Post-Effect XML Parser

This week I did some enhancements in  PostEffectLayersParser. An effect can be described by the following structure:

<posteffect>
    <layer name="name" shader="/shader.xml" downsample="0" mipmap="false" maxmipmap="-1">
        <input layer="" texname="tex diffuse" texcoord="texture coordinate 0" pixelsize="pixel size" />
         (...)
        <input source="/tex.png" texname="a texture" />


        <output name="out1" format="argb16_f" reusable="true">
        (...)
        <output ... />
        <parameter name="param_name" type="vector2">1,1<parameter />
        (...)
        <parameter (...)>(...)<parameter />
    </layer>
    <layer>
        (...)
    </layer>
</posteffect>

Based on that structure we have:
An effect can have multiple layers and each layer must specify at least its name and the shader used. Optionally can be specified its downsample, mipmap and maxmipmap.
Each layer can have one or more inputs and one or more outputs.
In the input attributes we have:

• layer - specifies which layer output will be used as input. If omitted will be used the first output of the previous layer (in case it's the first layer then will be used the input texture). The input format is <layername>.<outputname>, if <outputname> is omitted then is used the first output of <layername>.
• texname - shader variable name used to access this texture, if omitted the default value is "tex diffuse"
• texcoord - shader variable name used to access the texture coordinate, if omitted the default value is "texture coordinate 0"
• pixelsize - shader variable name used to access the pixel size for this texture, if omitted no shader variable is provided to the shader.
• source - specifies the path to the texture used as input.

Notice that layer and source are mutual exclusive, and if both attributes are provided layer takes precedence over source. If no input tag is provided then is used one with all default values.

In the output tag can be specified:

• name - the output name, used to access this output as input for other layers, if omitted this output will not be accessible unless this is the first output.
• format -the output texture format, if omitted the default value is "argb8".
• reusable - if false prevents the reuse of this output , if omitted the default value is "true".
• mipmap - enables mipmap generation, overrides the value specified in layer tag, optional.
• maxmipmap - max mipmap level to generate, overrides the value specified in layer tag, optional.

If output tag is omitted, the output used will use all default values.

The parameter tag is used to provide default shader variable values for the post effect.