I’m trying to do something but could not fin appropriate help anywhere…
I need translucency on a material - for instance, leaves (as distorted planes actually) textured on both sides with the appropriate nodes.
More precisely, I don’t really need translucency for the leaves’ aspect, but to transmit the sun’s light beyond the leaves, thus lighting up the trunk and branches under them, which are pitch black without that. But I can not diasable shadows altogether : I still need some shadows to be cast under the leaves, were it only diffuse. On the other hand, I absolutely do not want transparency, since leaves are not transparent. I tried to set some translucency in the material tab, but to no avail : even 100% translucency has no effect.
Is there a way to do that in Blender internal render? If not, can Cycles do it? (I’m not doing ultra high-quality renders so if I can stick with blender internal I will…)
Not something I use much, but isn’t translucency a shader for letting light shine through to backfacing faces? Try using transparency for shadows only (texture mapped) and just let translucency do its thing for the backside.
Hmm, I’m not sure to understand… I could use partial transparency to cast partial shadows, but then the leaves themselves would be partially transparent, which is not something I want… Or am I missing something?
I’m in Cycles mode btw, and the logics I’m thinking of would for a leaf be something like:
Light green diffuse.
Dark green translucent.
Add shader them together.
Darker transparent shader, with black areas for complete shadow rather than colored shadow.
Mix this with the previous add using IsShadowRay (transparent in bottom slot).
White transparent shader.
Mix this with previous mix using your leaf mask of choice.
Add bump and color textures as needed.
Basically I think you’re overestimating what the translucency shader is meant for (assuming I’m getting it right :D, anyone feel free to correct me): Translucency doesn’t do anything with shadows cast from the translucent surface. It allows light to shine through to the unlit side (but not beyond that) and have shadows on the backside cast from objects in between the frontside and the lightsource. Color of the translucent materials shadow will remain black, and you can only control this using the transparent shader, but limit its effect to be visible to shadow rays only. Pretty much the same effect you would do to create fake glass shadows and fake glass caustics (by causing shadows to be whiter than white in certain areas).
Thanks, but actually I already managed to obtain the good result in cycles… I’m just trying to see if I can keep using BI render, because Cycles, although beautiful, needs really long render times to avoid a swarm of fireflies…
Thanks for the heads up, I was actually vastly overestimating what translucency was supposed to do
I feel that the solution is at hand here, but I fail to see how I can make Blender apply the transparency factor only to the shadows (in BI render)?
I’ve never used BI much so I wouldn’t know. But here is a quick mockup I did in Cycles. Note that the textures aren’t ideal so I had to use some extra nodes to get the values I wanted for certain things, and I did crank up the sunlight considerably - a balancing thing that wouldn’t be necessary with suitable textures.
So the shadow of the “plank” in front of the leaf cast a shadow which is shown on the backside. Diffuse lights the lit side, and translucency lights the unlit side. The first transparent shader causes color variation in the shadow the second is just masking out the complete leaf. If this was real I would probably make two of these (prior to the mask), one for the upside of the leaf and one for the underside. Also I didn’t bother adding any glossy.
Can’t really help much more since I don’t do BI. I searched for translucency tutorials (cycles) but didn’t find much detailed info.
Thanks, those 2 examples are awesome. Maybe Roken’s one is closer to my needs because it’s simpler and I don’t need a high level of detail or translucency on the leaves themselves, I just need that their shadows do not blot out the trunk completely…
I don’t know though if I can obtain the same result with BI render’s nodes, they are not as powerful as Cycle’s ones it seems. And since they are not either labelled identically, I have some trial and error ahead… unless someone speaks BI nodes fluently here (if I really have to switch to Cycles I will… reluctantly!)
To be honest, I used a simple emission shader just for demonstration purposes. You can replace that one node with something as simple or as complex as required.
By way of example, this object has 3 materials applied, and the dialetric is a whole node group in itself.
Thanks for the input. So, after many trials and errors, I finally decided to switch to cycles to render the objects, while retaining the possibility to use BI for the shadows on another layer, because why not (I don’t like Cycles blurry shadows).
One question Roken : what’s the use of the “dielectric” node there? I must admit I don’t really understand how your diagram works…
Those “dielectric” nodes are probably PBR’ish nodes doing a regular material shading effect (typically fresnel mixing diffuse and glossy).
I haven’t tried the above setup, but would it work correctly with a reflective floor or through a transparent/refractive glass pane?
(if I really have to switch to Cycles I will… reluctantly!)
