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(svn r14436) -Fix [FS#1793]: (fast) trains would sometimes move one time too often/little when moving from diagonal<->non-diagonal tracks (iguannab)

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rubidium 2008-10-03 12:55:39 +00:00
parent b727f93bbc
commit da2b14e6b2
1 changed files with 35 additions and 11 deletions
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46
src/train_cmd.cpp
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@ -3227,6 +3227,16 @@ void Train::MarkDirty()
UpdateTrainAcceleration(this);
}
/**
* This function looks at the vehicle and updates it's 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".
* @param v The vehicle to update the speed of.
* @return distance to drive.
*/
static int UpdateTrainSpeed(Vehicle *v)
{
uint accel;
@ -3254,11 +3264,22 @@ static int UpdateTrainSpeed(Vehicle *v)
v->cur_speed = spd = Clamp(v->cur_speed + ((int)spd >> 8), 0, tempmax);
}
if (!(v->direction & 1)) spd = spd * 3 >> 2;
/* 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 v->progress.
*/
int scaled_spd = spd * 3 >> 2;
spd += v->progress;
v->progress = (byte)spd;
return (spd >> 8);
scaled_spd += v->progress;
v->progress = 0; // set later in TrainLocoHandler or TrainController
return scaled_spd;
}
static void TrainEnterStation(Vehicle *v, StationID station)
@ -4279,21 +4300,24 @@ static void TrainLocoHandler(Vehicle *v, bool mode)
InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, VVW_WIDGET_START_STOP_VEH);
}
if (j == 0) {
int adv_spd = (v->direction & 1) ? 192 : 256;
if (j < adv_spd) {
/* if the vehicle has speed 0, update the last_speed field. */
if (v->cur_speed != 0) return;
if (v->cur_speed == 0) SetLastSpeed(v, v->cur_speed);
} else {
TrainCheckIfLineEnds(v);
/* Loop until the train has finished moving. */
do {
j -= adv_spd;
TrainController(v, NULL, true);
CheckTrainCollision(v);
if (v->cur_speed <= 0x100)
break;
} while (--j != 0);
/* 192 spd used for going straight, 256 for going diagonally. */
adv_spd = (v->direction & 1) ? 192 : 256;
} while (j >= adv_spd);
SetLastSpeed(v, v->cur_speed);
}
SetLastSpeed(v, v->cur_speed);
if (v->progress == 0) v->progress = j; // Save unused spd for next time, if TrainController didn't set progress
}