When rendering with specular highlights, I like how points can be culled because they don’t face the light, but I’d like an option to render all the points, and just shade the unlit points as black.
I’m getting some really weird results where some objects aren’t getting their back sides rendered, and everything seen “through” that area is overly bright because it isn’t being occluded by the unlit particles.
Wouldn’t it make more sense to just have the particles be two-sided?
How do I do that?
Sorry, I phrased it as a suggestion instead of a question. I was mostly just wondering if there is any benefit to having back facing particles render black, instead of treating them as a two-sided disc. I’m working on that stuff right now, so you should see it show up in the next beta.
Just a note that the current behavior IS to shade back-facing particles as black - nothing gets culled, they just merge with the background if it is black.
So we propose to support the old behavior (shade black) and add a new behavior (force 2-sided) where backfacing particles will be considered front-facing and will be lit as long as any light is reaching them.
that’s not what I am seeing. when the points aren’t lit they don’t contribute to the alpha channel. maybe a bug then. not a huge deal, I can wait for the next beta. the workaround isn’t bad.
-Chad
Strange. I created a plane with 200x200 segments, placed an omni above it and enabled Normals.
When rendered from above, the vertices are shaded with specular highlights. When rendered from below (backfacing normals), I get black RGB but white alpha. If I move the omni light underneath, I still get that because the normals are facing away, but alpha is still white.
Again, I don’t need this fixed for 1.1, but I’m sending a file so you can see if this bug exists in 1.2 or not.
Seems to be related to the specular glossiness. If the glossiness is high, it works as we would expect. But if the glossiness is low, you start to lose points.
Reminds me of the "Hot lights burn away points problem we had in the past, especially since it “corrupts” the PCache, actually deleting the points, so that if you turn on PCache, render, then turn off “Use Lighting”, the points are gone.
Thanks for the file!
Sounds like a bug, we will look into it.
1.2 is performing the specular shading differently now - it is done as part of the Final Pass so it won’t affect the Caches in memory anymore. This means that you could cache your particles, animate the camera and still get correct view-dependent effects like highlights and environment reflections. In 1.1 and earlier, the specular highlights were part of the Lighting Pass and were baked into the lighting channel. This might have fixed the bug as a side effect, but we will check.