Material vs Shader

Welcome to another one of my newb questions!

Can somebody explain the difference between a material and a shader

My own ideas would probably be:

- A Material defines the texture and lighting properties of a surface, and maybe even the sound properties of a surface. Visual qualities of a material can be described with  shader(s) !

Anyway, if someone could give me some ideas here as I find the two terms quite conflicting, but its probably because of my limited understanding!

cheers :)

The reason I ask is I was thinking about making a Material class that maybe describes texture, lighting properties and sound of certain geometry.

edit: by the way I have checked out the definition of a material in the directx documentation but it only describes a material as something that has lighting properties, surely a material can go beyond this definition

Maybe material is something that was preshader :) confused...

I should have mentioned I have no problems understanding HLSL, that was not my question.

Maybe the original usage of Material is out of place with current technologies used to describe properties of a surface (shaders do this), this is my idea of material:

Glass
Wood
Concrete
Rock
Stone
Clay
Carpet
Paper
Plastic
Plant
Metal
Cloth
Fluid

This is the dictionary definition of material:

the substance or substances of which a thing is made or composed: Stone is a durable material.

The original D3D Material, in my mind is out of place with shaders, maybe LightingProperties would have been more suitable, because a material is so much more than how a surface deals with light, surely

But in meaning of 3d graphics...material is what I already said...It's a list of textures(maps also) and effects attached to 3d object.

This makes sense, although I think the definition has been outdated (at least the d3d definition is pre-shader).

In the context of XNA, there is no material anymore, why is this

Do you think sound has a place in materials (in the non computer graphics sense)

A material can emit sound when knocked, brushed, walked on etc, but materials are not the only thing that emit sound.

Yes, in some ways I am thinking of how better to organise things so they are more intuitive and obvious to what they do.

hmm that makes sense but does that mean a Material can have multiple effects

Ive been googling on surface properties, partly from how hl2 does things and also unreal.

HL2 define materials that are associated to some shader, defining what textures make up that material as well as surface properties.

On a basic level if I was to define a material in xml it could look like this:

<material name="Grass" shader="BumpMapped">
 <texture>grass.dds</texture>
 <normalmap>grassnormalmap.dds</normalmap>
 <properties>
         <sound>grass.wav</sound>
 </properties>
</material>

To be honest I dont think I want to jump right ahead and make a complex material system but just something I can start with and build on otherwise I will get bogged down in design decisions when I can always refactor as I need more.

I think at the most basic I want an easy way to define, what texture, what shader, what sound and wrap them up all in a nice abstracted way, like an xml file that I can deserialize in a pre-processing stage.

edit: by the way clyde do you want me to send you that terrain shader as a rendermonkey file It would probably be better that way then you can see it working before exporting it as an fx file, it supports a base texture and 6 detail textures + lightmap, only problem is its a 3 pass shader when I really only wanted 2 pass but I couldnt figure out how to apply the lightmap other than in a 3rd pass :(
 

Hi I sent you an email about the collaboration idea.

The only thing that concerns me about having multiple shaders per object is how to effectively organise shader code, I am also very new to HLSL but I have a few books and I understand the general principle of vertex / pixel shaders, and HLSL is a breeze to write, its just the physics and maths side of things that are not instantly in my grasp.

The only way I can think of is to dynamically build shaders in a preprocessing step to essentially optimise them for a certain usage. Its either one great uber shader that does everything, or lots of small shaders fragments that are linked together to form a final output, or even shaders that contain duplicate code.. not a good prospect. again I am very new to shaders and game programming in general, so I am not sure how to persue this until I learn more.

I think maybe distilling useful shaders into a library and not thinking to 'big' might be the way forward and live with the fact of duplicated code for now, I have the time (probably the rest of my life) to refactor, as I am not a game developer by trade and I am in no rush to be one either, I am probably to old for that :)

I quite like the way Valves VMT files work, this seems an ok way to associate textures, shaders and physical properties, I will probably start with my limited XML example above and build/refactor from there on.

Fluxtah,

I'm still learning this too but here's the way I understand it so far (not to say that I'm right, this is simply my understanding *so far*):

Materials are a combo of color, diffuse color, spec color, mirror color, alpha percentage, reflectivity and textures applied to color, mirror, spec, normal and alpha channels and they can be applied unevenly, keyed to a greyscale or color key image that tells the renderer where to apply the channel and how much by the key images levels (did I miss anything ).

Shaders are, instead, information about what color should be mapped to each vertex. Then there is the matter of exactly how the color values of pixels on the faces and edges that are in between vericies should be calculated and rendered. This is also done within the shader code.

Is there more Dunno, I haven't finished the tutes. You can follow along here:

http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series3/Starting_point.php

By the way, my idea of a "material" comes from 3D modeling... and I described most of the things that Blender uses to calculate what a given material should look like when rendered.

Good luck,

Scott