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#ifndef simunits_h
#define simunits_h
/*
* Copyright 2010 Nathanael C. Nerode
* & Simutrans Contributors
* This file is part of the Simutrans project and is available under the
* Artistic License -- see license.txt
*/
/*
* This file is designed to contain the unit conversion routines
* which were previously scattered all over the Simutrans code.
*
* Some are still scattered all over the code. So this file also documents
* where the other conversion routines are.
*
* I have tried to leave out stuff which should be internal to the display
* and have no gameplay consequences.
*
* DISTANCE units:
* 1 -- tiles
* 2 -- "internal pixels" -- 16 per tile. Old steps per tile.
-- OBJECT_OFFSET_STEPS, located in simconst.h
-- important to the internal rendering engine
-- used for locating images such as trees within a tile
-- same value as carunits, but conceptually different....
* 3 -- "carunits" or vehicle length units -- same as old steps per tile
-- Length of trains & other vehicles (as specified in paks)
-- is measured in this unit. Currently this is very hard to alter.
* 4 -- vehicle steps
-- trains can be on one of 2^8 = 256 locations along a tile horizontally (not
diagonally).
* 5 -- "yards" -- tiny distance units used internally
-- 2^12 per vehicle steps, by definition
-- 2^16 per vehicle steps in older code
-- chosen to maximize precision of certain interfaces
* 6 -- km -- 1/tile in standard
*
* TIME units:
* 1 -- ticks -- referred to as ms or milliseconds in old code
* 2 -- months -- determined by karte_t::ticks_per_world_month
* -- you may also use karte_t::ticks_per_world_month_shift
* 3 -- days -- derived from months
* 4 -- years -- derived from months
* 5 -- hours & minutes -- NOT derived from months, implied by vehicle speed
* 6 -- actual real-time milliseconds -- only for game speed setting
* -- no meaning in-game
*
* SPEED units:
* 1 -- "internal" speed -- yards per tick.
* -- this is multiplied by delta_t, which is in ticks (in convoi_t::sync_step)
* -- to get distance travelled in yards (passed to vehikel_t:fahre_basis)
* 2 -- km/h -- core setting here is VEHICLE_SPEED_FACTOR
* 3 -- tiles per tick
* 4 -- steps per tick
*
* ELECTRICITY units:
* 1 -- "internal" units
* 2 -- megawatts
* This conversion still lives in dings/leitung2.h, not here
*/
/*
* Distance units: conversion between "vehicle steps" and "yards"
* In bitshift form
*/
#define YARDS_PER_VEHICLE_STEP_SHIFT (12)
/*
* Mask, applied to yards, to eliminate anything smaller than a vehicle step
* Assumes yards are in uint32 variables.... derivative of YARDS_PER_VEHICLE_STEP_SHIFT
* #define YARDS_VEHICLE_STEP_MASK (0xFFFFF000)
*/
#define YARDS_VEHICLE_STEP_MASK ~((1<<YARDS_PER_VEHICLE_STEP_SHIFT)-1)
/*
* Distance units: vehicle steps per tile
* A vehicle travelling across a tile horizontally can be in this many
* distinct locations along the tile
* This is 256, and making it larger would require changing datatypes within
* vehikel_t.
*/
#define VEHICLE_STEPS_PER_TILE (256)
#define VEHICLE_STEPS_PER_TILE_SHIFT 8
/*
* Shift from yards to tiles, derived quantity
*/
#define YARDS_PER_TILE_SHIFT (VEHICLE_STEPS_PER_TILE_SHIFT + YARDS_PER_VEHICLE_STEP_SHIFT)
/*
* Distance units: "carunits" per tile
* Forced by history of pak files to 16
*/
#define CARUNITS_PER_TILE (16)
/*
* Distance units: steps per carunit
* Derived from the above two....
*/
#define VEHICLE_STEPS_PER_CARUNIT (VEHICLE_STEPS_PER_TILE/CARUNITS_PER_TILE)
/*
* "Unlimited" speed depends on size of "speed" unit (sint32)
*/
#define SPEED_UNLIMITED (2147483647) // == SINT32_MAX
/*
* Global vehicle speed conversion factor between Simutrans speed
* and km/h
* @author Hj. Malthaner
*/
#define VEHICLE_SPEED_FACTOR (80)
/**
* Converts speed value to km/h
* @author Hj. Matthaner
* this is speed * VEHICLE_SPEED_FACTOR / 2^10 rounded to nearest
*/
#define speed_to_kmh(speed) (((speed)*VEHICLE_SPEED_FACTOR+511) >> 10)
/**
* Converts km/h value to speed
* @author Hj. Matthaner
* this is speed * 2^10 / VEHICLE_SPEED_FACTOR
*/
#define kmh_to_speed(speed) (((speed) << 10) / VEHICLE_SPEED_FACTOR)
/*
* Converts speed (yards per tick) into tiles per month
*/
// Done in simworld.h: speed_to_tiles_per_month
#endif /* simunits.h */
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