[ACS] Real Elevators - Accelerating and Decelerating Lifts

[Nero]

One of the quality of life things I've always wanted: elevators that would move like the real thing; in other words, they accelerate when they start to move and decelerate when they near their destination.
Ok...that's not that tall an order is it? ... ... ... ... Yes and no.

Anyway, introducing Real Elevators(v0.3), a tiny code library that does just what I've always wanted in a nice neat package!

So, how it works: there's more under the hood than this, but the only function - yes function - users need to know about is MoveElevator. This function is called from a script that should be activated by the player, as shown below.

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/*
    This function is called from implementation scripts to move an elevator.
    It is assumed that it is a player that is the script activator.
    
    Args:
    ElevatorId, int, this is the sector id of the elevator control sector(s).
    SkipAccel, bool, if true the elevator will begin moving at full speed but can still decelerate.
    SkipDecel, bool, if true the elevator will move to its final position at full speed.
    TotalDist, int, how far the elevator will move; positive values move up, negative move down.
    MaxSpeed, int, the maximum speed the elevator will move at.
    AccelDist, int, how much of the Total Distance will be used for accelerating AND decelerating; this value is effectively doubled.
    MoveStartBias, int, this value increases or decreases the rate of acceleration for the first half of acceleration; positive increase, negative decrease.
    MoveEndBias, int, this value increases or decreases the rate of deceleration for the last half of deceleration; positive increase, negative decrease.
    JustFloor, bool, if true only the floor of the given sector will be moved; this is for regular lifts and not 3D floor elevators!
*/
function void MoveElevator (int ElevatorId, bool SkipAccel, bool SkipDecel, int TotalDist, int MaxSpeed, int AccelDist, int MoveStartBias, int MoveEndBias, bool JustFloor)
{
    // . . . stuff that none of us ever have to do again to make an elevator accelerate or decelerate :P
}

A script using MoveElevator might look like this: the script is called from another which is flagged as an ENTER script, thus the player is the activator of this elevator script, which also handles level transition effects.

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//Starting Location/Level Selection Elevator
script "LEVELELEVATORSTART" (void)
{
    SetPlayerProperty(0, 1, PROP_TOTALLYFROZEN);
    FadeTo(24, 24, 24, 1.0, 0.0);
    Thing_Move(0, 1043, 1);
    MoveElevator(3000, true, false, -212, 15, 96, 0, 1, false);
        delay(15);
    SetPlayerProperty(0, 0, PROP_TOTALLYFROZEN);
    FadeTo(24, 24, 24, 0.0, 0.5);
}

Features:

• This library should be multiplayer friendly, allowing up to 8 players to be activating and riding elevators at any given time.
• I originally designed this around elevators made from 3D floors, but I've also tweaked the code to include regular lifts as well.

Download:
Most Recent Version:

• RealElevators_0-3.pk3

Old Versions:

• RealElevators_0-2.pk3

Usage:

• Load the package you downloaded with ZDL or equivalent.
• Mod authors are free to do with this as they please, especially integrate into their own stuff, I just ask for credit, thanks!

Updates:

• Pretty sure this is done and I won't be updating it any time soon. I'm already using this code in my own stuff and I added multiplayer and regular lifts for the public release, so it seems pretty feature complete to me. Please let me know if you have any problems or suggestions!
• v0.3! - well I thought I was done but then I had another thought: what if someone wants the elevator to not decelerate? Like what if you want to "break" an elevator mid-transit? It doesn't make sense that it should necessarily come to a nice gradual halt. So deceleration skipping is now a feature. This does mean that the MoveElevator function has received an additional argument.

---

Code: Select all • Expand view

/*
    This code allows an elevator to acclerate at the 
    beginning of its movement, and decelerate at the end.
    
    Written by Sarah Blackburn (Nero)
    
    This code is provided as-is with no guarantees of any kind.
    You use this code in your own projects at your own risk.
    
    Please contact the author with any questions on the ZDoom Forum.
    
    You are free to do with this code as you see fit,
    but I do request credit in your project if you use my code.
    
    Thanks!

