September 7, 2010
I’ve been reading alot of technical papers and was inspired to rewrite and double check all my shaders. First, some things were broken for example, ambient color was not doing what its supposed to do. Second, I finally understood the whole linear-lighting thing and all my rgb inputs have been appropriately gamma corrected. With linear lighting, tonemapping and exposure become much more useful, so I implemented a simplified version of the Uncharted 2 “film-tonemap curve”. Third, I wanted to make it easier to do rewrites and maintain the code, so i switched the way I was working with multiple lights and inspired by rsl illuminace loop am now doing my lighting through a loop. This means I can change the code without having to worry about the number of lights or keeping track of their variables and passing them to all needed functions. I only have to initialize an array to hold that information.
lcUberShader.cgfx and lcNextGenShader.fx are now visually the same although slight differences in the languages are apparent in the code. I still recommend using cgfx over hlsl for Maya.
lcSkinShader.cgfx and lcHairShader have few changes beyond linear math option and code style changes. Some attributes have been removed or rearranged - especially with the lcSkinShader, old posts with attribute descriptions may no longer apply.
lcLitSphere.cgfx is an implementation of matcap/lit sphere shading – just for fun and in case anyone is interested.
Pictures: (click for larger)
August 26, 2010
NOTE: Apparently this script doesn't work on the Mac, I don't have one to test with so you guys are out of luck sorry.'
Now you have the option to bake vertex color as well as texture maps. This is great for baking ambient occlusion to vertices for game models. I also consolidated and simplified a lot of the code. Plus now its colorful!
August 21, 2010
Download: lcSkinShader.cgfx (save as)
Another cool shader – inspired by the Siggraph 2010 presentation 'Uncharted 2: Character Lighting and Shading' by John Hable. Its a great presentation and offers a lot of insight on how to create realistic SSS effects in shader. Unfortunately, the main topic – blurred render targets – is not possible in Maya, but the secondary techniques presented, Bent Normals and Blended Normals, are doable in Maya.
This shader takes the Blended Normals approach and adds some other elements, such as a reddish edge to the diffuse falloff, as well as uses 2 specular highlights. Also the paper describes how the Blended Normals technique results in a blue/red coloration, and the blue is not as desirable as the red, so I have implemented a very basic cyan suppression as well.
Again, a lot of attributes, but the key SSS ones are:
SSS Blended Normal Intensity – this controls the main effect of the blended normals.
SSS Edge Color – this is the color along the Diffuse Shading edge
SSS Edge Radius – this is the size of the Diffuse Shading edge coloration
SSS Edge Exponent – another tweakable parameter to adjust the reddish edge
Specular Normals Intensity – because the blended normals technique can ‘lessen’ the impact of the normal map, but overdriving the normal map intensity on the diffuse can look bad, this only overdrives the normal map on the specular highlight. Can help bring back detail.
The shadowMap and AO parts are the same as my lcHairShader.cgfx.
August 19, 2010
08/21/2010 – fixed some problems with the shadowMap texture and AO texture and vertex color code.
This one is pretty cool – I’ve been reading some of the papers coming out of Siggraph and one by the Uncharted 2 Team referenced an old 2004 paper called “Practical Real-Time Hair Rendering and Shading” by Thorsten Scheuermann. Its a really great paper and I decided to make a cgfx implementation of its hair technique for Maya. The paper is interesting because it offers a single purpose anisotropic highlight function that is specially designed for hair – using no normal maps, the only real required map is a specular map to jitter the highlight and create the ‘strands’ effect.
My Maya shader is much expanded and has a lot of functions from my previous shaders as well as some new things. Its a very versatile hair shader – although it tends to lend itself more to stylized looks than photorealism.
NOTE: Hair UV shells should all be aligned vertically – highlight orientation is based on the UV shell alignment.
