Add generic fractal noise

libs/pcg/include/psemek/pcg/fractal.hpp

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <psemek/geom/vector.hpp>
+#include <psemek/util/assert.hpp>
+
+#include <vector>
+
+namespace psemek::pcg
+{
+
+	template <typename Generator>
+	struct fractal
+	{
+		using value_type = typename Generator::value_type;
+		static constexpr std::size_t dimension = Generator::dimension;
+
+		template <typename Arg>
+		fractal(std::vector<Arg> args, std::vector<value_type> weights);
+
+		value_type operator()(geom::vector<value_type, dimension> const & p) const;
+
+	private:
+		std::vector<Generator> octaves;
+		std::vector<float> weights;
+	};
+
+	template <typename Generator>
+	template <typename Arg>
+	fractal<Generator>::fractal(std::vector<Arg> args, std::vector<value_type> weights)
+	{
+		assert(args.size() == weights.size());
+		this->weights = std::move(weights);
+		octaves.reserve(args.size());
+		for (std::size_t i = 0; i < args.size(); ++i)
+			octaves.emplace_back(std::move(args[i]));
+	}
+
+	template <typename Generator>
+	typename fractal<Generator>::value_type fractal<Generator>::operator()(geom::vector<value_type, dimension> const & p) const
+	{
+		value_type result = value_type{};
+		for (std::size_t i = 0; i < octaves.size(); ++i)
+			result += octaves[i](p) * weights[i];
+		return result;
+	}
+
+}