What I was thinking about when writing the statement about modern gpus was that the algorithm described here was mainly constrained by the limited number of blend modes available in the old fixed function pipeline. I haven’t thought about improving it in detail. Using vertex buffers and some sort of spacial tree data structure for the lights would definitely make sense though.

As for overbrightening: floating point textures would work. You can also continue to use ARGB32 and change the pixel shader used for blending the lights onto the scene to do a scaled multiplication (something like result_color = 2 * unlit_color * light_amount) . You’d lose some accuracy and would have a maximum amount of overbrightening, but that’s probably ok.

If you release your code somewhere, let me know! People have been asking for a C++ implementation quite a bit.

Also I think there are two limitations right now with this method. First, you can’t get overbrighting effects as described in the original article. I solved this by rendering the whole scene in a seperate fbo and blend it over each light, but I think this is not the most optimal way of doing it. It would be ideal if you could somehow save color values greater than 1 in a fbo, but I don’t know how.(maybe floating point textures or something)
Second, this currently only works if the lights size is smaller than the shadowblockers. I think this can be solved by rendering both the penumbras and umbra in full darkness and then subtracting the areas of the penumbras appropriately.

Anyways, this helped me a lot, I am only interested in knowing what can be improved to make it even better. This is how my implementation looks right know, you can also see the mentioned overbrightening effects:
http://www.iamwhoiam.net/max/shadow-test2.ogv

for (size_t i = rightpenumbra.sections.size() - 1; i < blockerLine.size() - leftpenumbra.sections.size() + 1; ++i) {
    Vert &vert = blockerLine[i];
    umbra.sections.push_back(Umbra::Section(vert, extendDir(0.5 * (leftpenumbra.sections.last().direction + rightpenumbra.sections.last().direction)));
}

Would you mind converting this line to me, I can’t understand the loop, begins where and finishes where?

foreach(ref vert; blockerLine[rightpenumbra.sections.length-1..$-leftpenumbra.sections.length+1])
umbra.sections ~= Umbra.Section(vert, extendDir(0.5 * (leftpenumbra.sections[$-1].direction + rightpenumbra.sections[$-1].direction)));

I’m also having some troubles on other parts but for now this would help a bunch. I’ve placed my email on the form.
Thanks

Thank you. Your sample codes really helped me in trying to achieve the effect. I would have no idea how/where to start by just reading orangy’s article.

Cheers :)

Unfortunately I don’t have the time to help debug your problem. Start small, build things step by step and test everything along the way.

Would be great if you can help.

FYI, great article. Helped me a lot :)