There are a ton of attributes, but some of the more interesting ones are:
Main UV Texture Tiling – tiling is useful on main diffuse and specular textures to sort of set the size of the hair strands – normal map can be excluded from tiling
Hair Color – Multiplied by diffuse map – diffuse map can be B&W or colorized if you set hair color to white.
Spec Edge Sharpness – hardens the specular highlight to make it look shinier/slicker
Specular Highlight Shift – moves the highlight up and down the surface
Specular Noise Map Scale – controls the intensity of the specular jitter effect
AO in vertex color – you can bake AO into the vertex color – multiplies by the Ambient and Diffuse
Shadow Map – r is shadow for light 1, g is shadow for light 2, b is shadow for light 3, a (alpha) is AO
diffuse (multiply by hair color) – alpha is hair transparency
normal map (for big waves)
specular highlight jitter (this is normal map alpha channel)
July 30, 2010
July 8, 2010
Note: Even with this update I still recommend my lcUberShader.cgfx over this; cgfx seems a bit more stable than hlsl in the Maya viewport and cgfx shaders can be rendered through the hardware render buffer too!
I noticed that the old lcNextGenShader_1.2.fx was getting alot of hits even with updated versions and the better cgfx shader available. So i decided to update it and make it easier to maintain.
Pretty much I took the code from my lcUberShader_1.4.cgfx and transplanted it into an HLSL shader. Its missing some things from the cgfx version, lit-sphere shading, toon-ramp shading and the skin shader are removed. They where not working and I don’t think its currently worth the effort to get them working. Everything else is identical to the cgfx version and is a robust general use shader. This OLD post gives some example images from the cgfx version - blog.leocov.com/2010/03/lcubershader12cgfx.html
I’m currently investigating cross compatibility with 3dsMax – so stay tuned Max users.
July 4, 2010
Gloss Blurring Amount: – this attribute controls the blurring on the cube map reflections – previously it was default = 1.0, now it is default = 0.0. At 0.0 there is no blurring on the cubemap, even with a specular.a gloss map, but the added benefit is that if you don't have a specular.a gloss map you can still blur your cubemap, whereas before it was not possible.
Shadow Map Texture: - this is for a baked shadow map, and can use its own UV set, by default its the same UV set but you can change this under the shaders ‘Vertex Data’ rollout. Just set TexCoord2 to use something different. This is helpful because you can bake the shadows on a texture sheet that combines all your objects into one UV layout. This avoids the labor of multiple bakes.
Maya 2011: – added an empty dummy technique to the end of the techniques list, this is a temporary hacky fix for a problem in Maya 2011 where the radio buttons don’t work properly for technique selection.
March 30, 2010
This update to my Mental Ray texture baking script streamlines some of the code and adds some minor features.
You can now type in the Output Directory with less fuss – the script will parse forward and backward slashes – and will create the necessary ‘lightMap’ folder if it is not present.
Added a button to open the selected (from the dropdown list) bake set in the attribute editor.
Created a handy shelf icon.
March 12, 2010
This exposes some simple attributes about the currently active camera to the user in a small interface. It avoids having to dig around in the attribute editor. The attributes in the script will update for the current camera when the script window is given focus (clicked on).
1. Create a useful Maya viewport shader with many interesting functions and techniques to showcase a wide range of surfaces.
2. Write a Shader with a compartmentalized structure that is easy to read and dissect for people learning the basics of shader code.
This shader is quite large and complex and because of the decision to compartmentalize much of the code into distinct functions it is not performace optimized.
You must link 1-3 directional lights into the light slots at the bottom of the attribute list – I would recommend you use my lcRTShaderTools.mel to interact with the shader.
lcBasicShaderComponents.cgfx (this is a basic stub shader for people learing cgfx and wanting something simpler to start out)
BasicTextures.zip (some basic textures for use with the lcUberShader – don’t quite remember where they all came from – thank you to the original creators)
* Although I provide 8-bit alpha support, Maya has transparency sorting issues when in this mode.
