OpenTTD-patches/docs/newgrf-additions-nml.html
2022-01-24 02:30:29 +00:00

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<h2>Additions to NewGRF Specifications in JGR's Patchpack in NML</h2>
<p>This document describes non-standard additions to the <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Main">Official OpenTTD NML Specifications</a> which are present in this patchpack and the associated <a href="https://github.com/JGRennison/nml">NML fork</a>.
<p>These additions MAY also be present in other patchpacks. They MAY be removed or moved in future, if necessary.</p>
<p>Not all standard NewGRF features are supported by NML, consequently not all non-standard additions to the specifications are supported by this patchpack's associated NML fork, or are listed in this document.<br />
See the associated <a href="newgrf-additions.html">non-NML document</a> for more details.</p>
<p>All of the non-standard features listed below will automatically emit suitable feature tests, conditionals, etc. such that NewGRFs which use these features will work correctly
on OpenTTD versions which do not support these features, including standard trunk OpenTTD and older/other patchpack versions.</p>
<p>All of the non-standard variables listed below will return 0 on OpenTTD versions which do not support these features/variables, including standard trunk OpenTTD and older/other patchpack versions.</p>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Builtin_functions">Builtin functions</a></h3>
<p>
<h4>extended_feature_test(feature_name[, min_version[, max_version]])</h4>
This returns true if the given extended feature is present and has a version within the specified minimum and maximum (inclusive).<br />
This function should only be used after the grf{} block.<br />
In most cases it is not necessary to use this function, as extended properties (listed below) which are not supported are simply skipped/ignored.
</p>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#Railtype_properties">Railtypes properties</a></h3>
<table>
<tr><th>Property</th><th>Value range</th><th>Comment</th></tr>
<tr><td>enable_programmable_pre_signals</td><td>0 or 1</td>
<td>
Enable programmable pre-signal graphics in <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a>.<br />
Programmable pre-signals have a signal type (<span class="code">getbits(extra_callback_info2, 16, 8)</span>) of 6.
</td>
</tr>
<tr><td>enable_no_entry_signals</td><td>0 or 1</td>
<td>
Enable no-entry signal graphics in <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a>.<br />
No-entry signals have a signal type (<span class="code">getbits(extra_callback_info2, 16, 8)</span>) of 7.<br />
No-entry signals always have a signal state of red.
</td>
</tr>
<tr><td>enable_restricted_signals</td><td>0 or 1</td>
<td>
Enable restricted signal flag in <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a>.<br />
When enabled, bit 24 of variable <span class="code">extra_callback_info2</span> is set if the signal is restricted (has a routing restriction program attached).<br />
When enabled, the "Show restricted electric signals using default graphics" client setting and signal post recolouring is not applied.<br />
This flag must only be set if a different sprite is returned when bit 24 of <span class="code">extra_callback_info2</span> is set.
</td>
</tr>
<tr><td>enable_signal_recolour</td><td>0 or 1</td>
<td>
Enable recolouring of graphics in <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a>.<br />
When enabled, in addition to returning a sprite, register 0x100 may be set to the following using STORE_TEMP:
<table>
<tr><th>Bits</th><th>Meaning</th></tr>
<tr><td>0 - 23</td><td>Recolour sprite to use. Set to 0 for no recolouring.</td></tr>
<tr><td>24 - 31</td><td>Reserved, set to zero.</td></tr>
</table>
<br />
If recolouring is not optional, the feature name: <span class="code">action0_railtype_recolour</span> should be checked using the
<span class="code">extended_feature_test</span> function
and if necessary a suitable fallback used or error message shown.<br />
If the OpenTTD version does not support this property/feature, then the property would ordinarily be ignored/skipped and no recolouring would be done.
