dynamcially created data structure

Discussion in 'C++' started by Christopher, Oct 9, 2008.

  1. Christopher

    Christopher Guest

    Is it possible to dynamically create a data structure?

    Not that it matters, but just for understanding, I am working with
    video shaders, these shaders use thier own language (HLSL) which you
    compile at runtime and run for rendering. The HLSL can contain many
    differant types of variables and expect your application to set them.

    The library provides the ability to query for
    number of variables
    thier names
    thier types
    and provides a method for setting them that is depedent on the type

    My goal is to package them, no matter what they are, into a single
    material class, that can be used no matter what the HLSL it
    corresponds to looks like.

    So, I want the same data structure that is capable of setting, for
    example, two floats in one case, a float and a string in another case,
    7 floats and an array of UDTs in another case, etc.


    My first thought was to create a class that had a one map for every
    possible type, but I am not sure that is the best.

    I was also thinking of making seperate "Material Property" classes
    that could be added and removed from a "Material", but its fuzzy.

    Any ideas?
     
    Christopher, Oct 9, 2008
    #1
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  2. Christopher

    Ian Collins Guest

    Christopher wrote:
    > Is it possible to dynamically create a data structure?
    >
    > Not that it matters, but just for understanding, I am working with
    > video shaders, these shaders use thier own language (HLSL) which you
    > compile at runtime and run for rendering. The HLSL can contain many
    > differant types of variables and expect your application to set them.
    >
    > The library provides the ability to query for
    > number of variables
    > thier names
    > thier types
    > and provides a method for setting them that is depedent on the type
    >
    > My goal is to package them, no matter what they are, into a single
    > material class, that can be used no matter what the HLSL it
    > corresponds to looks like.
    >
    > So, I want the same data structure that is capable of setting, for
    > example, two floats in one case, a float and a string in another case,
    > 7 floats and an array of UDTs in another case, etc.
    >

    Assuming you have a fixed set of operations, you could look at wrapping
    the base types in a container class with a fixed set of operators and
    working with those.

    > My first thought was to create a class that had a one map for every
    > possible type, but I am not sure that is the best.
    >
    > I was also thinking of making seperate "Material Property" classes
    > that could be added and removed from a "Material", but its fuzzy.
    >

    That sounds a bit like my suggestion, investigate it further.

    --
    Ian Collins
     
    Ian Collins, Oct 10, 2008
    #2
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  3. Christopher <> writes:

    > Is it possible to dynamically create a data structure?


    Yes.


    > Not that it matters, but just for understanding, I am working with
    > video shaders, these shaders use thier own language (HLSL) which you
    > compile at runtime and run for rendering. The HLSL can contain many
    > differant types of variables and expect your application to set them.
    >
    > The library provides the ability to query for
    > number of variables
    > thier names
    > thier types
    > and provides a method for setting them that is depedent on the type


    Then you already have it here. What other data structure do you want,
    beyond what that library provides?


    > My goal is to package them, no matter what they are, into a single
    > material class, that can be used no matter what the HLSL it
    > corresponds to looks like.


    Ok so you want to write some wrapper, to be able to use it abstractly,
    because that library doesn't already provide the abstract layer.


    > So, I want the same data structure that is capable of setting, for
    > example, two floats in one case, a float and a string in another case,
    > 7 floats and an array of UDTs in another case, etc.


    Well, having a single abstract class for the interface doesn't remove
    that it will be simplier to treat each of the case in a different
    concrete subclass, so the implementation of your wrapper won't be a
    single class.

    > My first thought was to create a class that had a one map for every
    > possible type, but I am not sure that is the best.
    >
    > I was also thinking of making seperate "Material Property" classes
    > that could be added and removed from a "Material", but its fuzzy.
    >
    > Any ideas?



    So here is your single abstract data structure capable of setting:

    class Data{
    virtual void setHLSLData(hslshandle*)=0;
    };


    Now you can define subclasses for each of the C++ data types you need
    to set.

    class IntData{
    protected: int value;
    public: IntData(int aValue):value(aValue){};
    public: virtual void setHLSLData(hslshandle* hslsdata){
    if(hslsType(hslsdata)==hslsInteger){
    hslsSetInteger(hslsdata,value);
    }else{
    throw TypeError("Cannot assign an int to a "+hslsTypeName(hslsdata));;
    }
    }
    };

    and so on for the other data types. You can also use templates to
    define a bunch of then.

    If you have structures or vectors, you can easily define a subclass of
    Data with a map of fieldName to Data items, or a vector of Data items,
    etc.

    --
    __Pascal Bourguignon__
     
    Pascal J. Bourguignon, Oct 10, 2008
    #3
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