Question: What is lerp in GameMaker?

Answer

lerp, standing for linear interpolation, is a function in GameMaker that smoothly transitions between two values. It's commonly used in animations, movements, scaling, and various other instances where a value needs to change at a certain rate over time.

The lerp function takes three arguments: the start value, the end value, and the interpolation factor (usually a value between 0 and 1). The interpolation factor determines how close the returned value is to the start or end value. An interpolation factor of 0 will return the start value, an interpolation factor of 1 will return the end value, and an interpolation factor of 0.5 will return exactly halfway between the two.

Here's the basic syntax for lerp:

var result = lerp(start_value, end_value, interpolation_amount);

For example, if you want to move an object from its current position to a new position smoothly over time, you could use lerp like this:

// Create event:
target_x = 100; // Target x position
move_speed = 0.05; // How quickly the object moves to the target

// Step event:
x = lerp(x, target_x, move_speed);

In the code above, move_speed dictates how quickly the object will move towards target_x. Each step, the object's x coordinate will get closer to target_x by 5%.

Note that lerp can sometimes never reach the end value due to the nature of floating-point precision and the fact that it's a percentage-based approach. When using lerp for such purposes, it might be necessary to set a threshold below which you would just set the value to the end value directly to avoid an endless approach.