blender-archive/source/blender/imbuf/intern/openexr/openexr_api.cpp

/**
*
 * ***** BEGIN GPLLICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version. 
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Copyright by Gernot Ziegler <gz@lysator.liu.se>.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Austin Benesh, Ton Roosendaal (float, half, speedup, cleanup...).
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <stdlib.h>
#include <stdio.h>
#include <string>


#include <openexr_api.h>

extern "C"
{

// The following prevents a linking error in debug mode for MSVC using the libs in CVS
#if defined(WITH_OPENEXR) && defined(_WIN32) && defined(_DEBUG) && !defined(__MINGW32__) && !defined(__CYGWIN__)
_CRTIMP void __cdecl _invalid_parameter_noinfo(void)
{
}
#endif

#include "MEM_guardedalloc.h"

#include "BLI_blenlib.h"

#include "IMB_imbuf_types.h"
#include "IMB_imbuf.h"
#include "IMB_allocimbuf.h"

#define WITH_OPENEXR
#include "openexr_multi.h"
}

#include <iostream>

#if defined (_WIN32) && !defined(FREE_WINDOWS)
#include <half.h>
#include <IlmImf/ImfVersion.h>
#include <IlmImf/ImfArray.h>
#include <IlmImf/ImfIO.h>
#include <IlmImf/ImfChannelList.h>
#include <IlmImf/ImfPixelType.h>
#include <IlmImf/ImfInputFile.h>
#include <IlmImf/ImfOutputFile.h>
#include <IlmImf/ImfCompression.h>
#include <IlmImf/ImfCompressionAttribute.h>
#include <IlmImf/ImfStringAttribute.h>
#include <Imath/ImathBox.h>
#else
#include <OpenEXR/half.h>
#include <OpenEXR/ImfVersion.h>
#include <OpenEXR/ImathBox.h>
#include <OpenEXR/ImfArray.h>
#include <OpenEXR/ImfIO.h>
#include <OpenEXR/ImfChannelList.h>
#include <OpenEXR/ImfPixelType.h>
#include <OpenEXR/ImfInputFile.h>
#include <OpenEXR/ImfOutputFile.h>
#include <OpenEXR/ImfCompression.h>
#include <OpenEXR/ImfCompressionAttribute.h>
#include <OpenEXR/ImfStringAttribute.h>
#endif

using namespace Imf;
using namespace Imath;

class Mem_IStream: public IStream
{
public:
	
	Mem_IStream (unsigned char *exrbuf, int exrsize):
    IStream("dummy"), _exrpos (0), _exrsize(exrsize)  { _exrbuf = exrbuf; }
	
	virtual bool	read (char c[], int n);
	virtual Int64	tellg ();
	virtual void	seekg (Int64 pos);
	virtual void	clear ();
	//virtual ~Mem_IStream() {}; // unused
	
private:
		
		Int64 _exrpos;
	Int64 _exrsize;
	unsigned char *_exrbuf;
};

bool Mem_IStream::read (char c[], int n)
{
	if (n + _exrpos <= _exrsize)
    {
		memcpy(c, (void *)(&_exrbuf[_exrpos]), n);
		_exrpos += n;
		return true;
    }
	else
		return false;
}

Int64 Mem_IStream::tellg ()
{
	return _exrpos;
}

void Mem_IStream::seekg (Int64 pos)
{
	_exrpos = pos;
}

void Mem_IStream::clear () 
{ 
}

struct _RGBAZ
{
	half r;
	half g;
	half b;
	half a;
	half z;
};

typedef struct _RGBAZ RGBAZ;

extern "C"
{
	
int imb_is_a_openexr(unsigned char *mem)
{
	return Imf::isImfMagic ((const char *)mem);
}

static void openexr_header_compression(Header *header, int compression)
{
	switch(compression)
	{
		case 0:
			header->compression() = NO_COMPRESSION;
			break;
		case 1:
			header->compression() = PXR24_COMPRESSION;
			break;
		case 2:
			header->compression() = ZIP_COMPRESSION;
			break;
		case 3:
			header->compression() = PIZ_COMPRESSION;
			break;
		case 4:
			header->compression() = RLE_COMPRESSION;
			break;
		default:
			header->compression() = ZIP_COMPRESSION;
			break; 
	}
}

