# GroundVelocity
### Introduction
The GroundVelocity property is used to simulate the ground moving under the player. By default GroundVelocity is a 0-length vector which means the player is not standing on moving ground.
GroundVelocity can be set for the following reasons:
* Simulating standing on moving ground such as a treadmill or moving walkway
* Standing on a moving platform such as log floating on a river
* Being pushed by the environment such as standing in blowing wind or flowing water
{% hint style="warning" %}
GroundVelocity is a Vector3 for convenience when applying velocity, but only the X and Y values should be assigned. Setting the Z value results in the entity's Z value changing which can affect ordering or even move the entity out of the camera's minimum and maximum Z values.
In other words, be sure to keep GroundVelocity.Z set to 0.
{% endhint %}
### Code Example - Setting Ground Velocity
GroundVelocity can be set per instance. For example, the following code sets the GroundVelocity on Player1 when the Space bar is held down.
```csharp
if(Keyboard.Main.KeyDown(Microsoft.Xna.Framework.Input.Keys.Space))
{
Player1.GroundVelocity = new Vector3(32, 0, 0);
EditorVisuals.Text("Space is held", Camera.Main.Position.AtZ(0));
}
else
{
Player1.GroundVelocity = new Vector3(0, 0, 0);
}
```
Player1 moving when space is held.
### GroundVelocity Affects Movement
Top down entity movement is performed relative to GroundVelocity. If GroundVelocity is assigned to a non-zero vector, then all movement is performed relative to that new value. For example, if GroundVelocity is set to have an X value of 32, then the entity can move 32 pixels faster on the X axis when moving to the right, and 32 pixels slower when moving to the left.
Player moving around with a GroundVelocity.X value set to 32
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