#!/bin/bash

if [[ -n "$4" ]]; then
    shaderfile="shaders/${4}.frag"
    if [[ ! -f "$shaderfile" ]]; then
        echo "Error: shader file '$shaderfile' does not exist." >&2
        exit 1
    fi
else
    shaderfile="$(shuf -n1 -e shaders/*)"
fi

export EGL_PLATFORM=surfaceless
export MESA_GL_VERSION_OVERRIDE=3.3

shady -i "${shaderfile}" -ofmt rgb24 -g "${1}x${2}" -f "${3:-20}" -rt

exit 0