static short imb_save_openexr_half(struct ImBuf *ibuf, char *name, int flags)
{
	int channels = ibuf->channels;
	int width = ibuf->x;
	int height = ibuf->y;
	int write_zbuf = (flags & IB_zbuffloat) && ibuf->zbuf_float != NULL;   // summarize
	
	try
	{
		Header header (width, height);
		
		openexr_header_compression(&header, ibuf->ftype & OPENEXR_COMPRESS);
		
		header.channels().insert ("R", Channel (HALF));
		header.channels().insert ("G", Channel (HALF));
		header.channels().insert ("B", Channel (HALF));
		if (ibuf->depth==32 && channels >= 4)
			header.channels().insert ("A", Channel (HALF));
		if (write_zbuf)		// z we do as float always
			header.channels().insert ("Z", Channel (FLOAT));
		
		FrameBuffer frameBuffer;			
		OutputFile *file = new OutputFile(name, header);			
		
		/* we store first everything in half array */
		RGBAZ *pixels = new RGBAZ[height * width];
		RGBAZ *to = pixels;
		int xstride= sizeof (RGBAZ);
		int ystride= xstride*width;

		/* indicate used buffers */
		frameBuffer.insert ("R", Slice (HALF,  (char *) &pixels[0].r, xstride, ystride));	
		frameBuffer.insert ("G", Slice (HALF,  (char *) &pixels[0].g, xstride, ystride));
		frameBuffer.insert ("B", Slice (HALF,  (char *) &pixels[0].b, xstride, ystride));
		if (ibuf->depth==32 && channels >= 4)
			frameBuffer.insert ("A", Slice (HALF, (char *) &pixels[0].a, xstride, ystride));
		if (write_zbuf)
			frameBuffer.insert ("Z", Slice (FLOAT, (char *)(ibuf->zbuf_float + (height-1)*width),
											sizeof(float), sizeof(float) * -width));
		if(ibuf->rect_float) {
			float *from;
			
			for (int i = ibuf->y-1; i >= 0; i--) 
			{
				from= ibuf->rect_float + channels*i*width;
				
				for (int j = ibuf->x; j > 0; j--) 
				{
					to->r = from[0];
					to->g = (channels >= 2)? from[1]: from[0];
					to->b = (channels >= 3)? from[2]: from[0];
					to->a = (channels >= 4)? from[3]: from[0];
					to++; from += 4;
				}
			}
		}
		else {
			unsigned char *from;
			
			for (int i = ibuf->y-1; i >= 0; i--) 
			{
				from= (unsigned char *)ibuf->rect + channels*i*width;
				
				for (int j = ibuf->x; j > 0; j--) 
				{
					to->r = (float)(from[0])/255.0;
					to->g = (float)((channels >= 2)? from[1]: from[0])/255.0;
					to->b = (float)((channels >= 3)? from[2]: from[0])/255.0;
					to->a = (float)((channels >= 4)? from[3]: from[0])/255.0;
					to++; from += 4;
				}
			}
		}
		
//		printf("OpenEXR-save: Writing OpenEXR file of height %d.\n", height);
		
		file->setFrameBuffer (frameBuffer);				  
		file->writePixels (height);					  
		delete file;
		delete [] pixels;
	}
	catch (const std::exception &exc)
	{      
		printf("OpenEXR-save: ERROR: %s\n", exc.what());
		if (ibuf) IMB_freeImBuf(ibuf);
		
		return (0);
	}
	
	return (1);
}

static short imb_save_openexr_float(struct ImBuf *ibuf, char *name, int flags)
{
	int channels = ibuf->channels;
	int width = ibuf->x;
	int height = ibuf->y;
	int write_zbuf = (flags & IB_zbuffloat) && ibuf->zbuf_float != NULL;   // summarize

	try
	{
		Header header (width, height);
		
		openexr_header_compression(&header, ibuf->ftype & OPENEXR_COMPRESS);
		
		header.channels().insert ("R", Channel (FLOAT));
		header.channels().insert ("G", Channel (FLOAT));
		header.channels().insert ("B", Channel (FLOAT));
		if (ibuf->depth==32 && channels >= 4)
			header.channels().insert ("A", Channel (FLOAT));
		if (write_zbuf)
			header.channels().insert ("Z", Channel (FLOAT));
		
