Textures in custom shader feature

#1 Could you give me a description of what you are trying to accomplish in the end? Are you just writing a custom shader to display a diffuse texture (First Step in making sure you shader is working?) Sorry for the confusion I just want to make sure I find a good answer for you :O)

#2 Hey Andy,in the old days I did a resource on how to add a new shader feature.Check my profile.
If you need to read and sample a texture just see how the other maps (normal,specular,etc...) are loaded.

Here is an example:

// the map
Var *bumpMap = new Var;
bumpMap->setType( "sampler2D" );
bumpMap->setName( "bumpMap" ); // bumpMap !!!
bumpMap->uniform = true;
bumpMap->sampler = true;
bumpMap->constNum = Var::getTexUnitNum();

//the sampler
bumpSample = new Var;
bumpSample->setType( "vec4" );
bumpSample->setName( "bumpSample" );
LangElement *bumpSampleDecl = new DecOp( bumpSample );
         
// the injection
output = new GenOp( "   @ = texture2D(@, @);rn", bumpSampleDecl, bumpMap, texCoord );

You don't need to call the previous call all the time.
Once registered,try to find it this way:

Var *normalMap = (Var*)LangElement::find( "bumpMap" );

The var "bumpMap" is assigned this way:

mBumpMapTexSC = shader->getShaderConstHandle(ShaderGenVars::bumpMap);

Where mBumpMapTexSC is a Shader Const Handle.

In shaderGenVars.cpp add

const String ShaderGenVars::bumpMap("$bumpMap");

Features are batched into several groups,I think you should use the MFG_Texture group.
All this stuff is a bit tricky.

#3 Well ultimately I will be combining a couple of normal maps to show "defects" on my object. Ideally there will be another map that controls how the other normals are blended.

So, I would like to be able to assign a "DefectMap" to features, but I can't *quite* figure out how to make it load textures it isn't already "expecting". I'm missing a step somewhere.

#4 Thanks Ivan, I'll take a look at that resource.

#5 There are several directives,that declare ,implement and register a new feature. Check this out.
When a new texture is used,(I am not really sure if it is necessarily or not),Torque is using getResources() to pull new resources.It is part of the shaderFeature class.
getResources() is connected to MaterialFeatureData,that contains data about the material stage.
When you create your feature,you must overload this method and add an information about the number of textures used in your hlsl injection.

ShaderFeature::Resources YourNewFeatureHLSL::getResources( const MaterialFeatureData &fd )
{
   Resources res; 
   res.numTex = 1; // how many textures are used
   res.numTexReg = 1; // how many registers are used to pass data
   return res;
}

If you are using SM2 or SM3,each texture corresponds to a single sampler register.If you use the sampler several times, numTexReg < numTex,because you sample several times using a single register.
All this stuff depends on your shader feature.The basic case is one register and one texture.Below SM2 sampler registers(S#) are not supported (by the gpu) therefore more registers are used (numTexReg > numTex).