I implemented a very crude photon map in Manta a year ago for a project
which kind of fizzled out.  It was pretty simple to implement,
especially if you are familiar with Manta.  I don't see it in my project
directory so I might have accidentally deleted it though.  I think I
just ended up making a custom material type and building the photon map
as a pre-computation step using a flag that tells the material to bounce
the ray and add it to a kdtree.  If I remember correctly there is
already a random sampling for the lights; I think I used that function
to generate rays from the light sources.  There is a BRDF class already.
I think the main things were building my own basic kdtree for sample
lookup (I don't think I was easily able to adapt the existing kd-tree
for storing samples for k-nearest but I could be remembering that wrong
or was just being lazy) and filtering.

what is this engine for?

Carson

On Wed, 2010-09-29 at 10:03 -0600, James Bigler wrote:
> I'm not sure how to get Manta to switch between different Cameras, but
> you might be able to implement the photon pass as a camera and
> material set, build your photon map, and then use another camera and
> material set for the gather pass.
>
> As an alternative to Manta, NVIDIA's OptiX
> ( http://developer.nvidia.com/object/optix-home.html ) has a
> progressive photon mapping sample:
> (windows one click samples:
> http://developer.nvidia.com/object/optix-examples.html).  OptiX
> requires a CUDA capable device, but it should work on
> Windows/Linux/Mac.  The SDK has precompiled binaries for each
> platform.
>
> James
>
> On Wed, Sep 29, 2010 at 9:49 AM, < "> > wrote:
>
>         Hello,
>
>         I am relatively new to ray tracing and it was suggested that I
>         consider Manta
>         for my engine development.  I have been impressed by the
>         architecture and
>         features but was curious whether photon mapping (or other
>         forward ray tracing
>         concepts) had been incorporated into the existing Manta
>         release.  A post from
>         March 17, 2010 suggests that forward ray tracing techniques
>         would still need to
>         be developed.  Is this accurate?
>
>
>                Off the top of my head, Manta has a simple (brute
>         force) path tracer,
>         it can do soft shadows (outside of the path tracer as well),
>         and also ambient
>         occlusion. And of course if it doesn't have something you can
>         add it. I am not
>         aware of Manta currently having bidirectional path tracing,
>         metropolis light
>         transport, photon mapping, or any of the other fancy GI stuff.
>                Thiago
>
>         Thank you,
>         Daniel
>