		FrameBuffer frameBuffer;			
		OutputFile *file = new OutputFile(name, header);			
		int xstride = sizeof(float) * channels;
		int ystride = - xstride*width;
		float *rect[4] = {NULL, NULL, NULL, NULL};

		rect[0]= ibuf->rect_float + channels*(height-1)*width;
		rect[1]= (channels >= 2)? rect[0]+1: rect[0];
		rect[2]= (channels >= 3)? rect[0]+2: rect[0];
		rect[3]= (channels >= 4)? rect[0]+3: rect[0];

		frameBuffer.insert ("R", Slice (FLOAT,  (char *)rect[0], xstride, ystride));
		frameBuffer.insert ("G", Slice (FLOAT,  (char *)rect[1], xstride, ystride));
		frameBuffer.insert ("B", Slice (FLOAT,  (char *)rect[2], xstride, ystride));
		if (ibuf->depth==32 && channels >= 4)
			frameBuffer.insert ("A", Slice (FLOAT,  (char *)rect[3], xstride, ystride));
		if (write_zbuf)
			frameBuffer.insert ("Z", Slice (FLOAT, (char *) (ibuf->zbuf_float + (height-1)*width),
											sizeof(float), sizeof(float) * -width));
		file->setFrameBuffer (frameBuffer);				  
		file->writePixels (height);					  
		delete file;
	}
	catch (const std::exception &exc)
	{      
		printf("OpenEXR-save: ERROR: %s\n", exc.what());
		if (ibuf) IMB_freeImBuf(ibuf);
		
		return (0);
	}
	
	return (1);
	//	printf("OpenEXR-save: Done.\n");
}


short imb_save_openexr(struct ImBuf *ibuf, char *name, int flags)
{
	if (flags & IB_mem) 
	{
		printf("OpenEXR-save: Create EXR in memory CURRENTLY NOT SUPPORTED !\n");
		imb_addencodedbufferImBuf(ibuf);
		ibuf->encodedsize = 0;	  
		return(0);
	} 
	
	if (ibuf->ftype & OPENEXR_HALF) 
		return imb_save_openexr_half(ibuf, name, flags);
	else {
		/* when no float rect, we save as half (16 bits is sufficient) */
		if (ibuf->rect_float==NULL)
			return imb_save_openexr_half(ibuf, name, flags);
		else
			return imb_save_openexr_float(ibuf, name, flags);
	}
}

/* ********************* Nicer API, MultiLayer and with Tile file support ************************************ */

/* naming rules:
   - parse name from right to left
   - last character is channel ID, 1 char like 'A' 'R' 'G' 'B' 'X' 'Y' 'Z' 'W' 'U' 'V'
   - separated with a dot; the Pass name (like "Depth", "Color", "Diffuse" or "Combined")
   - separated with a dot: the Layer name (like "Lamp1" or "Walls" or "Characters")
*/

static ListBase exrhandles= {NULL, NULL};

typedef struct ExrHandle {
	struct ExrHandle *next, *prev;
	
	InputFile *ifile;
	TiledOutputFile *tofile;
	OutputFile *ofile;
	int tilex, tiley;
	int width, height;
	int mipmap;
	
	ListBase channels;	/* flattened out, ExrChannel */
	ListBase layers;	/* hierarchical, pointing in end to ExrChannel */
} ExrHandle;

/* flattened out channel */
typedef struct ExrChannel {
	struct ExrChannel *next, *prev;
	
	char name[EXR_TOT_MAXNAME+1];	/* full name of layer+pass */
	int xstride, ystride;		/* step to next pixel, to next scanline */
	float *rect;				/* first pointer to write in */
	char chan_id;				/* quick lookup of channel char */
} ExrChannel;


/* hierarchical; layers -> passes -> channels[] */
typedef struct ExrPass {
	struct ExrPass *next, *prev;
	char name[EXR_PASS_MAXNAME];
	int totchan;
	float *rect;
	struct ExrChannel *chan[EXR_PASS_MAXCHAN];
	char chan_id[EXR_PASS_MAXCHAN];
} ExrPass;

typedef struct ExrLayer {
	struct ExrLayer *next, *prev;
	char name[EXR_LAY_MAXNAME+1];
	ListBase passes;
} ExrLayer;

/* ********************** */

void *IMB_exr_get_handle(void)
{
	ExrHandle *data= (ExrHandle *)MEM_callocN(sizeof(ExrHandle), "exr handle");
	BLI_addtail(&exrhandles, data);
	return data;
}

