Mtk's Blog: [Blender] obj2opengl.plをJava用に改造する

Blender object to OpenGL for Android Java

3DCG作成ツール「Blender」のobjファイルをC言語のhファイルに変換するperlスクリプト「obj2opengl.pl」を使ってみました。
obj2opengl: convert obj 3D models to arrays compatible with iPhone OpenGL ES « Heiko Behrens (Blog): http://heikobehrens.net/2009/08/27/obj2opengl/
からHBehrens-obj2opengl-a0f123e.zipをダウンロードしました。

BlenderのデータをAndroidでも使いたいのでobj2opengl.plをobjファイルをjavaファイルに変換するように改造してみました。

改造した内容は次の通りです。
・float型の数値にサフィックスfをつける
・クラス名・変数名が数字で始まる場合は先頭に「_」をつける
・unsigned intをintに変更
・クラス名・ファイル名の最初の文字が小文字なら大文字に変換する
・パッケージのステートメント追加
・FloatBuffer宣言の追加

ソースです。
obj2opengl4java.pl

#! /usr/bin/perl
=head1 NAME

 obj2opengl4java - converts obj files to arrays for gl.glDrawArrays

=head1 SYNOPSIS

 obj2opengl4java [options] file

=cut

use Getopt::Long;
use File::Basename;
use Pod::Usage;

# -----------------------------------------------------------------
# Main Program
# -----------------------------------------------------------------
handleArguments();

# derive center coords and scale factor if neither provided nor disabled
unless(defined($scalefac) && defined($xcen)) {
 calcSizeAndCenter();
}

if($verbose) {
 printInputAndOptions();
}

# TODO check integrity: Does every referenced vertex, normal and coord exist?
loadData();
normalizeNormals();

if($verbose) {
 printStatistics();
}

writeOutput();

# -----------------------------------------------------------------
# Sub Routines
# -----------------------------------------------------------------

sub handleArguments() {
 my $help = 0;
 my $man = 0;
 my $noscale = 0;
 my $nomove = 0;
 $verbose = 1;
 $errorInOptions = !GetOptions (
  "help" => \$help,
  "man"  => \$man,
  "noScale" => \$noscale,
  "scale=f" => \$scalefac,
  "noMove" => \$nomove,
  "center=f{3}" => \@center,
  "outputFilename=s" => \$outFilename,
  "nameOfObject=s" => \$object,
  "verbose!" => \$verbose,
  );
 
 if($noscale) {
  $scalefac = 1;
 }
 
 if($nomove) {
  @center = (0, 0, 0);
 }
 
 if(defined(@center)) {
  $xcen = $center[0];
  $ycen = $center[1];
  $zcen = $center[2];
 }
 
 if($#ARGV == 0) {
  my ($file, $dir, $ext) = fileparse($ARGV[0], qr/\.[^.]*/);
  $inFilename = $dir . $file . $ext;
 } else {
  $errorInOptions = true;
 }

 # (optional) derive output filename from input filename
 unless($errorInOptions || defined($outFilename)) {
  my ($file, $dir, $ext) = fileparse($inFilename, qr/\.[^.]*/);
  $object = $file;
  $classname = $file;
  $classname =~ s/(^\w)/\u$1/;
  $classname =~ s/(^\d)/_$1/;
  $outFilename = $dir . $classname . ".java";
 }
 
 # (optional) define object name from output filename
 unless($errorInOptions || defined($object)) {
  my ($file, $dir, $ext) = fileparse($outFilename, qr/\.[^.]*/);
  $object = $file;
 }
 
 ($inFilename ne $outFilename) or
  die ("Input filename must not be the same as output filename")
  unless($errorInOptions);
  
 if($errorInOptions || $man || $help) {
  pod2usage(-verbose => 2) if $man;
  pod2usage(-verbose => 1) if $help;
  pod2usage(); 
 }
 
 # check wheter file exists
 open ( INFILE, "<$inFilename" ) 
   || die "Can't find file '$inFilename' ...exiting \n";
 close(INFILE);
}

# Stores center of object in $xcen, $ycen, $zcen
# and calculates scaling factor $scalefac to limit max
#   side of object to 1.0 units
sub calcSizeAndCenter() {
 open ( INFILE, "<$inFilename" ) 
   || die "Can't find file $inFilename...exiting \n";

 $numVerts = 0;
 
 my (
  $xsum, $ysum, $zsum, 
  $xmin, $ymin, $zmin,
  $xmax, $ymax, $zmax,
  );

 while ( $line = <INFILE> ) {
   chop $line;
   
   if ($line =~ /v\s+.*/) {
   
     $numVerts++;
     @tokens = split(' ', $line);
     
