RE: SDK: mental ray shader doesn't recognize scene light list

[Matt Lind]

Update:

Renderer Options set in the shaderdef don’t seem to be getting pushed to mental 
ray at all.  Not only is the light list not getting properly wired up, but the 
‘trace’ and ‘derivatives’ flags I set in the renderer options of my material 
shader don’t get wired up either.  When I query for those specific flags using 
mi_query() in the shader _init() or _main() functions, the flags are not set.  
I have attempted this in Softimage 2013 SP1 and Softimage 2014 SP2 with 
identical results.  I have also attempted to port my shaderdef to JScript to 
see if it is a language problem.  same results...although PPG logic works 
better in JScript.

Am I doing something fundamentally wrong, or is this a bug?


Matt










I am updating some mental ray shaders I wrote many years ago.  

When using a .spdl for the UI and making the most minimal of tweaks to my C++ 
code to be compliant with the current version of mental ray, the shaders render 
as expected.  However, when using a ShaderDefinition to define the UI and 
registration, the scene light list is always empty resulting in dark rendered 
images.

Code snippet illustrating how I’m declaring the scene light list in the shader 
definition (C++):

    Context oContext( oContextRef );
    Factory XSIFactory = Application().GetFactory();

    // Shader definition
    ShaderDef oShaderDefinition = oContext.GetAttribute( "Definition" );    
    oShaderDefinition.AddShaderFamily( siShaderFamilySurfaceMat );
    oShaderDefinition.AddShaderFamily( siShaderFamilyShadowMat );
    oShaderDefinition.AddShaderFamily( siShaderFamilyPhotonMat );

    // Parameter definitions    
    ShaderParamDef oParameterDef;
    ShaderParamDefOptions paramOptions;
    ShaderParamDefContainer oParametersInput  = 
oShaderDefinition.GetInputParamDefs();
    ShaderParamDefContainer oParametersOutput = 
oShaderDefinition.GetOutputParamDefs();    

        // Add light list parameter
    paramOptions = XSIFactory.CreateShaderParamDefOptions();
    paramOptions.SetLongName( L"lights" );
    paramOptions.SetAnimatable( true );
    paramOptions.SetTexturable( true );
    paramOptions.SetReadOnly( false );
    paramOptions.SetInspectable( true );
    paramOptions.SetAttribute( siReferenceFilterAttribute, 
siLightReferenceFilter );

    oParametersInput.AddParamDef( L"lights", siShaderDataTypeReference, 
paramOptions );   


The light list as defined in my mental ray shader code.  Works correctly with 
.spdl files, but fails without warning or error when using shader definition 
files:

    typedef struct
    {
       // Light list
       int   i_light;     // memory address of first light in light array
       int   n_light;     // number of lights in the light array;
       miTag lights[1];   // pointer to light array
    } ml_shader_params;


when I dump the number of lights in the scene via mi_info(), it returns the 
expected number of lights in the scene when the shader is registered using 
.spdl, but always returns zero when registered using a shader definition:

    miInteger NbLights = *mi_eval_integer( & paras->n_light );   // number of 
lights in light list

    mi_info( “Nblights: %d\n”, NbLights );



Anybody know what the secret handshake is to get light lists to be recognize by 
a mental ray shader when using shader definition files (C++)?  I would really 
like to ditch the .spdl format if possible.

thanks,

Matt