Leaving for Blender Conference

Tomorrow I’ll head towards Amsterdam to attend my third Blender Conference in a row. This time, besides meeting the usual lot of cool people, I’m also going to talk about my work on lightcuts — and I hope to get some useful feedback as well.

Anyway: in the last couple of days I took the time to implement some minor stuff I had been postponing for a while.

First of all, support for baking is now in. Just bake with the “Enable Lightcuts” toggle pressed: it should work now. I have to admit that this did not go through much testing, so please report any strange behavior.

A second addition was compatibility with the SSS feature from Blender Internal. Previously, it used to crash outright. Now, it gives pretty good and smooth results:

SSS + Lightcuts

SSS + Lightcuts (actually 1024 lights, not 8k as stamped)

(Apologies to Maurice R., who asked for this a long time ago… and it was actually a pretty easy fix!)

The possibility to have meshlights was another frequently requested feature. I just committed some initial code to support it.


Suzanne is the only light in this scene

It works automatically for all materials having an Emit value > 0.0. Unfortunately the object itself gets a completely flat shading. This will probably require a different handling UI-wise in the future, avoiding the Emit value altogether.

Finally, I also implemented some algorithmic improvements recently described in a paper by the original authors of the Lightcuts algorithm. According to them, this should lead to faster tree building times and better quality trees, which have in turn a positive effect on rendering times. Actually the improvements are barely noticeable most of the time but at the very least it simplifies code.

    • tuqueque
    • October 23rd, 2008

    Cool things Davide!… as i asked in BA Forum, it would be great if you could release ASAP a Windows build!… i could render a couple of images of the material Render Preview with Lightcuts ( http://blenderartists.org/forum/showthread.php?t=127215&highlight=material+preview+scene&page=2 )…

    Another thing, as a personal comment, it would also be nice if you could maintain Mesh light behavior just by manipulating the emit value and not “avoiding it altogether”… in any case, a check box here, a slider or color there… a little “refreshment” (i don’t know if that word even exist) of the emit feature would be nicer than creating confusion for new users or even worst, keep clumping Blender’s UI with more panels and redundant options.

    Greets, tuqueque.

  1. Just uploaded a Windows build :)

    Your suggestion about fixing “Emit” instead of avoiding it is a good one actually.

    Btw, your Material Render Previews are really amazing! I am curious about how they are going to behave with lightcuts… I am pretty sure you are going to unveil some interesting misbehavior ;)

    • salvis
    • October 24th, 2008

    This is really a big (and exciting) step forward for the Emit slider. Truly some awesome/expert programming skills at work. I tried it with some cubes of different colors and watch the colors blend together on the plane below them. This really allows for some nice lighting effects from objects where you can see the light itself. I tried a marble texture (both with and without colorband) to a single cube and it appears that only the underlying material color is emitted rather than the texture color(s). Is there a way to get the texture of the material with Emit so that it behaves like the textured area light, or is that feature not yet implemented?

  2. @salvis: sorry, I forgot to tell you guys a couple of current limitations. The first one is “no textures”, as you just realized :) The other one is that the emit value is interpreted as a “per area” intensity value… so very small areas (in terms of blender units) give almost no lighting. I’ll fix this stuff soon :)

    • salvis
    • October 24th, 2008

    @UncleZeiv: The “per area” thing kinda makes sense (bigger object emits more than a smaller object with same emit). Thank you for having interest in getting textures working with the emit. You have already made a great contribution to blender. I also had time to try using only the emit from a cube right next to a SSS object as sole lighting and it works pleasingly well.

  3. As for me blender is the best software

  1. October 31st, 2008