* Because there are so many attributes the Maya Attribute Editor can sometimes momentarily stall when updating/opening or switching techniques
* Only 1 input is available for an environment cubemap (this serves for both reflections and ambient color) – the shader assumes this cubemap is a properly filtered cubemap made with ATI’s CubeMapGen tool and that it has mipmaps
* When you are in Toon or LitSphere Techinques the shading color will be multiplyed by the Diffuse Texture, you can scale the contribution of the Diffuse Texture with the Diffuse Color Attr – but you cannot tint it.
* Cubemap and Hemispherical ambient color is multiplied by the Ambient Color Attr, it must be something other than black for those effects to show up.
Please use this as inspiration for writing your own shaders, the code is very easy to take apart, rearrange and unfold. I have tried to comment the code in key places of interest. I also included a more basic shader with the same coding structure as a starting point for people interested in learing.
This script makes it easier to interact with HLSL and CGFX shaders in Maya. It performs shader naming, creation/sourcing, light linking, and other helpful tasks.
This update adds light rig scaling – depending on how a hlsl or cgfx shader is coded, scaling your lights can result in incorrect lighting. The ‘Light Rig Scale’ attribute moves the lights and scales their locator handles to give the visual impression of a ‘scale’ operation. (you can Ctrl+MiddleClick and horizontal drag this box to interactively scale).
CGFX and HLSL shaders will only work with this script if their light position/direction and light color attributes are named properly in the shader file.
Convention: light attribute names should be as follows - 'light1Dir' or 'light1Pos' and 'light1Color'
ambient color/light attribute on the shader should be – 'ambientColor'
lcRTShaderTools.zip (includes shelf icon)
February 27, 2010
I am particular to command line tools and Nvidia offers us a nice and simple tool for .DDS compression.
Its super fast and runs on the GPU through CUDA (although that means you need the proper hardware and drivers)
nvcompress.exe is the particular tool I’m looking at here but there are a few other cool utilities included too.
You can get direct and simple access to the tool through Photoshop by running some simple scripts.
How to Install:
put the *.js files here /Adobe Photoshop CS*/Presets/Scripts
run from File > Scripts menu
(you must have nvcompress.exe’s filepath in your PATH Environment Variable or this wont work out of the box)
How it Works:
It saves a temporary copy of the currently selected Photoshop document to a .tga
It creates temporary .bat script containing the command line arguments for nvcompress.exe
Runs the .bat script on the temporary .tga and spits out a new file into the same folder as your original document (with the ‘filename’_DXT5.dds naming convention)
These scripts are very easy to edit, and can be made to run multiple compressions in sequence.
Documentation and command line arguments are available here:
Take it – run with it.
Special thanks to Fredrik Brännbacka who posted Save As Map.js on CGTalk a few years ago – from which this script is directly based.
February 20, 2010
Maya Real Time Shader Tools Mel Script
I've been developing a mel script to make it easier to create/assign/interact with hlsl and cgfx shaders in maya. Linking lights, changing light colors, making sure you have the correct .mll's loaded - providing an easier interface for managing lights.
I made this originally for my fellow production artists at work - so they would actually use the CGFX/HLSL shaders that mimic our game engine - because otherwise its a bit complicated to set them up (artists are picky and fickle I know!)
It should work with any CGFX or HLSL shader as long as certain conditions are met, these are: light attribute names should be as follows - 'light1Dir' or 'light1Pos' and 'light1Color' ambient color/light attribute on the shader should be - 'ambientColor' (why no light intensity? light color value can easily be overdriven to accomplish the same thing)
Works with up to 3 directional or point lights (mix and match)
Sample Shaders for testing:
I've done as much testing as I can reasonable stand on this script - I don't make any promises but myself and my fellow artists have found it helpful.
Eventualy I'll get around to translating my HLSL shaders to CGFX and adding fancy features. If you like writing mel scripts please feel free to use this script as a starting point or inspiration.