     $xsum += $tokens[1];
     $ysum += $tokens[2];
     $zsum += $tokens[3];
     
     if ( $numVerts == 1 ) {
       $xmin = $tokens[1];
       $xmax = $tokens[1];
       $ymin = $tokens[2];
       $ymax = $tokens[2];
       $zmin = $tokens[3];
       $zmax = $tokens[3];
     } else {   
         if ($tokens[1] < $xmin) {
         $xmin = $tokens[1];
       } elsif ($tokens[1] > $xmax) {
         $xmax = $tokens[1];
       }
     
       if ($tokens[2] < $ymin) {
         $ymin = $tokens[2];
       } elsif ($tokens[2] > $ymax) {
         $ymax = $tokens[2];
       }
     
       if ($tokens[3] < $zmin) {
         $zmin = $tokens[3];
       } elsif ($tokens[3] > $zmax) {
         $zmax = $tokens[3];
       }
     
     }
  
   }
  
 }
 close INFILE;
 
 #  Calculate the center
 unless(defined($xcen)) {
  $xcen = $xsum / $numVerts;
  $ycen = $ysum / $numVerts;
  $zcen = $zsum / $numVerts;
 }
 
 #  Calculate the scale factor
 unless(defined($scalefac)) {
  my $xdiff = ($xmax - $xmin);
  my $ydiff = ($ymax - $ymin);
  my $zdiff = ($zmax - $zmin);
  
  if ( ( $xdiff >= $ydiff ) && ( $xdiff >= $zdiff ) ) {
    $scalefac = $xdiff;
  } elsif ( ( $ydiff >= $xdiff ) && ( $ydiff >= $zdiff ) )  {
    $scalefac = $ydiff;
  } else {
    $scalefac = $zdiff;
  }
  $scalefac = 1.0 / $scalefac;
 }
}

sub printInputAndOptions() {
 print "Input file     : $inFilename\n";
 print "Output file    : $outFilename\n";
 print "Object name    : $object\n";
 print "Center         : <$xcen, $ycen, $zcen>\n";
 print "Scale by       : $scalefac\n";
}

sub printStatistics() {
 print "----------------\n";
 print "Vertices       : $numVerts\n";
 print "Faces          : $numFaces\n";
 print "Texture Coords : $numTexture\n";
 print "Normals        : $numNormals\n";
}

# reads vertices into $xcoords[], $ycoords[], $zcoords[]
#   where coordinates are moved and scaled according to
#   $xcen, $ycen, $zcen and $scalefac
# reads texture coords into $tx[], $ty[] 
#   where y coordinate is mirrowed
# reads normals into $nx[], $ny[], $nz[]
#   but does not normalize, see normalizeNormals()
# reads faces and establishes lookup data where
#   va_idx[], vb_idx[], vc_idx[] for vertices
#   ta_idx[], tb_idx[], tc_idx[] for texture coords
#   na_idx[], nb_idx[], nc_idx[] for normals
#   store indizes for the former arrays respectively
#   also, $face_line[] store actual face string
sub loadData {
 $numVerts = 0;
 $numFaces = 0;
 $numTexture = 0;
 $numNormals = 0;
 
 open ( INFILE, "<$inFilename" )
   || die "Can't find file $inFilename...exiting \n";
 
 while ($line = <INFILE>) {
   chop $line;
   
   # vertices
   if ($line =~ /v\s+.*/) {
     @tokens= split(' ', $line);
     $x = ( $tokens[1] - $xcen ) * $scalefac;
     $y = ( $tokens[2] - $ycen ) * $scalefac;
     $z = ( $tokens[3] - $zcen ) * $scalefac;
     $xcoords[$numVerts] = $x; 
     $ycoords[$numVerts] = $y;
     $zcoords[$numVerts] = $z;
 
     $numVerts++;
   }
   
   # texture coords
   if ($line =~ /vt\s+.*/) {
     @tokens= split(' ', $line);
     $x = $tokens[1];
     $y = 1 - $tokens[2];
     $tx[$numTexture] = $x;
     $ty[$numTexture] = $y;
     
     $numTexture++;
   }
   
   #normals
   if ($line =~ /vn\s+.*/) {
     @tokens= split(' ', $line);
     $x = $tokens[1];
     $y = $tokens[2];
     $z = $tokens[3];
     $nx[$numNormals] = $x; 
     $ny[$numNormals] = $y;
     $nz[$numNormals] = $z;
 