/* adds flattened ExrChannels */
/* xstride, ystride and rect can be done in set_channel too, for tile writing */
void IMB_exr_add_channel(void *handle, const char *layname, const char *passname, int xstride, int ystride, float *rect)
{
	ExrHandle *data= (ExrHandle *)handle;
	ExrChannel *echan;
	
	echan= (ExrChannel *)MEM_callocN(sizeof(ExrChannel), "exr tile channel");
	
	if(layname) {
		char lay[EXR_LAY_MAXNAME+1], pass[EXR_PASS_MAXNAME+1];
		BLI_strncpy(lay, layname, EXR_LAY_MAXNAME);
		BLI_strncpy(pass, passname, EXR_PASS_MAXNAME);

		sprintf(echan->name, "%s.%s", lay, pass);
	}
	else
		BLI_strncpy(echan->name, passname, EXR_TOT_MAXNAME-1);
	
	echan->xstride= xstride;
	echan->ystride= ystride;
	echan->rect= rect;
	
	// printf("added channel %s\n", echan->name);
	BLI_addtail(&data->channels, echan);
}

void IMB_exr_begin_write(void *handle, char *filename, int width, int height, int compress)
{
	ExrHandle *data= (ExrHandle *)handle;
	Header header (width, height);
	ExrChannel *echan;
	
	data->width= width;
	data->height= height;
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next)
		header.channels().insert (echan->name, Channel (FLOAT));
	
	openexr_header_compression(&header, compress);
	/* header.lineOrder() = DECREASING_Y; this crashes in windows for file read! */
	
	header.insert ("BlenderMultiChannel", StringAttribute ("Blender V2.43 and newer"));
	
	data->ofile = new OutputFile(filename, header);
}

void IMB_exrtile_begin_write(void *handle, char *filename, int mipmap, int width, int height, int tilex, int tiley)
{
	ExrHandle *data= (ExrHandle *)handle;
	Header header (width, height);
	ExrChannel *echan;
	
	data->tilex= tilex;
	data->tiley= tiley;
	data->width= width;
	data->height= height;
	data->mipmap= mipmap;
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next)
		header.channels().insert (echan->name, Channel (FLOAT));
	
	header.setTileDescription (TileDescription (tilex, tiley, (mipmap)? MIPMAP_LEVELS: ONE_LEVEL));
	header.lineOrder() = RANDOM_Y;
	header.compression() = RLE_COMPRESSION;
	
	header.insert ("BlenderMultiChannel", StringAttribute ("Blender V2.43"));
	
	data->tofile = new TiledOutputFile(filename, header);
}

/* read from file */
int IMB_exr_begin_read(void *handle, char *filename, int *width, int *height)
{
	ExrHandle *data= (ExrHandle *)handle;
	
	if(BLI_exists(filename) && BLI_filepathsize(filename)>32) {	/* 32 is arbitrary, but zero length files crashes exr */
		data->ifile = new InputFile(filename);
		if(data->ifile) {
			Box2i dw = data->ifile->header().dataWindow();
			data->width= *width  = dw.max.x - dw.min.x + 1;
			data->height= *height = dw.max.y - dw.min.y + 1;
			
			const ChannelList &channels = data->ifile->header().channels();
			
			for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i)
				IMB_exr_add_channel(data, NULL, i.name(), 0, 0, NULL);
			
			return 1;
		}
	}
	return 0;
}

/* still clumsy name handling, layers/channels can be ordered as list in list later */
void IMB_exr_set_channel(void *handle, char *layname, char *passname, int xstride, int ystride, float *rect)
{
	ExrHandle *data= (ExrHandle *)handle;
	ExrChannel *echan;
	char name[EXR_TOT_MAXNAME + 1];
	
	if(layname) {
		char lay[EXR_LAY_MAXNAME+1], pass[EXR_PASS_MAXNAME+1];
		BLI_strncpy(lay, layname, EXR_LAY_MAXNAME);
		BLI_strncpy(pass, passname, EXR_PASS_MAXNAME);
		
		sprintf(name, "%s.%s", lay, pass);
	}
	else
		BLI_strncpy(name, passname, EXR_TOT_MAXNAME-1);
	
