Add blendparse.py

blendparse.py

@@ -0,0 +1,46 @@
+# A purpose-built class to parse certain information from .blend files.
+
+import io
+
+# A class for opening and reading data from .blend files
+class Blendfile():
+    def __init__(self, filename):
+        self.filename = filename
+        with open(filename, "rb") as f:
+            self.stream = io.BufferedReader(f)
+            self.stream.seek(0)
+
+            # File identifier, 8-byte string; should always be "BLENDER"
+            self.identifier = self.stream.read(7).decode("utf-8")
+
+            # Pointer size, 1-byte char; '-' indicates 8 bytes, '_' indicates 4
+            self.pointer_size = 8 if self.stream.read(1).decode("utf-8") == "-" else 4
+
+            # Endianness, 1-byte char; 'v' indicates little endian, 'V' indicates big
+            self.endianness = "little" if self.stream.read(1).decode("utf-8") == "v" else "big"
+
+            # Blender version, 3-byte int; v2.93 is represented as 293, and so on
+            self.version = int(self.stream.read(3))
+
+            # Looping through file block headers to find scene header
+            # TODO: Implement proper error handling if the target file block does not exist.
+            while True:
+
+                # File block code; identifies type of data
+                code = self.stream.read(4).decode("utf-8")
+
+                # Size of file block, after this header
+                size = int.from_bytes(self.stream.read(4), self.endianness)
+
+                # Seeking to end of file block header
+                self.stream.seek(8+self.pointer_size+size, 1)
+
+                # Scene file block codes will always begin with "SC"
+                if code.startswith("SC"):
+                    # TODO: Acquire SDNA index of scene data, to be found in DNA1 file block
+                    # SDNA index occurs directly following file block size in header
+                    # and is pointer_size bytes long
+                    break
+                
+                # Seeking to the start of the next file block
+                self.stream.seek(8+self.pointer_size+size, 1)