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(svn r20079) -Codechange [FS#3922]: Add helper functions to deal with the 192-256-magic of vehicle movement.

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frosch
2010-07-04 13:07:47 +00:00
parent ed2213df23
commit a7d168b2e5
5 changed files with 68 additions and 27 deletions
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25
src/train_cmd.cpp
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@@ -2839,10 +2839,8 @@ void Train::MarkDirty()
/**
* This function looks at the vehicle and updates its speed (cur_speed
* and subspeed) variables. Furthermore, it returns the distance that
* the train can drive this tick. This distance is expressed as 256 * n,
* where n is the number of straight (long) tracks the train can
* traverse. This means that moving along a straight track costs 256
* "speed" and a diagonal track costs 192 "speed".
* the train can drive this tick. #Vehicle::GetAdvanceDistance() determines
* the distance to drive before moving a step on the map.
* @return distance to drive.
*/
int Train::UpdateSpeed()
@@ -2869,18 +2867,7 @@ int Train::UpdateSpeed()
this->cur_speed = spd = Clamp(this->cur_speed + ((int)spd >> 8), 0, tempmax);
}
/* Scale speed by 3/4. Previously this was only done when the train was
* facing diagonally and would apply to however many moves the train made
* regardless the of direction actually moved in. Now it is always scaled,
* 256 spd is used to go straight and 192 is used to go diagonally
* (3/4 of 256). This results in the same effect, but without the error the
* previous method caused.
*
* The scaling is done in this direction and not by multiplying the amount
* to be subtracted by 4/3 so that the leftover speed can be saved in a
* byte in this->progress.
*/
int scaled_spd = spd * 3 >> 2;
int scaled_spd = this->GetAdvanceSpeed(spd);
scaled_spd += this->progress;
this->progress = 0; // set later in TrainLocoHandler or TrainController
@@ -3885,7 +3872,7 @@ static bool TrainLocoHandler(Train *v, bool mode)
SetWindowDirty(WC_VEHICLE_VIEW, v->index);
}
int adv_spd = (v->direction & 1) ? 192 : 256;
int adv_spd = v->GetAdvanceDistance();
if (j < adv_spd) {
/* if the vehicle has speed 0, update the last_speed field. */
if (v->cur_speed == 0) SetLastSpeed(v, v->cur_speed);
@@ -3897,8 +3884,8 @@ static bool TrainLocoHandler(Train *v, bool mode)
TrainController(v, NULL);
/* Don't continue to move if the train crashed. */
if (CheckTrainCollision(v)) break;
/* 192 spd used for going straight, 256 for going diagonally. */
adv_spd = (v->direction & 1) ? 192 : 256;
/* Determine distance to next map position */
adv_spd = v->GetAdvanceDistance();
/* No more moving this tick */
if (j < adv_spd || v->cur_speed == 0) break;