     $numNormals++;
   }
   
   # faces
   if ($line =~ /f\s+([^ ]+)\s+([^ ]+)\s+([^ ]+)/) {
    @a = split('/', $1);
    @b = split('/', $2);
    @c = split('/', $3);
    $va_idx[$numFaces] = $a[0]-1;
    $ta_idx[$numFaces] = $a[1]-1;
    $na_idx[$numFaces] = $a[2]-1;
 
    $vb_idx[$numFaces] = $b[0]-1;
    $tb_idx[$numFaces] = $b[1]-1;
    $nb_idx[$numFaces] = $b[2]-1;
 
    $vc_idx[$numFaces] = $c[0]-1;
    $tc_idx[$numFaces] = $c[1]-1;
    $nc_idx[$numFaces] = $c[2]-1;
    
    $face_line[$numFaces] = $line;
    
  $numFaces++;
   }
 }
 
 close INFILE;
}

sub normalizeNormals {
 for ( $j = 0; $j < $numNormals; ++$j) {
  $d = sqrt ( $nx[$j]*$nx[$j] + $ny[$j]*$ny[$j] + $nz[$j]*$nz[$j] );
   
   if ( $d == 0 ) {
     $nx[$j] = 1;
     $ny[$j] = 0;
     $nz[$j] = 0;
   } else {
     $nx[$j] = $nx[$j] / $d;
     $ny[$j] = $ny[$j] / $d;
     $nz[$j] = $nz[$j] / $d;
   }
 }
}

sub writeOutput {
 open ( OUTFILE, ">$outFilename" ) 
   || die "Can't create file $outFilename ... exiting\n";
 
 print OUTFILE "/*\n";
 print OUTFILE "created with obj2opengl4java.pl\n\n";

 # some statistics
 print OUTFILE "source file    : $inFilename\n";
 print OUTFILE "vertices       : $numVerts\n";
 print OUTFILE "faces          : $numFaces\n";
 print OUTFILE "normals        : $numNormals\n";
 print OUTFILE "texture coords : $numTexture\n";
 print OUTFILE "\n\n";
 
 # example usage
 print OUTFILE "// make FloatBuffer and\n";
 print OUTFILE "// set input data to arrays\n";
 print OUTFILE "gl.glVertexPointer(3, GL10.GL_FLOAT, 0, ".$object."VertBuffer);\n";
 print OUTFILE "gl.glNormalPointer(GL10.GL_FLOAT, 0, ".$object."NormalBuffer);\n"
  if $numNormals > 0;
 print OUTFILE "gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, ".$object."TexCoordBuffer);\n"
  if $numTexture > 0;
 print OUTFILE "\n";
 print OUTFILE "// draw data\n";
 print OUTFILE "gl.glDrawArrays(GL10.GL_TRIANGLES, 0, ".$object."NumVerts);\n";
 print OUTFILE "*/\n\n";
 
 print OUTFILE "//FIXME\n";
 print OUTFILE "package jp.fujiu.obj2opengl4java;\n\n";
 print OUTFILE "import java.nio.FloatBuffer;\n\n";
 print OUTFILE "public class $classname {\n\n";

 # needed constant for glDrawArrays
 print OUTFILE "\tint ".$object."NumVerts = ".($numFaces * 3).";\n\n";
 
 # write verts
 print OUTFILE "\tfloat ".$object."Verts \[\] = {\n"; 
 for( $j = 0; $j < $numFaces; $j++) {
  $ia = $va_idx[$j];
  $ib = $vb_idx[$j];
  $ic = $vc_idx[$j];
  print OUTFILE "\t\t// $face_line[$j]\n";
  print OUTFILE "\t\t$xcoords[$ia]f, $ycoords[$ia]f, $zcoords[$ia]f,\n";
  print OUTFILE "\t\t$xcoords[$ib]f, $ycoords[$ib]f, $zcoords[$ib]f,\n";
  print OUTFILE "\t\t$xcoords[$ic]f, $ycoords[$ic]f, $zcoords[$ic]f,\n";
 }
 print OUTFILE "\t};\n\n";
 print OUTFILE "\tFloatBuffer ".$object."VertBuffer;\n\n";
 
 # write normals
 if($numNormals > 0) {
  print OUTFILE "\tfloat ".$object."Normals \[\] = {\n"; 
  for( $j = 0; $j < $numFaces; $j++) {
   $ia = $na_idx[$j];
   $ib = $nb_idx[$j];
   $ic = $nc_idx[$j];
   print OUTFILE "\t\t// $face_line[$j]\n";
   print OUTFILE "\t\t$nx[$ia]f, $ny[$ia]f, $nz[$ia]f,\n";
   print OUTFILE "\t\t$nx[$ib]f, $ny[$ib]f, $nz[$ib]f,\n";
   print OUTFILE "\t\t$nx[$ic]f, $ny[$ic]f, $nz[$ic]f,\n";
  }
  
  print OUTFILE "\t};\n\n";
  print OUTFILE "\tFloatBuffer ".$object."NormalBuffer;\n\n";
 }
 