</td>
</tr>
<tr><td>extra_aspects</td><td>0 - 6</td>
<td>
The value is the number of additional signal aspects to use (e.g. 4-aspect signalling should use a value of 2).<br />
When set, the lowest byte of <span class="code">extra_callback_info2</span> (signal state) may have the given number of additional values starting from 02:
<table>
<tr><th>Value</th><th>Meaning</th></tr>
<tr><td>00</td><td>Red signal</td></tr>
<tr><td>01</td><td>Green signal</td></tr>
<tr><td>02</td><td>1st extra aspect (e.g. yellow)</td></tr>
<tr><td>03</td><td>2nd extra aspect (e.g. double yellow)</td></tr>
<tr><td>...</td><td>Further extra aspects...</td></tr>
</table>
<br />
The provided value is currently clamped to be within the range 0 - 6 (inclusive).<br />
N.B. Realistic braking must be enabled for additional signal aspects to be used
</td>
</tr>
<tr><td>disable_realistic_braking</td><td>0 or 1</td>
<td>
When this property is set realistic braking is disabled for trains of this railtype even when realistic braking is otherwise in effect.
</td>
</tr>
</table>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Roadtypes#Roadtype_properties">Roadtype properties</a></h3>
<table>
<tr><th>Property</th><th>Value range</th><th>Comment</th></tr>
<tr><td>roadtype_extra_flags</td><td>bitmask(ROADTYPE_EXTRA_FLAG_XXX, ...)</td>
<td>
<dl>
<dt>NO_SCRIPT_BUILD</dt>
<dd>Scripts (AI/GS) may not build this roadtype</dd>
<dt>NO_TOWN_MODIFY</dt>
<dd>Towns may not modify tiles of this roadtype in any way whatsoever</dd>
</dl>
</td>
</tr>
</table>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Tramtypes#Tramtype_properties">Tramtype properties</a></h3>
<table>
<tr><th>Property</th><th>Value range</th><th>Comment</th></tr>
<tr><td>tramtype_extra_flags</td><td>bitmask(TRAMTYPE_EXTRA_FLAG_XXX, ...)</td>
<td>
<dl>
<dt>NO_SCRIPT_BUILD</dt>
<dd>Scripts (AI/GS) may not build this tramtype</dd>
<dt>NO_TOWN_MODIFY</dt>
<dd>Towns may not modify tiles of this tramtype in any way whatsoever</dd>
</dl>
</td>
</tr>
</table>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Objects#Object_properties">Object properties</a></h3>
<table>
<tr><th>Property</th><th>Value range</th><th>Comment</th></tr>
<tr><td>use_land_ground</td><td>0 or 1</td><td>
Sets whether to use the underlying ground as the object ground sprite, ignoring the ground sprite provided in the sprite layout.<br />
When enabled, the ground sprite will be bare ground, grass, snow, desert, etc. as if it were a clear ground tile.<br />
In edge foundation mode, the ground may be coast/shore when flooded.
</td></tr>
<tr><td>edge_foundation_mode</td><td>[mode0, mode1, mode2, mode3]</td><td>
Enables edge foundation mode for the object.<br />
This property is intended for objects which are positioned at the edge of a tile, and only require a level edge, not a completely level tile.<br />
Foundations will only be added as required to get a suitable level edge.<br />
The format is one mode value per view. If the object has fewer than 4 views then some of the values provided in the property will not be used, and may be 0.
