NML:Changes 0.3
Introduction
Between NML 0.2.x and NML 0.3.x (and their corresponding nightlies) the generated NewGRF version by NML changed from v7 to v8. This brings lot of advantages, but requires a few changes to existing NML files. NewGRFs thus will require a minimum OpenTTD version of 1.2.0 (r23166).
Callbacks
NML 0.3 only supports the new style callbacks. Thus all callback_flag properties have been removed as have the callback flag constants *CBF*. For a complete list of affected constants see the related commit
New named constants
A few constants have recently been introduced in both NML 0.2 and 0.3 that make the transition easier. Make sure to use them. For callback "articulated_part" use CB_RESULT_NO_MORE_ARTICULATED_PARTS and/or CB_RESULT_REVERSED_VEHICLE instead of hard-coded 0xFF / 0x80. For callbacks "cargo_subtype_text", "cargo_subtype_display" and "start_stop" use CB_RESULT_NO_TEXT instead of hard-coded 0xFF.
Industry availability
The callback "availability" is no longer available. Use the callback "construction_probability" instead.
Changed variables
snowline_height
The "snowline_height" variable returns the height in tiles instead of pixels (=tiles*8).
nearby_tile_height
The "nearby_tile_height" variable returns the height in tiles instead of pixels (=tiles*8).
date_of_last_service
This variable is no longer limited to the range of 1920 ... 2050. It returns now the year 0-based date.
Base costs
Base costs are treated in NewGRF v8 (NML 0.3.x) differently than in NewGRF v7 (NML 0.2.x and earlier). Base costs do NOT influence eachother anymore. You'll need to set all base costs directly and cannot rely anymore that any are set indirectly. See the base costs table which will be influenced.
New properties
Railtypes: alternative_railtype_list
This property allows to define a list of rail types which this rail type will also define - unless the rail type is defined separately.
Trains / Road vehicles: Length
Trains and road vehicles now have a property 'length', this replaces the old property 'shorten_vehicle'.
Cargos: Capacity multiplier
This new property allows answering the question: How much units of cargo X are equivalent to 1 ton of coal, resp. 1000 litres of water?
Houses: watched_cargo_types
With the implementation of this property, the watched_cargo_accepted callback becomes usable.
Vehicle refitting
The 'xor'-property 'refittable_cargo_types' is no longer available, use 'cargo_allow_refit' resp. 'cargo_disallow_refit' instead. For trains, road vehicles and ships you can now specify a default cargo type.
