<?php
# StarCraft 2 M3 to OBJ Converter v0.5
#########################
    $temp = explode(".m3", $argv[1]);
    $file = $argv[1];
    $export = $temp[0] . ".obj";
########################    
function uint32($offset){
  global $file;
  fseek($file, $offset);
  $uint32 = unpack(V, fread($file, 4));
  return $uint32[1];
}
function uint16($offset){
  global $file;
  fseek($file, $offset);
  $uint16 = unpack(v, fread($file, 2));
  return $uint16[1];
}
function uint8($offset){
  global $file;
  fseek($file, $offset);
  $uint8 = unpack(C, fread($file, 1));
  return $uint8[1];
}
function float16($offset){
  global $file;
  fseek($file, $offset);
  $float = unpack(f, fread($file, 4));
  return $float[1];
}
    echo("Exporting Model $path to $path.obj\n\n");
    $file = fopen($file, 'rb') or die("Failed to open $file!\n");
    if(fread($file,4) != "33DM") die("Failed! File is not a StarCraft 2 model!\n");
    fseek($file, 4); # find where tags start
    $tags = uint32(4); //start of tags
    $offset = uint32($tags + 20) + 4*16;
    $flags = uint32($offset);
    if (($flags & 1) == 0) {
      $EOB = 4; 
    } else { 
      $EOB = 8; 
    } # bytes to reach end of vertex block after uv
    $vertLength = uint32($offset+8); # length of vertex block
    $index = uint32($offset+12); # vertex tag index
    $offVerts = uint32($index*16 + $tags + 4); # vertex tag
    if ($EOB == 4) {
      $nVerts = $vertLength / 32;
    } else {
      $nVerts = $vertLength / 36;
    }
    $index = uint32($offset+20); # DIV tag index    
    $offDIV = uint32($index*16 + $tags + 4); # DIV tag
    $k = 0;
    for($i=0;$i<$nVerts;$i++){
      for($j=0;$j<3;$j++){ # read verts
        $vert[3*$i+$j] = float16($offVerts);#$read[1];
        $offVerts +=4;
      }
      # bone weights [4]
      # bones [4]
      $offVerts+=8;
      $w = 2*uint8($offVerts+3)/255-1; // need w to convert to cartesian.
      for($j=0;$j<3;$j++){ # read verts
        $normal[3*$i+$j] = (2*uint8($offVerts)/255-1)/$w;
        $offVerts +=1;
      }
      $offVerts++;
      for($j=0;$j<2;$j++){ # read UV
        $raw = uint16($offVerts);# normal
        if ($raw > 2046){
          $uv[$k] = $raw / 65535;
        } else {
          $uv[$k] = $raw / 2048;
        } 
        $offVerts +=2;
        $k++;
      }
      $offVerts+=$EOB;    
    }
    # Read Face # and offset from DIV
    $nFaces = uint32($offDIV) / 3;
    $index = uint32($offDIV+4); # faces tag
    $offFaces = uint32($index*16 + $tags + 4);
    $nRegions = uint32($offDIV+8);
    $index = uint32($offDIV+12); # Regions Tag
    $offRegions = uint32($index*16 + $tags + 4);
    # Build Regions
    for ($i=0;$i<2*$nRegions;$i+=2){      
      $Region[$i] = uint32($offRegions+8) / 3; # offset
      $Region[$i+1] = uint32($offRegions+12) /3; # count
      $offRegions += 28; #16;      
    }
    # Read faces
    for ($i=0;$i<3*$nFaces;$i++){
      $face[$i]= uint16($offFaces);
      $offFaces+=2;
    }
    $out = fopen($export, 'w+');
    for($i=0; $i<sizeof($vert); $i+=3){ # write out verts
      fwrite($out, "v " . $vert[$i] . " " . $vert[$i+1] . " " . $vert[$i+2] . "\n");
    }
    for($i=0; $i<sizeof($normal); $i+=3){ # write out normals
      fwrite($out, "nv " . $normal[$i] . " " . $normal[$i+1] . " " . $normal[$i+2] . "\n");
    }
    for($i=0; $i<sizeof($uv); $i+=2){ # write uv
      fwrite($out, "vt " . $uv[$i] . " " . (1-$uv[$i+1]) . "\n");
    }
    #iterate through Regions
    for($j=0; $j<sizeof($Region);$j+=2){
      $f = $Region[$j]; // # Face index
      fwrite($out, "g Mesh".($j/2)."\nusemtl Mat" . ($j/2) . "\n");
      for($i=0;$i<$Region[$j+1];$i++){
      fwrite($out, "f " . ($face[3*$f]+1) . "/" . ($face[3*$f]+1) . "/" . ($face[3*$f]+1) . " " . ($face[3*$f+1]+1) . "/" . ($face[3*$f+1]+1) . "/". ($face[3*$f+1]+1) . " " . ($face[3*$f+2]+1) . "/" . ($face[3*$f+2]+1) . "/" . ($face[3*$f+2]+1) . "\n");
      $f++;
      }
    }
    fclose($out);
    echo("Done!\n\n");
?>