*/

#LIBRARY "ELEACCEL"
#include "zcommon.acs"

/*
    This defines how far the elvator moves each loop.

*/
#define ELE_MOVEINCREMENT 8

/*
    This system is multiplayer friendly! Up to 8 players are supported;
    and could be expanded through simple tweaks (like if it was used for Zandronum).
    The array below stores the relevant data that can't be passed by script:
        - does the elevator need to skip accelerating?
        - what about skipping deceleration?
        - what is the control sector id?
        - does it have an acceleration bias?
        - what about a deceleration bias?
        - what kind of elevator is it?

*/
int map_arPlayerElevatorData[8][6];

#define ELE_SKIP_ACCEL        0
#define ELE_SKIP_DECEL        1
#define ELE_ID                2
#define ELE_ACCEL_BIAS        3
#define ELE_DECEL_BIAS        4
#define ELE_TYPE            5

/*
    This function is called from implementation scripts to move an elevator.
    It is assumed that it is a player that is the script activator.
    
    Args:
    ElevatorId, int, this is the sector id of the elevator control sector(s).
    SkipAccel, bool, if true the elevator will begin moving at full speed but can still decelerate.
    SkipDecel, bool, if true the elevator will move to its final position at full speed.
    TotalDist, int, how far the elevator will move; positive values move up, negative move down.
    MaxSpeed, int, the maximum speed the elevator will move at.
    AccelDist, int, how much of the Total Distance will be used for accelerating AND decelerating; this value is effectively doubled.
    MoveStartBias, int, this value increases or decreases the rate of acceleration for the first half of acceleration; positive increase, negative decrease.
    MoveEndBias, int, this value increases or decreases the rate of deceleration for the last half of deceleration; positive increase, negative decrease.
    JustFloor, bool, if true only the floor of the given sector will be moved; this is for regular lifts and not 3D floor elevators!
*/
function void MoveElevator (int ElevatorId, bool SkipAccel, bool SkipDecel, int TotalDist, int MaxSpeed, int AccelDist, int MoveStartBias, int MoveEndBias, bool JustFloor)
{
    if (PlayerNumber() != -1)
    {
        map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_ACCEL] = SkipAccel;
        map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_DECEL] = SkipDecel;
        map_arPlayerElevatorData[PlayerNumber()][ELE_ID] = ElevatorID;
        map_arPlayerElevatorData[PlayerNumber()][ELE_ACCEL_BIAS] = MoveStartBias;
        map_arPlayerElevatorData[PlayerNumber()][ELE_DECEL_BIAS] = MoveEndBias;
        map_arPlayerElevatorData[PlayerNumber()][ELE_TYPE] = JustFloor;
        ACS_NamedExecute("ElevatorMove", 0, TotalDist, MaxSpeed, AccelDist);
    }
}

/*
    These are wrapper functions used by the "ElevatorMove" script to
    eliminate the unpleasant array access.

*/
function bool GetSkipAccel(void) { return map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_ACCEL]; }
function bool GetSkipDecel(void) {return map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_DECEL]; }
function int GetElevatorId(void) { return map_arPlayerElevatorData[PlayerNumber()][ELE_ID]; }
function int GetStartBias(void) { return map_arPlayerElevatorData[PlayerNumber()][ELE_ACCEL_BIAS]; }
function int GetEndBias(void) { return map_arPlayerElevatorData[PlayerNumber()][ELE_DECEL_BIAS]; }
function bool GetElevatorType(void) { return map_arPlayerElevatorData[PlayerNumber()][ELE_TYPE]; }
function void ClearElevator(void)
{
        map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_ACCEL] = false;
        map_arPlayerElevatorData[PlayerNumber()][ELE_SKIP_DECEL] = false;
        map_arPlayerElevatorData[PlayerNumber()][ELE_ID] = 0;
        map_arPlayerElevatorData[PlayerNumber()][ELE_ACCEL_BIAS] = 0;
        map_arPlayerElevatorData[PlayerNumber()][ELE_DECEL_BIAS] = 0;
        map_arPlayerElevatorData[PlayerNumber()][ELE_TYPE] = false;
}

/*
    This remarkably simple function returns the average
    acceleration over a given distance.  Note that this
    formula supplants time for distance.

