vspeed
( Game Maker 6.1, 7 )
vspeed - vertical speed of an instance.
Description
vspeed is a local variable that contains the current vertical speed of a an instance, in pixels per step. A negative vspeed will cause the instance to move up and a positive vspeed will cause the instance to move down.
Examples
Example of Use
vspeed = 1;
In this example, the instance will move 1 pixels down every step.
Limiting vspeed
if(vspeed > 20)
{
vspeed = 20;
}
if (vspeed < -20)
{
vspeed = -20;
}
If this is placed in a Step event, it will limit an object's vspeed to 20. See threshold.
Jumping
From a game design perspective, jumping in a platform game is nothing more than setting the vspeed to a negative number so that the player object starts to move upwards. Eventually, gravity overcomes the initial vspeed, and the object starts to fall down.
gravity = 0.2;
if(keyboard_check(vk_space)){
vspeed = 5;
}
Detecting Up/Down Movement
if(vspeed = abs(vspeed))
{
//instance is moving down
}
else
{
//instance is moving up
}
The code in this example will tell you if an instance is moving up or down during runtime.
Reversing vspeed
You can reverse the vspeed by multiplying it by -1. Note that 1 is the identity element of multiplication.
vspeed = vspeed * -1;
Useful Info
- direction, if it is not set manually, is calculated by using the vspeed and hspeed of an object. If the hspeed and vspeed of an object is , then direction will be "calculated" to . This causes a few problems as is right, not "no direction".
- Changing an object's x/y-position is considered "teleporting" by Game Maker and will not influence or change vspeed.
Related Pages
Variables
- direction - the direction an object is moving, in degrees.
- speed - an objects speed in relation to direction.
- hspeed - the horizontal equivalent of vspeed
