On Wed, Mar 21, 2012 at 2:14 PM, Brecht Van Lommel <[email protected]> wrote: > Hi, > > On Wed, Mar 21, 2012 at 1:42 PM, Tobias Oelgarte > <[email protected]> wrote: >> I could imagine two points in the pipeline which could be relatively >> easy expanded to do some more fancy stuff. >> >> The first point would the the transmission to the film. The color (if we >> might call it that way) of the result of a sample could be adjusted like >> inside the ramp functions for diffuse and specular inside BI, before >> combining it with the film itself. That way you could create materials >> that are seen differently as they are influencing their environment. >> This is partially possible with the help of the "Light Path" Node, but >> very limited at the same time. >> >> It would allow some kind of postprocessing coupled on the material >> itself. That way you would not need masking or indexing and a quickly >> complex getting compositing setup. A simple use case that comes to my >> mind would be toon shading. > > I don't think this would work as you might expect. Each individual > sample may be very different from the final averaged color, and in > fact depends on the particular sampling algorithm used. If for example > we can add an optimization which means we can use a single sample with > value 0.5, instead of two samples with value 0.0 and 1.0, a > modification to these values would have quite different results. > >> The second point would be the addition of the following inputs. The >> first input would deliver the angle between the surface and the current >> light ray (or even better both vectors), the second input the >> intensity/color of the light from this ray. That way the shader would >> have a great control on how light affects the surface and vice versa. >> >> It would allow unrealistic materials. For example a material that is >> basically diffuse, but becomes glossy for high light intensities. It >> could shift it's color based on the angle and so on. > > The shader is executed before lighting is evaluated, there is no light > vector available at that time. For multiple importance sampling, or > just generally GI bounces, the result of the shader is used to do > sampling to find a direction to send a ray in, which may or may not > hit a light after one or more bounces. The idea that there is a light > vector available works well for direct lighting from lamps, but once > you get to indirect lighting it doesn't fit anymore. > > This is quite different than Renderman and inspired by OSL design > which can be used successfully in production. I understand this has > limitations, there's a balance to find here between more user control > in the shader and a design where global illumination or more > intelligent sampling algorithm fit naturally without the user having > to care about them, and I believe the latter is the right choice for > this type of render engine. > > Brecht.
Seems to me he should be using the composting nodes not the texture nodes to achieve effects like this. -- Douglas E Knapp Creative Commons Film Group, Helping people make open source movies with open source software! http://douglas.bespin.org/CommonsFilmGroup/phpBB3/index.php Massage in Gelsenkirchen-Buer: http://douglas.bespin.org/tcm/ztab1.htm Please link to me and trade links with me! Open Source Sci-Fi mmoRPG Game project. http://sf-journey-creations.wikispot.org/Front_Page http://code.google.com/p/perspectiveproject/ _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
