- 参照 URL
- PFM Portable FloatMap Image Format
- Light Probe Image Gallery by Paul Debevec
- 下のようなLight Probe の画像のうち, PFM フォーマットの画像を読み込んで PPM フォーマットに変換する C のコード
- コードは未整理かつ かなり決めうちだけど, メモとして以下に貼り付け
// PFM を読み込む
FILE* p_texture_file = nullptr;
{
const char* pfm_filename = "textures/memorial.pfm";
fopen_s( ( & p_texture_file ), pfm_filename, "rb" );
const bool is_success = ( p_texture_file != nullptr );
MY_ASSERT_MSG( is_success );
}
f32* p_texture_buffer = nullptr;
u32 texture_width = 0;
u32 texture_height = 0;
u32 total_texture_pixel_num = 0;
u32 total_texture_f32_num = 0;
u32 total_texture_byte_size = 0;
{
char type_str[ 128 ];
f32 byte_order;
const u32 c_buffer_size = 256;
char p_buffer[ c_buffer_size ];
u32 line_num = 0;
// ヘッダの読み込み
while ( ( fgets( p_buffer, c_buffer_size, p_texture_file ) != nullptr ) )
{
if ( line_num < 3 )
{
printf( "line %d: %s", line_num, p_buffer );
if ( line_num == 0 )
{
sscanf_s( p_buffer, "%2c", ( &type_str ) );
type_str[ 2 ] = '\0';
}
else if ( line_num == 1 )
{
sscanf_s( p_buffer, "%d %d",
( &texture_width ), ( &texture_height ) );
total_texture_pixel_num = texture_width * texture_height;
total_texture_f32_num = 3 * total_texture_pixel_num;
total_texture_byte_size = sizeof( f32 ) * total_texture_f32_num;
}
else if ( line_num == 2 )
{
sscanf_s( p_buffer, "%f", ( &byte_order ) );
break;
}
}
line_num++;
}
if ( p_texture_buffer == nullptr )
{
p_texture_buffer = new f32[ 3 * total_texture_pixel_num ]();
MY_ASSERT( p_texture_buffer != nullptr );
}
const size_t read_texture_byte_size =
fread( p_texture_buffer, sizeof( f32 ), total_texture_f32_num, p_texture_file );
const bool is_success =
( read_texture_byte_size == total_texture_byte_size );
MY_ASSERT_MSG( ( ! is_success ),
"read_texture_byte_size = %d, assumed_size = %d",
read_texture_byte_size, total_texture_byte_size );
// Write image to PPM file.
{
FILE *f;
fopen_s( ( &f ), "test_pfm.ppm", "w" );
fprintf( f, "P3\n%d %d\n%d\n", texture_width, texture_height, 255 );
for ( u32 y = 0; y < texture_height; ++y )
{
for ( u32 x = 0; x < texture_width; ++x )
{
// PFM : specified in left to right, bottom to top order
// PPM : A raster of Height rows, in order from top to bottom.
// PPM に書き出すために, Y 反転
const u32 read_y = ( texture_height - y - 1 );
const u32 pixel_index = read_y * texture_width + x;
const f32 r = p_texture_buffer[ 3 * pixel_index ];
const f32 g = p_texture_buffer[ 3 * pixel_index + 1 ];
const f32 b = p_texture_buffer[ 3 * pixel_index + 2 ];
fprintf( f, "%d %d %d ", toInt( r ), toInt( g ), toInt( b ) );
}
}
}
printf( "header = %s\n", type_str );
printf( "width = %d, height = %d\n", texture_width, texture_height );
printf( "byte_order = %f\n", byte_order );
printf( "total_texture_pixel_num = %d, total_texture_byte_size = %d\n",
total_texture_pixel_num, total_texture_byte_size );
printf( "Total line_num = %d\n", line_num );
MY_ASSERT( p_texture_buffer != nullptr );
}
- 追記
- このままだと使いにくかったので, 以下は構造体にしたバージョン
- 下は使い方と構造体 PfmTexture
PfmTexture s_PfmTexture;
// ライトプローブテクスチャの読み込み
const char* pfm_filename = "textures/grace_probe.pfm";
s_PfmTexture.create( pfm_filename );
// PPM に変換
s_PfmTexture.writePPM( "test_output.ppm" );
// x = 32, y = 58 ピクセル目のカラーを取得
Vec rgb;
s_PfmTexture.readPixel( ( & rgb ), x, y );struct PfmTexture
