reference/texreader.py

   1 #!/usr/bin/python
   2 import re
   3 import string
   4 from OpenGL.GL import *
   5
   6 TOKEN_RE = re.compile("[^" + string.whitespace + "]+")
   7 WS_RE = re.compile("[" + string.whitespace + "]+")
   8
   9
  10 class TexReaderException(Exception):
  11         pass
  12
  13
  14 class Texture(object):
  15
  16         def __init__(self, width, height, pixels=None):
  17                 self.textureID = glGenTextures(1)
  18                 self.width = width
  19                 self.height = height
  20
  21                 glBindTexture(GL_TEXTURE_2D, self.textureID)
  22
  23                 # We assume the GL implementation can handle non-power-of-two textures,
  24                 # so we use the image dimensions directly as texture dimensions.
  25                 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height,
  26                                 0, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8_REV, pixels)
  27
  28                 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER)
  29                 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER)
  30
  31         def __del__(self):
  32                 glDeleteTextures([self.textureID])
  33
  34
  35 def parse_ppm(data):
  36         """
  37         Parse the PPM data from the given byte string.
  38         """
  39         try:
  40                 magic, widthStr, heightStr, sampleMaxStr, pixelData = \
  41                                 data.split(None, 4)
  42         except ValueError:
  43                 raise TexReaderException("Can't parse data: %r..." % (data[:40],))
  44
  45         if magic != "P6":
  46                 raise TexReaderException("Unrecognised magic %r" % (magic,))
  47
  48         try:
  49                 width = int(widthStr)
  50                 height = int(heightStr)
  51                 sampleMax = int(sampleMaxStr)
  52         except ValueError, e:
  53                 raise TexReaderException("Can't parse data: %s" % (str(e),))
  54
  55         if sampleMax != 255:
  56                 raise TexReaderException("Textures must have 8 bits per channel.")
  57
  58         if len(pixelData) != (width * height * 3):
  59                 raise TexReaderException("Got %d bytes of pixel data, expected %d"
  60                                 % (len(pixelData), width * height * 3))
  61
  62         # Now to convert this packed RGB pixel data to RGBA data that OpenGL can
  63         # understand.
  64         pixels = []
  65         for pxOffset in range(0, (width * height * 3), 3):
  66                 pixels.append(pixelData[pxOffset:pxOffset+3])
  67                 pixels.append("\xff")
  68
  69         return (width, height, "".join(pixels))
  70
  71
  72 def textureFromFile(filename):
  73         with open(filename, "rb") as handle:
  74                 width, height, pixels = parse_ppm(handle.read())
  75
  76         return Texture(width, height, pixels)
  77
  78
  79 if __name__ == "__main__":
  80         import sys
  81         with open(sys.argv[1]) as handle:
  82                 data = handle.read()
  83                 print parse_ppm(data)