All four values must be constants.<br />
Each mode value should be one of:
<table>
<tr><th>Value</th><th>Meaning</th></tr>
<tr><td>DIAGDIR_NE</td><td>North-east edge</td></tr>
<tr><td>DIAGDIR_SE</td><td>South-east edge</td></tr>
<tr><td>DIAGDIR_SW</td><td>South-west edge</td></tr>
<tr><td>DIAGDIR_NW</td><td>North-west edge</td></tr>
</table>
combined with 0 or more flags using the | operator:
<table>
<tr><th>Value</th><th>Meaning</th></tr>
<tr><td>OBJECT_EF_FLAG_ADJUST_Z</td><td>Change z-position for the building sprite to the height of the edge</td></tr>
<tr><td>OBJECT_EF_FLAG_FOUNDATION_LOWER</td><td>If the height of the edge is lower than the maximum height of the tile, build a foundation</td></tr>
<tr><td>OBJECT_EF_FLAG_INCLINE_FOUNDATION</td><td>Use inclined instead of a flat foundations where possible. (Slopes with one corner raised where the height of the edge is at the maximum height of the tile).</td></tr>
</table>
</td></tr>
<tr><td>flood_resistant</td><td>0 or 1</td><td>
Sets whether the object is flood resistant.<br />
Flood resistance is always enabled for objects which can be built on water.<br />
This property can be used to enable flood resistance without enabling the object to be built on water.
</td></tr>
</table>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Objects#Object_variables">Object variables</a></h3>
<p>Variables in the table below which are not supported by the version of OpenTTD being used return a value of 0.</p>
<table>
<tr><th>Variable</th><th>Value range</th><th>Comment</th></tr>
<tr><td>foundation_tile_slope</td><td><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:List_of_tile_slopes">SLOPE_XXX</a></td><td>
Slope of the tile after any foundation has been applied.
</td></tr>
<tr><td>foundation_change_tile_slope</td><td><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:List_of_tile_slopes">SLOPE_XXX</a></td><td>
Slope of the tile after any foundation has been applied xor the slope of the underlying tile.<br />
If this variable is non-zero a foundation is present.<br />
This is useful for xoring with the tile_slope variable, because if this variable is unavailable then the result is still the underlying tile slope.
</td></tr>
</table>
<h3><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Replace_new_sprites">Replace new sprites</a></h3>
<table>
<tr><th>Type</th><th>Number of sprites </th><th>Comment</th></tr>
<tr><td>PROGRAMMABLE_PRE_SIGNAL</td><td>32</td>
<td>
<b>Programmable pre-signals</b>
<p>Signal graphics come in groups of 16. These groups contain sprites in the same order as sprites 1275-1290 in trg1[r].grf and <a href="https://newgrf-specs.tt-wiki.net/wiki/Action5#04_Signal_graphics.">Action 5 type 4 (signals)</a>;
red, then green, for each of: SW-facing, NE-facing, NW-facing, SE-facing, E-facing, W-facing, S-facing, N-facing.
<table>
<tr><th>Group</th><th>Contents</th></tr>
<tr><td>0</td><td>Semaphore programmable pre-signals</td></tr>
<tr><td>1</td><td>Lighted programmable pre-signals</td></tr>
</table>
</td>
</tr>
<tr><td>NO_ENTRY_SIGNAL</td><td>16</td>
<td>
<b>No-entry signals</b>
<p>No-entry signal graphics come in groups of 8. These groups contain sprites in the same order as the red sprites of 1275-1290 in trg1[r].grf and <a href="https://newgrf-specs.tt-wiki.net/wiki/Action5#04_Signal_graphics.">Action 5 type 4 (signals)</a>;
red only, for each of: SW-facing, NE-facing, NW-facing, SE-facing, E-facing, W-facing, S-facing, N-facing.
<table>
<tr><th>Group</th><th>Contents</th></tr>
<tr><td>0</td><td>Semaphore no-entry signals</td></tr>
<tr><td>1</td><td>Lighted no-entry signals</td></tr>
</table>
</td>
</tr>
<tr><td>MISC_GUI</td><td>1</td>
<td>
<b>Miscellaneous GUI graphics</b>
<p>There is currently one misc GUI sprite.</p>
</td>
</tr>
</table>
<h3>Signal graphics using switches</h3>
<p>
This feature allows signal sprites to be specified using switches in a very similar manner to <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a> in
<span class="code">item (FEAT_RAILTYPES) { graphics { signals: ... } }</span> blocks.<br />
However this applies to all signals, not only those of a particular rail type.<br />
Railtype signal graphics have a higher priority than general signal graphics as set here.<br />
<br />
Variables: <span class="code">extra_callback_info1</span>, <span class="code">extra_callback_info2</span>, and <span class="code">terrain_type</span>
are the same as for <a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Railtypes#signals">railtype signals</a>.<br />
<br />
This feature is not supported by standard OpenTTD or by standard NML.<br/>
If the use of this feature is not optional, the feature name: <span class="code">action3_signals_custom_signal_sprites</span> should be checked using the
<span class="code">extended_feature_test</span> function
and if necessary a suitable fallback used or error message shown.<br />
<br />
An <span class="code">item (FEAT_SIGNALS, custom_signals, 0) { }</span> block should be used to define properties and graphics.<br />
The graphics block should contain a single default switch.
