function cbPreparePptxToGenerate() {
    genobj.generate_data = {}

    // Tell all the features (plugins) that we are about to generate a new document zip:
    gen_private.features.type.pptx.emitEvent('beforeGen', genobj)

    // Allow some plugins to do more stuff after all the plugins added their data:
    gen_private.features.type.pptx.emitEvent('beforeGenFinal', genobj)

    // Apple Keynote requires these added *after* all slides:
    gen_private.type.msoffice.rels_app.push(
      {
        type:
          'http://schemas.openxmlformats.org/officeDocument/2006/relationships/presProps',
        target: 'presProps.xml',
        clear: 'type'
      },
      {
        type:
          'http://schemas.openxmlformats.org/officeDocument/2006/relationships/viewProps',
        target: 'viewProps.xml',
        clear: 'type'
      },
      {
        type:
          'http://schemas.openxmlformats.org/officeDocument/2006/relationships/theme',
        target: 'theme/theme1.xml',
        clear: 'type'
      }
    )

    // This event allow the plugins to add permanent rels that must be at the end:
    var extraMainRelList = []
    gen_private.features.type.pptx.emitEvent('addMainRels', {
      genobj: genobj,
      relsList: extraMainRelList
    })
    extraMainRelList.forEach(function (value) {
      gen_private.type.msoffice.rels_app.push(value)
    })

    // Add any extra rels needed by the plugins and depended on the data:
    if (
      gen_private.type.pptx.extraMainRelList &&
      typeof gen_private.type.pptx.extraMainRelList === 'object' &&
      gen_private.type.pptx.extraMainRelList.forEach
    ) {
      gen_private.type.pptx.extraMainRelList.forEach(function (value) {
        gen_private.type.msoffice.rels_app.push(value)
      })
    }

    gen_private.type.msoffice.rels_app.push({
      type:
        'http://schemas.openxmlformats.org/officeDocument/2006/relationships/tableStyles',
      target: 'tableStyles.xml',
      clear: 'type'
    })
  }
Prepare everything to generate PPTX files.

This method checking for extra resources needed to add by the generator engine.