Function GetEngineColourMap

src/vehicle.cpp:2074–2115

static PaletteID GetEngineColourMap(EngineID engine_type, CompanyID company, EngineID parent_engine_type, const Vehicle *v)
{
	PaletteID map = (v != nullptr) ? v->colourmap : PAL_NONE;

	/* Return cached value if any */
	if (map != PAL_NONE) return map;

	const Engine *e = Engine::Get(engine_type);

	/* Check if we should use the colour map callback */
	if (e->info.callback_mask.Test(VehicleCallbackMask::ColourRemap)) {
		uint16_t callback = GetVehicleCallback(CBID_VEHICLE_COLOUR_MAPPING, 0, 0, engine_type, v);
		/* Failure means "use the default two-colour" */
		if (callback != CALLBACK_FAILED) {
			static_assert(PAL_NONE == 0); // Returning 0x4000 (resp. 0xC000) coincidences with default value (PAL_NONE)
			map = GB(callback, 0, 14);
			/* If bit 14 is set, then the company colours are applied to the
			 * map else it's returned as-is. */
			if (!HasBit(callback, 14)) {
				/* Update cache */
				if (v != nullptr) const_cast<Vehicle *>(v)->colourmap = map;
				return map;
			}
		}
	}

	bool twocc = e->info.misc_flags.Test(EngineMiscFlag::Uses2CC);

	if (map == PAL_NONE) map = twocc ? (PaletteID)SPR_2CCMAP_BASE : (PaletteID)PALETTE_RECOLOUR_START;

	/* Spectator has news shown too, but has invalid company ID - as well as dedicated server */
	if (!Company::IsValidID(company)) return map;

	const Livery *livery = GetEngineLivery(engine_type, company, parent_engine_type, v, _settings_client.gui.liveries);

	map += livery->colour1;
	if (twocc) map += livery->colour2 * 16;

	/* Update cache */
	if (v != nullptr) const_cast<Vehicle *>(v)->colourmap = map;
	return map;
}

/**
 * Get the colour map for an engine. This used for unbuilt engines in the user interface.