</p>
<table>
<tr><th>Property</th><th>Value range</th><th>Comment</th></tr>
<tr><td>enable_programmable_pre_signals</td><td>0 or 1</td>
<td>
Enable programmable pre-signal graphics.<br />
Programmable pre-signals have a signal type (<span class="code">getbits(extra_callback_info2, 16, 8)</span>) of 6.
</td>
</tr>
<tr><td>enable_no_entry_signals</td><td>0 or 1</td>
<td>
Enable no-entry signal graphics.<br />
No-entry signals have a signal type (<span class="code">getbits(extra_callback_info2, 16, 8)</span>) of 7.<br />
No-entry signals always have a signal state of red.
</td>
</tr>
<tr><td>enable_restricted_signals</td><td>0 or 1</td>
<td>
Enable restricted signal flag.<br />
When enabled, bit 24 of variable <span class="code">extra_callback_info2</span> is set if the signal is restricted (has a routing restriction program attached).<br />
When enabled, the "Show restricted electric signals using default graphics" client setting and signal post recolouring is not applied.<br />
This flag must only be set if a different sprite is returned when bit 24 of <span class="code">extra_callback_info2</span> is set.
</td>
</tr>
<tr><td>enable_signal_recolour</td><td>0 or 1</td>
<td>
Enable recolouring of graphics<br />
When enabled, in addition to returning a sprite, register 0x100 may be set to the following using STORE_TEMP:
<table>
<tr><th>Bits</th><th>Meaning</th></tr>
<tr><td>0 - 23</td><td>Recolour sprite to use. Set to 0 for no recolouring.</td></tr>
<tr><td>24 - 31</td><td>Reserved, set to zero.</td></tr>
</table>
</td>
</tr>
<tr><td>extra_aspects</td><td>0 - 6</td>
<td>
The value is the number of additional signal aspects to use (e.g. 4-aspect signalling should use a value of 2).<br />
When set, the lowest byte of <span class="code">extra_callback_info2</span> (signal state) may have the given number of additional values starting from 02:
<table>
<tr><th>Value</th><th>Meaning</th></tr>
<tr><td>00</td><td>Red signal</td></tr>
<tr><td>01</td><td>Green signal</td></tr>
<tr><td>02</td><td>1st extra aspect (e.g. yellow)</td></tr>
<tr><td>03</td><td>2nd extra aspect (e.g. double yellow)</td></tr>
<tr><td>...</td><td>Further extra aspects...</td></tr>
</table>
<br />
The provided value is currently clamped to be within the range 0 - 6 (inclusive).<br />
N.B. Realistic braking must be enabled for additional signal aspects to be used
</td>
</tr>
</table>
<p>
Custom signal sprites example:
<pre class="code">
grf {
...
}
if (!extended_feature_test("action3_signals_custom_signal_sprites")) {
error(FATAL, string(STR_UNSUPPORTED_VERSION));
}
switch (FEAT_SIGNALS, SELF, switch_signals, ...) {
...
}
item (FEAT_SIGNALS, custom_signals, 0) {
property {
enable_signal_recolour: 1;
}
graphics {
switch_signals;
}
}
</pre>
</p>
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