Surface Merger

surface_merging.py

#import timeit


class Surface(object):
    
    """
    The surface class, which contains material information, how many 
    indices it uses, and its starting offset in the index buffer.
    """
    
    def __init__(self, material, icount, start):
        self.material = material
        self.icount = icount
        self.start = start


def merge():
    # A sample index buffer.
    indices = [0, 1, 3, 1, 2, 0, 2, 3, 0, 1, 2, 3]
    
    # Create three surfaces to perform merging on.
    # Surfaces 1 & 3 both use material 1, and thus
    # their indices should be aligned together in
    # the final buffer.
    # Surface 2 uses material 2, so its indices 
    # should follow 1 & 3's.
    
    # Material 1, a Triangle (3 indices), beginning at index 0
    s1 = Surface(1, 3, 0)
    # 6 indices = a quad (I dunno why)
    s2 = Surface(2, 6, 3)
    s3 = Surface(1, 3, 9)

    # All of the surfaces to process
    surfaces = [s1, s2, s3]
    
    # Sort the surfaces by material
    surfaces.sort(key=lambda s: s.material)
    
    # Re-arrange the index buffer in the same way that we did the surfaces
    aligned = []
    for surf in surfaces:
        aligned += indices[surf.start:surf.start + surf.icount]
    
    # Original index
    print "Unaligned indices: ", repr(indices)

    # Aligned index
    print "Aligned indices:   ", repr(aligned)

if __name__ == '__main__':
    merge()
    #print timeit.timeit(merge)
    # 7.91372203827