float brightness() {
  return 0.0;
}

//Do not change this line
#pragma glslify: export(brightness)

float brightness() {
  return -1.0;
}

//Do not change this line
#pragma glslify: export(brightness)

Fix shader file in 00-intro-0
Fix shader file in 00-intro-0

Fixes #45. Thanks @justinabrahms!