 # write texture coords
 if($numTexture) {
  print OUTFILE "\tfloat ".$object."TexCoords \[\] = {\n"; 
  for( $j = 0; $j < $numFaces; $j++) {
   $ia = $ta_idx[$j];
   $ib = $tb_idx[$j];
   $ic = $tc_idx[$j];
   print OUTFILE "\t\t// $face_line[$j]\n";
   print OUTFILE "\t\t$tx[$ia]f, $ty[$ia]f,\n";
   print OUTFILE "\t\t$tx[$ib]f, $ty[$ib]f,\n";
   print OUTFILE "\t\t$tx[$ic]f, $ty[$ic]f,\n";
  }
  
  print OUTFILE "\t};\n\n";
  print OUTFILE "\tFloatBuffer ".$object."TexCoordBuffer;\n\n";
 }
 
 print OUTFILE "}\n";
 
 close OUTFILE;
}

obj2opengl4java.pl の使い方
obj2opengl4java.plはコマンドプロンプト(コンソール)で操作します。
変換したいオブジェクトファイルはHBehrens-obj2opengl-a0f123e.zipに含まれているcube.objとします。
obj2opengl4java.plとオブジェクトファイル(cube.obj)を同じフォルダーに保存します。
カレントフォルダーはファイルを保存したフォルダーとします。

WindowsならActivePerlなどをインストールしperl.exeのPath設定してコマンドプロンプトから
perl obj2opengl4java.pl cube.obj
と入力します。

CygwinやLinuxなら
./obj2opengl4java.pl cube.obj
と入力します。

成功するとCube.javaが作られます。
Cube.javaをAndroidプロジェクトにインポートし、パッケージ名を適切に修正してください。
Cube.java（コメント行は省略）

package jp.fujiu.AndroidApp.BlenderTest;
import java.nio.FloatBuffer;

public class Cube {
 int cubeNumVerts = 36;
 float cubeVerts [] = {
  // f 5 1 4
  0.499999812500094f, 0.499999750000125f, -0.499999812500094f,
  0.499999812500094f, -0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, -0.499999750000125f, -0.499999812500094f,
  // f 5 4 8
  0.499999812500094f, 0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, -0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, 0.499999750000125f, -0.499999812500094f,
  // f 3 7 8
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, 0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, 0.499999750000125f, -0.499999812500094f,
  // f 3 8 4
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, 0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, -0.499999750000125f, -0.499999812500094f,
  // f 2 6 3
  0.499999812500094f, -0.499999750000125f, 0.499999687500156f,
  0.499999312500344f, 0.499999750000125f, 0.500000187499906f,
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  // f 6 7 3
  0.499999312500344f, 0.499999750000125f, 0.500000187499906f,
  -0.499999687500156f, 0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  // f 1 5 2
  0.499999812500094f, -0.499999750000125f, -0.499999812500094f,
  0.499999812500094f, 0.499999750000125f, -0.499999812500094f,
  0.499999812500094f, -0.499999750000125f, 0.499999687500156f,
  // f 5 6 2
  0.499999812500094f, 0.499999750000125f, -0.499999812500094f,
  0.499999312500344f, 0.499999750000125f, 0.500000187499906f,
  0.499999812500094f, -0.499999750000125f, 0.499999687500156f,
  // f 5 8 6
  0.499999812500094f, 0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, 0.499999750000125f, -0.499999812500094f,
  0.499999312500344f, 0.499999750000125f, 0.500000187499906f,
  // f 8 7 6
  -0.499999687500156f, 0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, 0.499999750000125f, 0.499999687500156f,
  0.499999312500344f, 0.499999750000125f, 0.500000187499906f,
  // f 1 2 3
  0.499999812500094f, -0.499999750000125f, -0.499999812500094f,
  0.499999812500094f, -0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  // f 1 3 4
  0.499999812500094f, -0.499999750000125f, -0.499999812500094f,
  -0.499999687500156f, -0.499999750000125f, 0.499999687500156f,
  -0.499999687500156f, -0.499999750000125f, -0.499999812500094f,
 };
 FloatBuffer cubeVertBuffer;
}

