diff options
| -rw-r--r-- | src/train_cmd.cpp | 46 |
1 files changed, 35 insertions, 11 deletions
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp index 7b99dd0c8..69a56ab40 100644 --- a/src/train_cmd.cpp +++ b/src/train_cmd.cpp @@ -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 } |