What is a shader?

Sertorial

In the lights and camera activity under Presets, it has lights presets and shader presets. Lights presets (I presume) are just a combination of different lights, but what is a "shader"?

Scott Livingston

My quick layman's definition: something that controls how a surface looks and how it reacts to light. An example of one of the many things a shader can control is glossiness.

Here's a more detailed definition, taken from the Glossary of Terms:

Shader: A computer program used to determine the final surface properties of an object or image. This often includes arbitrarily complex descriptions of light absorption, diffusion, texture mapping, reflection, refraction, shadowing, surface displacement and post-processing effects. In real-time shading languages there are two different applications of shaders: vertex shaders and pixel shaders.

Shading (“Shader” or “shading algorithm”): The mathematical process of calculating how a model’s surfaces react to light. A variety of alternative algorithms can be used for the task, including Phong, Lambert, and Blinn shading models. Shaders are often built up as node-based shading trees, with each node controlling a specific aspect of the process.
A high-level rendering algorithm that determines how a 3D model responds to simulated light. Sometimes called a “shader.” Strictly speaking, a shader or shading algorithm is a piece of computer code that is part of a material definition. For example, the Blinn shading algorithm generically describes how highlights appear on surfaces. However, many 3D graphic artists use the term “shader” to refer to an entire material definition, including all of its component parts such as bitmaps.

Sertorial

Scott-Livingston said:

My quick layman's definition: something that controls how a surface looks and how it reacts to light. An example of one of the many things a shader can control is glossiness.

Here's a more detailed definition, taken from the Glossary of Terms:

Shader: A computer program used to determine the final surface properties of an object or image. This often includes arbitrarily complex descriptions of light absorption, diffusion, texture mapping, reflection, refraction, shadowing, surface displacement and post-processing effects. In real-time shading languages there are two different applications of shaders: vertex shaders and pixel shaders.

Shading (“Shader” or “shading algorithm”): The mathematical process of calculating how a model’s surfaces react to light. A variety of alternative algorithms can be used for the task, including Phong, Lambert, and Blinn shading models. Shaders are often built up as node-based shading trees, with each node controlling a specific aspect of the process.
A high-level rendering algorithm that determines how a 3D model responds to simulated light. Sometimes called a “shader.” Strictly speaking, a shader or shading algorithm is a piece of computer code that is part of a material definition. For example, the Blinn shading algorithm generically describes how highlights appear on surfaces. However, many 3D graphic artists use the term “shader” to refer to an entire material definition, including all of its component parts such as bitmaps.

Right. Ok. Thanks for that.

So if I have a scene and I apply one of the shader presets to it (my DAZ came with two presets, HDR KHPark and HDR kitchen) it will change how my distant lights, or spotlights actually interact with the image?

Do I have to apply it to something specific? Like a light, or a DAZ figure?

Scott Livingston

I don't have DAZ Studio in front of me at the moment, but my understanding is that those are only for use with UberEnvironment lighting (they're applied to the surface of the UberEnvironment sphere).

Edited to add: you should have other shader presets that came with the software, but you may need to select a surface (using the Surface Selection Tool, or by going to the Surfaces Tab) to use them.

Sertorial

Scott-Livingston said:

I don't have DAZ Studio in front of me at the moment, but my understanding is that those are only for use with UberEnvironment lighting (they're applied to the surface of the UberEnvironment sphere).

Edited to add: you should have other shader presets that came with the software, but you may need to select a surface (using the Surface Selection Tool, or by going to the Surfaces Tab) to use them.

ok, thanks

Probably too advanced for me just now (don't understand Uber Environment).

I'll just stick to children's lights for the time being

Scott Livingston

Yeah, just take it one step at a time. :) Personally I found it helpful to use light presets for a while, before wandering into the realm of customized, do-it-yourself lighting, but different people have different learning systems and strategies. There are some great lighting products in the store...Lantios Lights 2 is one I can vouch for, but I know there are plenty of other good ones by that vendor and others. Sometimes I use the light presets as-is, other times I tinker with them.

This thread (which I know someone else has already recommended to you, in a different thread) is really helpful for learning UberEnvironment, but it can get pretty technical. I'm still working my way through it... http://www.daz3d.com/forums/discussion/5320/