Calc gerstner wave in C++.

gerstner_wave.cpp

struct Wave
{
	Vec2 dir;
	float amplitude;
	float waveLength;
};

struct ImmutableCB
{
	float waveSteepness;
	float waveSpeed;
	Wave waves[20];
};

static Vec3 CalcGerstnerWaveOffset(const ImmutableCB& cb, Vec3 location, float time)
{
	Vec3 sum = Vec3(0, 0, 0);
	for (int i = 0; i < dimof(cb.waves); i++)
	{
		const Wave& wave = cb.waves[i];
		float wi = 2 / wave.waveLength;
		float rad = (dot(wave.dir, Vec2(location.x, location.z)) + time * cb.waveSpeed) * wi;
		float sine = std::sin(rad);
		float cosine = std::cos(rad);
		sum.y += sine * wave.amplitude;
		sum.x += wave.dir.x * cosine * cb.waveSteepness / (wi * dimof(cb.waves));
		sum.z += wave.dir.y * cosine * cb.waveSteepness / (wi * dimof(cb.waves));
	}
	return sum;
}