How to Bulk Import to R-tree using a Generator?

Question

I've been trying to improve one of a couple of scripts I'm writing to be comparable to the other script in performance speed which uses a different approach to tackle the same FGDB problem. I'm simply trying to find buildings within perennial waters.

It's been brought to my attention even though I'm trying to do an R-Tree via a bounding box spatial analysis, that I may doing it wrong by not doing a bulk import to R-Tree via a generator.

Some concerns I have is it seems I need to manually find each feature's minimum bounding rectangle and also utilize a generator manually defined (which I've copied from the R-Tree website).

My code below which is currently getting me nowhere:

def getMBR(feature):

    global maxX
    global minX
    global maxY
    global minY

    for currFeature in feature[1]['coordinates']:
        if currFeature:
            for x,y,z in currFeature:
                if (maxX == maxY):

                    maxX = x
                    minX = x

                    maxY = y
                    minY = y

                else:

                    maxX = max(maxX, x)
                    minX = min(minX, x)

                    maxY = max(maxY, y)
                    minY = min(minY, y)
    return


def generator_function(someData):

    for i, obj in enumerate(someData):
        yield(i, (obj.xmin, obj.ymin, obj.xmax, obj.ymax), obj)
    return


def applyRTree(layer1, layer2):
    with fiona.open(sourceDatabaseFile, 'r', layer=layer2) as sourceFile2:
        for water in sourceFile2:
            if (('ZI024_HYP' in water['properties']) and (water['properties']['ZI024_HYP'] == 1)):
                waterFeatures.append((water['id'], water['geometry'], water['properties']))
        sourceFile2.close()

    #from rtree import index
    w = index.Property()
    idx = index.Index(properties=w)
    for i, coords in enumerate(waterFeatures):
        getMBR(coords)
        idx.add(i,(minX, minY, maxX, maxY)) 
        maxX = maxY = minX = minY = float(0.0)        

    b = index.Property()
    idx2 = index.Index(properties=b)
    for i, coords in enumerate(buildingFeatures):
        getMBR(coords)
        idx2.add(i,(minX, minY, maxX, maxY))
        maxX = maxY = minX = minY = float(0.0)

    hits = idx.intersection(idx2, objects=True)

try: 

        for bldg in buildingLayerList:
            with fiona.open(sourceDatabaseFile, 'r', layer=bldg) as sourceFile1:
                for building in sourceFile1:
                    buildingFeatures.append((building['id'], building['geometry']))
                sourceFile1.close()

            #Use current list of buildings and compare against all hydrography layers
            for hydro in hydrographyLayerList:
                applyRTree(bldg, hydro)