in unity/Assets/PostProcessingV2/Editor/Effects/ColorGradingEditor.cs [215:237]
void DoExternalModeGUI()
{
PropertyField(m_ExternalLut);
var lut = m_ExternalLut.value.objectReferenceValue;
if (lut != null)
{
if (lut.GetType() == typeof(Texture3D))
{
var o = (Texture3D)lut;
if (o.width == o.height && o.height == o.depth)
return;
}
else if (lut.GetType() == typeof(RenderTexture))
{
var o = (RenderTexture)lut;
if (o.width == o.height && o.height == o.volumeDepth)
return;
}
EditorGUILayout.HelpBox("Custom LUTs have to be log-encoded 3D textures or 3D render textures with cube format.", MessageType.Warning);
}
}