main_image.glsl when recording rgba video.

And check for used buffers and textures parameters, this script has clamp_to_edge with linear interpolation for buffers, and repeat with linear without y-flip for textures, Mipmaps not supported.

Example

each shader(buffer) use static bindings iChannel0->Buf0.glsl, iChannel1->Buf1.glsl, iChannel2->Buf2.glsl, iChannel3->Buf3.glsl, also added renamed copy of each channel sampler2D u_channel<0-3>, to rebind inside of .glsl shader(using define)

if you need "change" channel order for shader, use in .glsl file (example set BufA as BufC, and BufC as Texture0(0.png file))

#define iChannel0 u_channel3
#define iChannel3 iTexture0

use same way to bind iTexture<0-3> as iChannel<0-3> #define iChannel0 iTexture0

check examples folders, command to encode example:

cd example_shadertoy_fbo
python3 ../shadertoy-render.py --output 1.mp4 --size=800x450 --rate=30 --duration=5.0 --bitrate=5M main_image.glsl

to record *.mov or *.webm just change output file to .webm or .mov

Example_shadertoy_fbo shadertoy link src webm video recorded with RGBA and test for correct buffers queue video link

Windows OS instruction to launch:

  1. install python3 python 3.9 latest, click Add Python to PATH in setup Window

  2. press Win+R write cmd to launch console

  3. in Windows console write pip install vispy and then pip install watchdog

  4. download glfw3 64-bit Windows binaries and extract from archive

  5. download ffmpeg-git-full (example - Windows builds from gyan - ffmpeg-git-full.7z) and extract

  6. download or clone this shadertoy-to-video-with-FBO

  7. open shadertoy-render.py in text editor

  8. edit line 41 to location of glfw3.dll downloaded and extracted on step 4 notice that \ used as separator (and r in beginning)

  9. edit line 42 to location of ffmpeg.exe downloaded and extracted on step 5 notice that / used as separator

  10. press Win+R write cmd to launch console and launch command, first command path is location of example folder

    > cd C:\shadertoy-to-video-with-FBO-master\example_shadertoy_fbo

    > python ../shadertoy-render.py --output 1.mp4 --size=800x450 --rate=30 --duration=5.0 --bitrate=5M main_image.glsl

Useful ffmpeg commands:

To exptract .png frames with Alpha without compression:

Two options:

  1. if you need just a single frame - add --interactive to this script command line, and press S(keyboard) to save frame.
  2. for many frames - save video as .mov (change file format in comand line) and then:
ffmpeg -i video.mov -vf fps=1 "frames/out%d.png"

To convert Video to Gif ffmpeg commands:

best quality (Linux only) delay = 100/fps

ffmpeg -i video.mp4 -vf "fps=25,scale=480:-1:flags=lanczos" -c:v pam -f image2pipe - | convert -delay 4 - -loop 0 -layers optimize output.gif

not best quality (work on Windows and Linux)

ffmpeg -i video.mp4 -vf "fps=25,scale=640:-1:flags=lanczos" output.gif

About

Render a ShaderToy script directly to a video file. (added FrameBuffers support)

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