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next)
		if(strcmp(echan->name, name)==0)
			break;
	
	if(echan) {
		echan->xstride= xstride;
		echan->ystride= ystride;
		echan->rect= rect;
	}
	else
		printf("IMB_exrtile_set_channel error %s\n", name);
}

void IMB_exrtile_clear_channels(void *handle)
{
	ExrHandle *data= (ExrHandle *)handle;
	BLI_freelistN(&data->channels);
}

void IMB_exrtile_write_channels(void *handle, int partx, int party, int level)
{
	ExrHandle *data= (ExrHandle *)handle;
	FrameBuffer frameBuffer;
	ExrChannel *echan;
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next) {
		float *rect= echan->rect - echan->xstride*partx - echan->ystride*party;

		frameBuffer.insert (echan->name, Slice (FLOAT,  (char *)rect, 
							echan->xstride*sizeof(float), echan->ystride*sizeof(float)));
	}
	
	data->tofile->setFrameBuffer (frameBuffer);

	try {
		// printf("write tile %d %d\n", partx/data->tilex, party/data->tiley);
		data->tofile->writeTile (partx/data->tilex, party/data->tiley, level);
	}
	catch (const std::exception &exc) {
		std::cerr << "OpenEXR-writeTile: ERROR: " << exc.what() << std::endl;
	}
}

void IMB_exr_write_channels(void *handle)
{
	ExrHandle *data= (ExrHandle *)handle;
	FrameBuffer frameBuffer;
	ExrChannel *echan;
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next)
		frameBuffer.insert (echan->name, Slice (FLOAT,  (char *)echan->rect, 
												echan->xstride*sizeof(float), echan->ystride*sizeof(float)));
	
	data->ofile->setFrameBuffer (frameBuffer);
	data->ofile->writePixels (data->height);	
	
}

void IMB_exr_read_channels(void *handle)
{
	ExrHandle *data= (ExrHandle *)handle;
	FrameBuffer frameBuffer;
	ExrChannel *echan;
	
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next) {
		/* no datawindow correction needed */
		if(echan->rect)
			frameBuffer.insert (echan->name, Slice (FLOAT,  (char *)echan->rect, 
												echan->xstride*sizeof(float), echan->ystride*sizeof(float)));
		else 
			printf("warning, channel with no rect set %s\n", echan->name);
	}
	
	data->ifile->setFrameBuffer (frameBuffer);
	data->ifile->readPixels (0, data->height-1);	
}

void IMB_exr_multilayer_convert(void *handle, void *base,  
								void * (*addlayer)(void *base, char *str), 
								void (*addpass)(void *base, void *lay, char *str, 
												float *rect, int totchan, char *chan_id))
{
	ExrHandle *data= (ExrHandle *)handle;
	ExrLayer *lay;
	ExrPass *pass;

	if(data->layers.first==NULL) {
		printf("cannot convert multilayer, no layers in handle\n");
		return;
	}

	for(lay= (ExrLayer *)data->layers.first; lay; lay= lay->next) {
		void *laybase= addlayer(base, lay->name);
		if(laybase) {
			for(pass= (ExrPass *)lay->passes.first; pass; pass= pass->next) {
				addpass(base, laybase, pass->name, pass->rect, pass->totchan, pass->chan_id);
				pass->rect= NULL;
			}
		}
	}
}


void IMB_exr_close(void *handle)
{
	ExrHandle *data= (ExrHandle *)handle;
	ExrLayer *lay;
	ExrPass *pass;
	
	if(data->ifile)
		delete data->ifile;
	else if(data->ofile)
		delete data->ofile;
	else if(data->tofile)
		delete data->tofile;
	
	data->ifile= NULL;
	data->ofile= NULL;
	data->tofile= NULL;
	
	BLI_freelistN(&data->channels);
	
	for(lay= (ExrLayer *)data->layers.first; lay; lay= lay->next) {
		for(pass= (ExrPass *)lay->passes.first; pass; pass= pass->next)
			if(pass->rect)
				MEM_freeN(pass->rect);
		BLI_freelistN(&lay->passes);
	}
	BLI_freelistN(&data->layers);
	
