What is mental ray shader?

mental ray shader is C/C++ code that is invoked by the mental ray core when a ray hits an object. The name ``shader'' is used by hysterical reason, I think ``Plugin'' is much better word nowadays. mental ray shader gives us a lot of freedom for users, but, I think we do not need to write a custom shader in most of the cases.

The meaning of 'gives us a lot of freedom' is when a ray hit an object, a user could almost everything by a shader. For example, when a ray hit an object, mental ray can send an email from the shader. (I believe that mental ray designer does not recommended this kind of side effect usage, but, a shader is just a plugin and it should be possible.) You can do anything means also it is difficult to handle the shaders. mental ray was developed for a long time and takes care of backward compatibility, this contributed for its complexity.

Comments

iray 2: iray in standalone mental ray

Even iray has no customized shaders, iray has a shader. It is mia_material (Arch&Design in 3dsmax) only. Actually, it is a shader that has mia_material interface and the implementation is different from mental ray (only for iray). mental images explains this is for the users who already know the mia_material. Such user doesn't need to learn the iray shader from the scratch. Therefore, some of the physically meaningless parameters of mia_material are disabled. They also said that they will support more physical shaders, like BRDF shaders. Someone asked about volume shaders support at the confenence, but, unfortunately, iray version 1 doesn't support volume shaders and will be supported in the following versions sometime. As for a DCC software user, the problem of iray is they can use it from 3dsmax/Maya/XSI or not. But NVidia's explanation is 'that is autodesk's decision.' Although, mental ray 3.8+ standalone or NVidia RealityServer support iray. (See ment...

iray 3: iray in standalone mental ray

How to export mi file from 3dsmax. 1. Assign mental ray renderer as Production renderer First open the Render Set Up dialog. Figure export_mi_1 show that opening the rollout of assign renderer and then choosing the mental ray renderer as Production renderer. Figure export_mi_1 2. Export a mi file from 3dmax. Choose Render Set Up --- Processing Tab. First you need to choose a filename as in Figure export_mi_2. Without a file name, the checkbox of 'Export on Render' is disabled. This was difficult for me. I wanted to export a file, but Export on Render is disabled. I wish I could choose the Export on Render and then see a warning message, ''an export file name is not specified.'' Next, push the Render button, then a mi file is exported. Figure export_mi_2 This is also difficult for me. When you ' export ' a file, push the ' render ' button. I wish it was like When you ' export ' a file, push the ' export ' ...

iray 1: iray in standalone mental ray

* As far as I know, we can only run mental images' iray in NVidia's RealityServer. I hope Autodesk 3dsmax/maya/xsi supports iray soon. mental images (a subsidiary company of NVidia) demonstrated iray renderer in GDC's keynote and SIGGRAPH ASIA 2009. GDC NVidia iray demo (YouTube) mental images iray page mental ray or some other renderers can simulate indirect illumination in some extent, but the methods final gather or photon map are quite rough approximation. They have no guarantee to converge to the correct answer. Also there are many renderer parameters for performance optimisation. These parameters heavily depends on the scene. It is difficult to achieve high quality and faster rendering. These methods are anyway time consuming, therefore, we sometimes put invisible light sources by hand, that simulates indirect lights. This iray is a brute force path tracer and there is no renderer parameter, but nowadays computer has not enough power to compute the light tran...

taming mental ray (English version)

Search This Blog