UnrealEngineUWP/Engine/Source/Developer/SynthBenchmark/Private/FractalBenchmark.cpp

// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

#include "SynthBenchmarkPrivatePCH.h"

// simple float ALU heavy benchmark
// no dependency on any math library

uint32 EvaluateJuliaFractalAt(float X, float Y)
{
	uint32 Ret = 0;

	float dist2 = 0;
	const float maxdist2 = 1600;
	uint32 MaxIter = 300;

	// pretty Julia fractal
	float Cx = -0.73f;
	float Cy = 0.176f;

	while(dist2 <= maxdist2 && Ret < MaxIter)
	{
		float X2 = X * X - Y * Y + Cx;
		float Y2 = 2 * X * Y + Cy;

		X = X2;
		Y = Y2;

		++Ret;
		dist2 = X * X + Y * Y;
	}

	return Ret;
}


float FractalBenchmark()
{
	// scales quadratic with the time
	const int32 Extent = 256;

	int32 Count = 0;
	float Sum = 0;

	for(int y = 0; y < Extent; ++y)
	{
		for(int x = 0; x < Extent; ++x)
		{
			Sum += EvaluateJuliaFractalAt(x / (float)Extent * 2 - 1, y / (float)Extent * 2 - 1);
		}
	}
	
	// to avoid getting optimized out
	return Sum / (float)(Extent * Extent);
}