Activityのソースです。
Main.java

package jp.fujiu.AndroidApp.BlenderTest;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.app.Activity;
import android.content.Context;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;
import android.opengl.GLSurfaceView.Renderer;
import android.os.Bundle;
import android.view.Window;

public class Main extends Activity {
 private MainSurface surface = null;
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
  //タイトルを非表示
  requestWindowFeature(Window.FEATURE_NO_TITLE);
    }
    
 @Override
 protected void onResume() {
  super.onResume();
  surface = new MainSurface(getApplicationContext());
  surface.setRenderer( surface );
  surface.setFocusable(true);
  setContentView(surface);
 }

 @Override
 protected void onPause() {
  super.onPause();
  surface.onPause();
 }

    
 private class MainSurface extends GLSurfaceView implements Renderer{
  private Cube cube = null;
  
  private float xrot = 0.0f;
  private float yrot = 0.0f;

  //光源パラメーター
  private float[] lightAmbient=new float[]{0.3f,0.3f,0.3f,1.0f};
  private float[] lightDiffuse=new float[]{0.6f,0.6f,0.6f,1.0f};
  private float[] lightPos    =new float[]{0,0,3,1};
  private float[] matAmbient=new float[]{1f,1f,1f,1.0f};
  private float[] matDiffuse=new float[]{1f,1f,1f,1.0f};
  
  public MainSurface(Context context) {
   super(context);
  }

  @Override
  public void onSurfaceCreated(GL10 gl, EGLConfig config) {
   cube = new Cube();
   cube.cubeVertBuffer = makeFloatBuffer(cube.cubeVerts);
   
   //光源の指定
   gl.glEnable(GL10.GL_LIGHTING);
   gl.glEnable(GL10.GL_LIGHT0);
   gl.glMaterialfv(GL10.GL_FRONT_AND_BACK,GL10.GL_AMBIENT,matAmbient,0);
   gl.glMaterialfv(GL10.GL_FRONT_AND_BACK,GL10.GL_DIFFUSE,matDiffuse,0);
   gl.glLightfv(GL10.GL_LIGHT0,GL10.GL_AMBIENT,lightAmbient,0);
   gl.glLightfv(GL10.GL_LIGHT0,GL10.GL_DIFFUSE,lightDiffuse,0);
   gl.glLightfv(GL10.GL_LIGHT0,GL10.GL_POSITION,lightPos,0);
   
   //背景の初期化
   gl.glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
   gl.glClearDepthf(1.0f);
   
   
   //深度テスト
   gl.glEnable(GL10.GL_DEPTH_TEST);
  }

  @Override
  public void onSurfaceChanged(GL10 gl, int width, int height) {
   //射影変換
   gl.glMatrixMode(GL10.GL_PROJECTION);
   gl.glLoadIdentity();
   gl.glViewport(0, 0, width, height);
   GLU.gluPerspective(gl, 45.0f, (float)width/(float)height, 0.1f, 100f);
   
   //モデルビュー変換
   gl.glMatrixMode(GL10.GL_MODELVIEW);
   gl.glLoadIdentity();
   GLU.gluLookAt(gl, 0.0f, 0.0f, 3.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);
  }
  
  @Override
  public void onDrawFrame(GL10 gl) {
   //背景塗り潰し
   gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);
   
   //頂点配列の指定
   gl.glVertexPointer(3, GL10.GL_FLOAT, 0, cube.cubeVertBuffer);
   gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
   
   gl.glPushMatrix();
   
   //回転の指定
   gl.glRotatef(xrot, 1.0f, 0.0f, 0.0f);
   gl.glRotatef(yrot, 0.0f, 1.0f, 0.0f);
   
   gl.glDrawArrays(GL10.GL_TRIANGLES, 0, cube.cubeNumVerts);
   
   gl.glPopMatrix();
   
   xrot += 1f;
   yrot += 2f;
  }
 }
 
 protected static FloatBuffer makeFloatBuffer(float[] arr) {
  ByteBuffer bb = ByteBuffer.allocateDirect(arr.length*4);
  bb.order(ByteOrder.nativeOrder());
  FloatBuffer fb = bb.asFloatBuffer();
  fb.put(arr);
  fb.position(0);
  return fb;
 }
}

このソースを実行するとこうなります。

Blenderで作った球体を回転させるサンプルも作ったらこんな感じになりました。（ソースは省略）

※ただの円に見えますが球です。

Javaにまつわる難点
BlenderのオブジェクトファイルをJavaソースに変換する上で大きな問題があります。
Javaの仕様により定数プールは65536エントリー以内と決められています。
コンストラクターやメソッドは65536バイト以内でなければいけません。
たとえばHBehrens-obj2opengl-a0f123e.zipに含まれるbanana.objは頂点の多いのでJavaソースに変換してもビルドできません。