Help with led cube on Rpi

[mph070770]

Hi. I'm new to the world of shaders etc and I'm trying to get shady working on my Rpi 4. I have installed Go on the pi:

pi@raspberrypi:~/rpi-rgb-led-matrix/examples-api-use $ go version
go version go1.16.6 linux/arm

and I'm now trying to work out how to use shady. I've tried this:

../../go/bin/shady -i example2.glsl -ofmt rgb24 -f 20

which complains as follows:

Could initialize engine: failed to call eglCreateContext

I'm not sure if I need OpenGL, and/or what to try next? Sorry, can you help?

[billtraill]

Hi,

Looking at my notes. I got that error when I didn't have

MESA_GL_VERSION_OVERRIDE=3.3

set in the env. My command I use is

MESA_GL_VERSION_OVERRIDE=3.3 EGL_PLATFORM=surfaceless shady -i example.glsl -g 64x64 -f 60 -n $((20*60)) -ofmt rgb24 -o ./my-animation.bin

Bill

On Tue, 27 Jul 2021 at 23:08, mph070770 @.***> wrote:

Hi. I'm new to the world of shaders etc and I'm trying to get shady working on my Rpi 4. I have installed Go on the pi:

@.***:~/rpi-rgb-led-matrix/examples-api-use $ go version go version go1.16.6 linux/arm

and I'm now trying to work out how to use shady. I've tried this:

../../go/bin/shady -i example2.glsl -ofmt rgb24 -f 20

which complains as follows:

Could initialize engine: failed to call eglCreateContext

I'm not sure if I need OpenGL, and/or what to try next? Sorry, can you help?

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[mph070770]

Thanks @billtraill that solved the issue. I've made some good progress. I have used this shader:

https://www.shadertoy.com/view/4sjXRG

with the following command:

../../go/bin/shady -i example3.glsl -g 128x128 -f 20 -ofmt rgb24 | sudo ./ledcat --led-rows=64 --led-cols=64 --led-slowdown-gpio=4 --led-show-refresh --led-chain=2 --led-parallel=3 --led-pwm-bits=11 --led-pwm-lsb-nanoseconds=100 --led-brightness=80 --led-rgb-sequence RBG

having first set this:

export MESA_GL_VERSION_OVERRIDE=3.3

and I get this:

Very pleased :-). The only thing I need to look at now is a bit of flicker. Thanks again @billtraill.

[alienryes]

My hardware is the same one as built here: https://learn.adafruit.com/rgb-led-matrix-cube-for-pi/overview. So it is a chain of 6 panels. I've tried using the command:

../../go/bin/shady -i src-3d.glsl -g 64x64 -f 20 -ofmt rgb24 | ./ledcat --led-rows=64 --led-cols=64 --led-slowdown-gpio=4 --led-chain=6 and using:

MESA_GL_VERSION_OVERRIDE=3.3 EGL_PLATFORM=surfaceless

set in the env.

My results are not so happy:

Any advice welcome