    You use this functions as follows:
    fvel - final velocity, this is how fast the object should be moving at the end of the move
    svel - the starting velocity, this is how how fast the object is moving at the start of the move
    d - distance, this is how far the object is going to move.

    You may invert this equation to decelerate as well.

    Oh and this function is fairly simple, but the script that relies on it certainly isn't!

*/
function int AccelerationIs(int fvel, int svel, int d)
{
    return (fvel - svel) / d < 0 ?            // Is the result less than 0?
                ((fvel - svel) / d) * -1 :    // It is, so return it multiplied by -1 to make it positive.
                (fvel - svel) / d;            // It's not, so return it normal.
}

// Set total distance to negative to move down
// TotalDistance is the total move distance of the elevator
// MaxSpeed is the final velocity
// AccelerationDistance is the the number of units reserved for acceleration/deceleration - this value is doubled!
script "ElevatorMove" (int TotalDistance, int MaxSpeed, int AccelerationDistance)
{
    // These just make the names simpler
    int td = TotalDistance;
    int mx = MaxSpeed;
    int ad = AccelerationDistance;

    // Move biases - if non-zero these change the rate of accel/deceleration during the first and last halfs of these operations respectively
    int msb = GetStartBias();
    int meb = GetEndBias();

    // Moving up or down?
    bool moveDir = true;          // Up
    if (td < 0)
    {
        td *= -1;
        moveDir = false;        // Down
    }

    // How far we have to go
    int curDist = td;
    // Current speed
    int curSpeed = AccelerationIs(mx, 0, ELE_MOVEINCREMENT);

    // Moving id 0 would be to move the world!
    if (GetElevatorId() > 0)
    {
        while (curDist > 0)
        {
            // This is how far we move each iteration
            int moveIncr = ELE_MOVEINCREMENT;
            // Now is that going to put the elevator past it's target?
            if (curDist - moveIncr < 0)
                moveIncr = td - (td - curDist);

            // Now we move the elevator.
            // There are three options here:
            // Accelerate
            if (!GetSkipAccel() && curDist >= td - ad)
            {
                curSpeed += AccelerationIs(mx, curSpeed, moveIncr) + (curDist >= td - (ad / 2) ? msb : 0);
                if (curSpeed > mx)
                    curSpeed = mx;
            }
            // decelerate
            else if (!GetSkipDecel() && curDist <= ad)
            {
                curSpeed -= AccelerationIs(0, curSpeed, moveIncr) + (curDist <= ad / 2 ? meb : 0);
                if (curSpeed <= 0)
                    curSpeed = 1;
            }
            // Remain constant
            else
                curSpeed = mx;

            /*Log (s:"Elevator: ", d:GetElevatorId(), s:", is moving ", s:(moveDir ? "up.\n" : "down.\n"),
                s:"Player riding is: ", d:PlayerNumber(), s:"\n",
                s:"Total Distance is: ", d:td, s:"\n",
                s:"Max Speed is: ", d:mx, s:"\n",
                s:"Acceleration Distance is: ", d:ad, s:"\n",
                s:"Current Speed is: ", d:curSpeed, s:"\n",
                s:"Move Increment is: ", d:moveIncr, s:"\n",
                s:"Current Distance is: ", d:curDist, s:"\n\n");*/

            if (moveDir)
            {
                if (GetElevatorType())
                    Floor_RaiseByValue(GetElevatorId(), curSpeed, moveIncr);
                else
                    FloorAndCeiling_RaiseByValue(GetElevatorId(), curSpeed, moveIncr);
            }
            else
            {
                if (GetElevatorType())
                    Floor_LowerByValue(GetElevatorId(), curSpeed, moveIncr);
                else
                    FloorAndCeiling_LowerByValue(GetElevatorId(), curSpeed, moveIncr);
            }

            // Finally subtract the move increment from the current distance, if this ends up 0 the loop ends.
            curDist -= moveIncr;
            // Going to try and wait for the sector to stop moving without putting in a Delay.
            TagWait(GetElevatorId());
        }

        ClearElevator();
    }
}