Orchid Win7 v1 <voi### [at] devnull> wrote:
> On 04/07/2015 07:43 PM, Samuel Benge wrote:
> > Orchid Win7 v1<voi### [at] devnull>  wrote:
> >> After spending a while Googling this, is appears that "ray marching" is
> >> simply another name for the sphere tracing technique that POV-Ray uses
> >> to render isosurfaces already.
> >
> > Sphere tracing? As a bounding shape for the distance estimate (shape) function,
> > or as the basis for all DEs?
>
> This of course is thwarted by functions that are extremely steep at the
> edges, yet quite shallow near where the solutions are. [*cough*
> Mandelbrot set *cough*] You end up needing an insanely high
> max_gradient, yet in the vicinity of the solutions you could actually
> afford to take much bigger steps.

One thing that helps is to use log log smoothing for the exterior. It helps, but
it's slow. And I could never find a successful way to multiply or divide a
fractal's gradient in order to speed things up.

> > And something is broken with POV-Ray's isosurface. I remember a time when it
> > used to have fewer artifacts.
>
> It depends on the function you're trying to trace, and the configured
> max_gradient.
>
Well, flat-sided objects rendered more quickly and without artifacts once upon a
time (before 2003 or 2004).

> >> If only it wasn't so damned hard to program GPUs. This stuff sounds fun...
> >
> > Not hard but rather easy, if you have a graphics library at hand that supports
> > OpenGL. I use SFML (C++, other bindings might be available), which is geared
> > towards 2D graphics. I just use a simple sprite (quad) and use render textures
> > along with GLSL shaders. (It also helps to get a vector math library, as SFML's
> > transformation class is not good for 3D). Getting something set up is easy, you
> > just need to learn GLSL, which is really a fun language to use.
> >
> > Another good thing about SFML: it's open source, so you can compile it yourself.
> > (I had to do this to add support for 16 and 32 bit textures.)
>
> In my day job, I have trouble just making C++ *compile* and *link*
> successfully, never mind actually run without segfaulting. Kind of
> amazing I had paid for this...

Dude, I'm an amateur, and I can compile & link C++ programs and libs all day
long, no problem. OK, /some/ problems, sometimes :D Are you overthinking the
whole thing? That's usually what causes those sorts of issues for me :/

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