std::lerp in C++

In this article, we will discuss std:::lerp() method in C++, with its working and implementation.

What is the std::lerp?

The std::lerp (introduced in C++20) is a versatile function for performing linear interpolation (LERP) between two values. It calculates a new value based on a weighting factor (t) between a starting point (a) and an ending point (b).

How does it work?

The core formula for std::lerp is:

result = a + t * (b - a)

• result: The interpolated value
• a: The starting value
• t: The weighting factor (interpolation parameter)
• b: The ending value

The t value controls the influence of each endpoint on the result:

• t = 0: It returns a (no interpolation).
• 0 < t < 1: Interpolate between a and b based on t
• t = 1: It returns b (no interpolation)
• t < 0 or t > 1: Extrapolation occurs (values outside the range of a and b)
• a, b: The values between which to interpolate.
• t: The interpolation parameter, a value between 0 and 1. When t is 0, the function returns a, and when t is 1, it returns b.

Example:

Let us take an example to illustrate the Std::lerp in C++.

#include 

// Linear interpolation function

float lerp(float a, float b, float t) {

    return a + t * (b - a);

}

int main() {

    float start = 2.0f;

    float end = 8.0f;

    float factor = 0.5f;  // Midway between start and end

    float interpolated = lerp(start, end, factor);

    std::cout << "Interpolated value: " << interpolated << std::endl;  // Output: 5.0

    return 0;

}

Output:

Interpolated value: 5

Behavior for Different t Values:

Applications:

• Animation: Smoothly transition between animation frames.
• Game development: Create dynamic movements, interpolate colors, etc.
• User interfaces: Implement smooth transitions between UI elements.
• Scientific computing: Linearly interpolates data points for visualization or analysis.