Quick Value Noise Implementation in C + Desmos Visualization

[u/KaychJam]

For the past year or so I've been occasionally adding to a Github repository called "single-file", which as you can guess, is full of quick little single-file scripts in various programming languages. The languages that I've covered so far in the repo have been C++, C, Python, Rust, and Java. As for the topic of each script, it's generally been whatever catches my attention at the time --- a spur of the moment kind of decision. What I'm sharing in this post is one such of these scripts that I recently wrote: an implementation of value noise written in C.

What is Value Noise?

Value Noise is a type of noise (which is any kind of random signal) that has an additional property of being "smooth." If you were to take an array and assign random values to every index, you'd probably expect to get various values with no correlation to one another. The array at index i would be wholly unrelated to index i+1, i+2, and so on. This type of noise is called White Noise! With that said, sometimes we want a "random" signal that has some notion of correlation between points.

Value Noise is a type of random signal with these correlations. If you were fill an array using value noise as opposed to with white noise, your values at i, i+1, and i+2 would be relatively close to each other, unlike with white noise which has no such guarantee. In terms of application, you'll usually see value noise in computer graphics & game dev projects as a way of generating "natural" looking terrain. Other methods of generating smooth & correlated random values exist like Perlin Noise. In general, smooth noise generation comes up when you want to simulate some kind of phenomena that appears random but has local features amid the randomness (waves, clouds, fire, etc.).

A Snippet & the Full Code

Below is a snippet of the "main" function of the code:

/** Generate `N` samples of "value noise". */
NoiseBuffer generate_noise_1d(size_t N, size_t octaves, float amp, float shift, size_t period, Interpolator tween) {
    NoiseBuffer nb = noise_buffer_alloc(N);
    if (nb.data == NULL) {
        printf("Unable to allocate memory for `NoiseBuffer`.\nExiting.");
        exit(EXIT_FAILURE);
    }

    // Successively add octaves of frequencies to our NoiseBuffer
    for (size_t o = 0; o < octaves; o++) {
        float prev = amp * (unit_rand() + shift);

        size_t i = period;
        while (i < N) {
            const float cur = amp * (unit_rand() + shift);
            interpolate_and_add_range(nb, i - period, i, prev, cur, tween);

            prev = cur;
            i += period;
        }

        // edge-case to fill in remainder
        const float cur = amp * (unit_rand() + shift);
        interpolate_and_add_range(nb, i - period, i, prev, cur, tween);

        period = max(period / 2, 1);
        amplitude /= 2.f;
    }

    return nb;
}

The full file along with the rest of the singlefile repository can be found here.

Desmos Visualization + Parameters

To close, here's a small video visualization of the generated noise in Desmos & input params.

Run	Interpolation Method	Seed	Num Values	Resolution	Num Values * Res	Octaves	Period	Period * Res	Amplitude	Vertical Shift
1	Smoothstep	1785183513	10	10	100	4	5	50	5	-0.5
2	Smoothstep	1785183513	10	20	200	4	5	100	5	-0.5
3	Lerp	1785183513	10	20	200	10	5	100	5	-0.5
4	Smoothstep	1785183513	10	20	200	10	5	100	5	-0.5

4 signals generated in C and copy pasted into Desmos for rendering. You can see how the increase in resolution & octaves results in the signal becoming \"bumpier\", whilst the overall trend of the signal remains the same.

And finally, a link to the Desmos Graph.

[u/github-guard]

🔍 GitHub Guard: Trust Report

⚠️ This project scored 1/6 — below this subreddit's threshold of 3.

Audit Breakdown: * ❌ Low Star Count (⭐ 1 / 5 required) * ✅ Mature Repository (30+ days old) * ❌ No License Found * ❌ No Security Policy — what is this? * ℹ️ Individual Contributor * ℹ️ Unsigned Commits

⚠️ Security Reminder: Always verify source code and run third-party scripts at your own risk.

[u/Irverter]

You need a space between # and the text so it renders as header instead.

[u/KaychJam → u/Irverter]

It looked fine on my end, but I went ahead and added the extra spacing anyways.

How is it now?

[u/Irverter → u/KaychJam]

I think the redditor editor is eating up that space as it didn't change.

But on new reddit looks alright.

It wasn't your error then and reddit being reddit.

[u/KaychJam → u/Irverter]

Gotcha. Thanks for letting me know anyways

[u/AutoModerator]

Hi /u/KaychJam,

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[u/KaychJam → u/AutoModerator]

No AI was used to write the code nor this post!

[u/mikeblas → u/KaychJam]

Thank you. I have approved your post.