A3D_PredictTrajectory

Follow something thrown, such as a grenade, and find where it first lands.

The path is the curve of the throw under gravity, without air resistance. With a radius, a sphere of that size is followed and the point is its centre when it touches. Start outside the thrower, or leave A3D_COLLIDE_PLAYERS out of flags.

native bool:A3D_PredictTrajectory(
    Float:x,
    Float:y,
    Float:z,
    Float:vx,
    Float:vy,
    Float:vz,
    &Float:hitX,
    &Float:hitY,
    &Float:hitZ,
    &Float:time = 0.0,
    &A3D_HIT:type = A3D_HIT_MAP,
    &hitid = 0,
    &material = 0,
    Float:radius = 0.0,
    Float:gravity = 9.81,
    Float:duration = 10.0,
    worldid = -1,
    A3D_COLLIDE:flags = A3D_COLLIDE_ALL
);

Parameters

Parameter	Description	Default
Float:x	Start on the X axis.
Float:y	Start on the Y axis.
Float:z	Start on the Z axis.
Float:vx	Speed on the X axis, in metres per second.
Float:vy	Speed on the Y axis.
Float:vz	Speed on the Z axis.
&Float:hitX	Point where it lands on the X axis.
&Float:hitY	Point on the Y axis.
&Float:hitZ	Point on the Z axis.
&Float:time	Seconds it flies.	0.0
&A3D_HIT:type	What it lands on.	A3D_HIT_MAP
&hitid	Model of the map object, or the physics object, static object, player, vehicle or actor.	0
&material	Surface of the game it lands on.	0
Float:radius	Radius of what is thrown, or 0.0 for a point.	0.0
Float:gravity	Gravity in metres per second squared.	9.81
Float:duration	Longest flight followed, in seconds.	10.0
worldid	Virtual world to look in, or -1 for every world.	-1
A3D_COLLIDE:flags	What it may land on.	A3D_COLLIDE_ALL

Returns

• true when it lands within duration.
• false when it flies on, or falls below 3dandreas.floor.

How it works

The flight is cut into steps of 1/30 second. Each step follows the straight line between two points of the curve, as a ray or, with a radius, as a sphere sweep. A step strays from the curve by under two millimetres at the gravity of the game, so the landing point lies on the curve. time is measured along the step that lands.

The throw has no air resistance and no bounce. The first touch is the landing. The search ends at duration, or when the path falls below 3dandreas.floor.

A throw that lands 60 metres away costs about 60 microseconds.

Notes

• Start the throw outside the thrower, or leave A3D_COLLIDE_PLAYERS out of the flags, or it lands on the thrower at once.
• With A3D_COLLIDE_WATER in the flags, the throw lands on the water. Without it, it lands on the bottom.
• The result matches a physics object thrown the same way only until it first touches something, since the object then bounces and rolls.

Example

Marks where a grenade thrown where the camera looks would land.

stock MarkGrenade(playerid) {
    new
        Float:x,
        Float:y,
        Float:z,
        Float:frontX,
        Float:frontY,
        Float:frontZ,
        Float:hitX,
        Float:hitY,
        Float:hitZ,
        Float:time,
        A3D_HIT:type,
        hitid,
        material
    ;

    GetPlayerPos(playerid, x, y, z);
    GetPlayerCameraFrontVector(playerid, frontX, frontY, frontZ);

    if (!A3D_PredictTrajectory(x, y, z + 0.7, frontX * 15.0, frontY * 15.0, frontZ * 15.0 + 4.0, hitX, hitY, hitZ, time, type, hitid, material, 0.1, .worldid = GetPlayerVirtualWorld(playerid), .flags = A3D_COLLIDE_ALL & ~A3D_COLLIDE_PLAYERS)) {
        return;
    }

    SetPlayerCheckpoint(playerid, hitX, hitY, hitZ, 1.0);
}

Related

• A3D_SweepSphere: Move a sphere along a segment and find where it first touches something.
• A3D_RayCast: Find the first thing a segment between two points hits.
• A3D_SetGravity: Set how strongly a moving physics object falls.