{
PfmTexture() :
mpTextureFilename( nullptr ),
mpFile( nullptr ),
mpTextureBuffer( nullptr ),
mTextureWidth( 0 ),
mTextureHeight( 0 ),
mTotalTexturePixelNum( 0 ),
mTotalTextureF32Num( 0 ),
mTotalTextureByteSize( 0 ),
mByteOrder( - 1.0f )
{
}
~PfmTexture()
{
destroy();
}
bool create( const char* filename )
{
{
MY_NULL_ASSERT( filename );
mpTextureFilename = filename;
fopen_s( ( & mpFile ), mpTextureFilename, "rb" );
const bool is_success = ( mpFile != nullptr );
MY_ASSERT_MSG( is_success, "Failed to open %s.\n", mpTextureFilename );
}
char type_str[ 128 ];
const u32 c_buffer_size = 256;
char p_buffer[ c_buffer_size ];
u32 line_num = 0;
// ヘッダの読み込み
while ( ( fgets( p_buffer, c_buffer_size, mpFile ) != nullptr ) )
{
if ( line_num < 3 )
{
printf( "line %d: %s", line_num, p_buffer );
if ( line_num == 0 )
{
sscanf_s( p_buffer, "%2c", ( &type_str ) );
type_str[ 2 ] = '\0';
}
else if ( line_num == 1 )
{
sscanf_s( p_buffer, "%d %d",
( & mTextureWidth ), ( & mTextureHeight ) );
mTotalTexturePixelNum = mTextureWidth * mTextureHeight;
mTotalTextureF32Num = 3 * mTotalTexturePixelNum;
mTotalTextureByteSize = sizeof( f32 ) * mTotalTextureF32Num;
}
else if ( line_num == 2 )
{
sscanf_s( p_buffer, "%f", ( & mByteOrder ) );
break;
}
}
line_num++;
}
if ( mpTextureBuffer == nullptr )
{
mpTextureBuffer = new f32[ mTotalTextureF32Num ]();
MY_ASSERT( mpTextureBuffer != nullptr );
}
// ピクセルデータを一気に読み込む
const size_t read_texture_byte_size =
fread( mpTextureBuffer, sizeof( f32 ),
mTotalTextureF32Num, mpFile );
const bool is_success =
( read_texture_byte_size == mTotalTextureByteSize );
MY_ASSERT_MSG( ( ! is_success ),
"read_texture_byte_size = %d, assumed_size = %d",
read_texture_byte_size, mTotalTextureByteSize );
return true;
}
void destroy()
{
if ( mpFile != nullptr )
{
fclose( mpFile );
mpFile = nullptr;
}
if ( mpTextureBuffer != nullptr )
{
delete[] mpTextureBuffer;
mpTextureBuffer = nullptr;
}
}
void readPixel( Vec* p_rgb, const u32 x, const u32 y, const bool enable_y_flip = false )
{
MY_NULL_ASSERT( p_rgb );
MY_NULL_ASSERT( mpFile );
MY_NULL_ASSERT( mpTextureBuffer );
MY_ASSERT( x < mTextureWidth );
MY_ASSERT( y < mTextureHeight );
const u32 read_y = ( enable_y_flip ? ( mTextureHeight - y - 1 ) : y );
const u32 pixel_index = read_y * mTextureWidth + x;
const u32 array_index = 3 * pixel_index;
( *p_rgb ).x = mpTextureBuffer[ array_index ];
( *p_rgb ).y = mpTextureBuffer[ array_index + 1 ];
( *p_rgb ).z = mpTextureBuffer[ array_index + 2 ];
}
void writePPM( const char* ppm_filename )
{
FILE* f;
fopen_s( ( & f ), ppm_filename, "w" );
fprintf( f, "P3\n%d %d\n%d\n", mTextureWidth, mTextureHeight, 255 );
for ( u32 y = 0; y < mTextureHeight; ++y )
{
for ( u32 x = 0; x < mTextureWidth; ++x )
{
// PFM : specified in left to right, bottom to top order
// PPM : A raster of Height rows, in order from top to bottom.
// PPM に書き出すために, Y 反転
Vec rgb;
readPixel( ( & rgb ), x, y, true );
fprintf( f, "%d %d %d ", toInt( rgb.x ), toInt( rgb.y ), toInt( rgb.z ) );
}
}
fclose( f );
}
const char* mpTextureFilename;
FILE* mpFile;
f32* mpTextureBuffer;
u32 mTextureWidth;
u32 mTextureHeight;
u32 mTotalTexturePixelNum;
u32 mTotalTextureF32Num;
u32 mTotalTextureByteSize;
f32 mByteOrder;
};
