2d0adb92cc
math.fbm(p, octaves, lacunarity, gain) and math.fbm(p) (four octaves, lacunarity 2, gain 0.5); cultmath_fbm in the shaders, the GLSL regenerated by GlslLowering, a golden-fixture family appended, FbmTests for the rules. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
73 lines
2.2 KiB
C#
73 lines
2.2 KiB
C#
using System;
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using CultMath;
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using Xunit;
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namespace CultMath.Tests;
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public sealed class FbmTests
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{
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private static float3 Point(System.Random r) => new(r.NextSingle() * 20.0f - 10.0f, r.NextSingle() * 20.0f - 10.0f, r.NextSingle() * 20.0f - 10.0f);
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[Fact]
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public void OneOctaveIsSnoise()
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{
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var random = new System.Random(0xFB01);
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for (var i = 0; i < 64; i++)
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{
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var p = Point(random);
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Assert.Equal(math.snoise(p), math.fbm(p, 1, 1.0f + random.NextSingle() * 3.0f, 0.1f + random.NextSingle() * 0.8f));
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}
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}
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[Fact]
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public void ZeroOrNegativeOctavesSumNothing()
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{
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var p = new float3(0.3f, 1.7f, -2.2f);
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Assert.Equal(0.0f, math.fbm(p, 0, 2.0f, 0.5f));
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Assert.Equal(0.0f, math.fbm(p, -5, 2.0f, 0.5f));
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}
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[Fact]
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public void OctavesCompoundGainAndLacunarityIndependently()
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{
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// gain != lacunarity and neither is 1, so applying either once, or swapping them, changes the sum.
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const float lacunarity = 2.3f;
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const float gain = 0.4f;
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var random = new System.Random(0xFB02);
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for (var i = 0; i < 64; i++)
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{
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var p = Point(random);
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var expected = math.snoise(p) + gain * math.snoise(p * lacunarity) + gain * gain * math.snoise(p * (lacunarity * lacunarity));
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Assert.Equal(expected, math.fbm(p, 3, lacunarity, gain), 5);
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}
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}
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[Fact]
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public void ValueIsFbmGradsValue()
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{
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var random = new System.Random(0xFB03);
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for (var i = 0; i < 128; i++)
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{
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var p = Point(random);
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Assert.Equal(math.fbm_grad(p, 5, 2.0f, 0.55f).w, math.fbm(p, 5, 2.0f, 0.55f), 4);
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}
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}
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[Fact]
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public void OctaveCountClampsToSixteenLikeFbmGrad()
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{
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var p = new float3(0.3f, 1.7f, -2.2f);
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Assert.Equal(math.fbm(p, 16, 1.1f, 0.9f), math.fbm(p, 1000, 1.1f, 0.9f));
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}
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[Fact]
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public void OneArgumentFormIsFourOctavesLacunarityTwoGainHalf()
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{
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var random = new System.Random(0xFB04);
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for (var i = 0; i < 64; i++)
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{
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var p = Point(random);
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Assert.Equal(math.fbm(p, 4, 2.0f, 0.5f), math.fbm(p));
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}
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}
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}
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