Mandelbox DE formula

[khyperia]

This formula, a modified one from http://blog.hvidtfeldts.net/index.php/2011/11/distance-estimated-3d-fractals-vi-the-mandelbox/, isn't working. Well, for scales above 1, it is, but for negative scales it isn't. Personally, I think negative scale mandelboxes are better, so I really want to get this working. I've basically narrowed the problem down to this core forumla. (Language is C#, 100% my own program (excluding the copy-pasta'd formulae), example render http://khyperia.tumblr.com/post/20060287683/moar-renders)

Code:

public static float DistanceEstimator(Vector3 z)
        {
            Vector3 c = z;
            float dr = 1.0f;
            for (int n = 0; n < Settings.maxIterations; n++)
            {
                if (z.X > 1)
                    z.X = 2 - z.X;
                else if (z.X < -1)
                    z.X = -2 - z.X;
                if (z.Y > 1)
                    z.Y = 2 - z.Y;
                else if (z.Y < -1)
                    z.Y = -2 - z.Y;
                if (z.Z > 1)
                    z.Z = 2 - z.Z;
                else if (z.Z < -1)
                    z.Z = -2 - z.Z;

                float r2 = z.LengthSquared();

                if (r2 < 1)
                {
                    if (r2 < 0.25f) // 0.5 squared
                    {
                        z *= 4;
                        dr *= 4;
                    }
                    else
                    {
                        z /= r2;
                        dr /= r2;
                    }
                }

                z = Settings.scale * z + c;
                dr = dr * Settings.scale + 1.0f;
            }
            return z.Length() / Math.Abs(dr);
        }

Can anyone spot an error that would screw negative scales up?

[bib]

the copy-pasta'd formulae

That must be Darkbeam's formula for sure (the spaghetti coder)

[Syntopia]

Hi,

For negative values, you'd need the abs(scale) for the running derivative:

Code:

 dr = dr * Math.abs(Settings.scale) + 1.0f;

[DarkBeam]

That must be Darkbeam's formula for sure (the spaghetti coder)

Oh well, somebody tries to imitate me ... Curse him! :evil:

[David Makin]

That must be Darkbeam's formula for sure (the spaghetti coder)

Darkbeam's code....spaghetti

You have seen my UF code ?

[DarkBeam]

It is well done! Mine is the worst possible trust me!