Determines the material type at the specified position in the landscape. Returns a material index which can be used for comparison e.g. with
Material. For sky areas the function returns -1.
This functions only processes static materials - moving material pixels such as rain or snow are not evaluated.
if(GetMaterial(0, +200) == Material("Oil")) Message("Ich bin reich!", this());
Part of a clonk script: if 200 pixels below the calling object oil is found a message is displayed.