	BLI_remlink(&exrhandles, data);
	MEM_freeN(data);
}

/* ********* */

static int imb_exr_split_channel_name(ExrChannel *echan, char *layname, char *passname)
{
	int plen, len= strlen(echan->name);
	
	if(len < 4) {
		printf("multilayer read: name too short: %s\n", echan->name);
		return 0;
	}
	if(echan->name[len-2]!='.') {
		printf("multilayer read: name has no Channel: %s\n", echan->name);
		return 0;
	}
	echan->chan_id= echan->name[len-1];
	
	len-= 3;
	while(len>=0) {
		if(echan->name[len]=='.')
			break;
		len--;
	}
	BLI_strncpy(passname, echan->name+len+1, EXR_PASS_MAXNAME);
	plen= strlen(passname);
	if(plen < 3) {
		printf("multilayer read: should not happen: %s\n", echan->name);
		return 0;
	}
	passname[plen-2]= 0;
	
	if(len<1)
		layname[0]= 0;
	else {
		BLI_strncpy(layname, echan->name, EXR_LAY_MAXNAME);
		layname[len]= 0;
	}
	// printf("found lay %s pass %s chan %c\n", layname, passname, echan->chan_id);
	return 1;
}

static ExrLayer *imb_exr_get_layer(ListBase *lb, char *layname)
{
	ExrLayer *lay;
	
	for(lay= (ExrLayer *)lb->first; lay; lay= lay->next) {
		if( strcmp(lay->name, layname)==0 )
			return lay;
	}
	lay= (ExrLayer *)MEM_callocN(sizeof(ExrLayer), "exr layer");
	BLI_addtail(lb, lay);
	BLI_strncpy(lay->name, layname, EXR_LAY_MAXNAME);
	
	return lay;
}

static ExrPass *imb_exr_get_pass(ListBase *lb, char *passname)
{
	ExrPass *pass;
	
	for(pass= (ExrPass *)lb->first; pass; pass= pass->next) {
		if( strcmp(pass->name, passname)==0 )
			return pass;
	}
	
	pass= (ExrPass *)MEM_callocN(sizeof(ExrPass), "exr pass");

	if(strcmp(passname, "Combined")==0)
		BLI_addhead(lb, pass);
	else
		BLI_addtail(lb, pass);
	
	BLI_strncpy(pass->name, passname, EXR_LAY_MAXNAME);
	
	return pass;
}

/* creates channels, makes a hierarchy and assigns memory to channels */
static ExrHandle *imb_exr_begin_read_mem(InputFile *file, int width, int height)
{
	ExrLayer *lay;
	ExrPass *pass;
	ExrChannel *echan;
	ExrHandle *data= (ExrHandle *)IMB_exr_get_handle();
	int a;
	char layname[EXR_TOT_MAXNAME], passname[EXR_TOT_MAXNAME];
	
	data->ifile= file;
	data->width= width;
	data->height= height;
	
	const ChannelList &channels = data->ifile->header().channels();

	for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i)
		IMB_exr_add_channel(data, NULL, i.name(), 0, 0, NULL);
	
	/* now try to sort out how to assign memory to the channels */
	/* first build hierarchical layer list */
	for(echan= (ExrChannel *)data->channels.first; echan; echan= echan->next) {
		if( imb_exr_split_channel_name(echan, layname, passname) ) {
			ExrLayer *lay= imb_exr_get_layer(&data->layers, layname);
			ExrPass *pass= imb_exr_get_pass(&lay->passes, passname);
			
			pass->chan[pass->totchan]= echan;
			pass->totchan++;
			if(pass->totchan>=EXR_PASS_MAXCHAN)
				break;
		}
	}
	if(echan) {
		printf("error, too many channels in one pass: %s\n", echan->name);
		IMB_exr_close(data);
		return NULL;
	}
	
	/* with some heuristics, try to merge the channels in buffers */
	for(lay= (ExrLayer *)data->layers.first; lay; lay= lay->next) {
		for(pass= (ExrPass *)lay->passes.first; pass; pass= pass->next) {
			if(pass->totchan) {
				pass->rect= (float *)MEM_mapallocN(width*height*pass->totchan*sizeof(float), "pass rect");
				if(pass->totchan==1) {
					echan= pass->chan[0];
					echan->rect= pass->rect;
					echan->xstride= 1;
					echan->ystride= width;
					pass->chan_id[0]= echan->chan_id;
				}
				else {
					char lookup[256];
					
					memset(lookup, 0, sizeof(lookup));
						   
					/* we can have RGB(A), XYZ(W), UVA */
					if(pass->totchan==3 || pass->totchan==4) {
						if(pass->chan[0]->chan_id=='B' || pass->chan[1]->chan_id=='B' ||  pass->chan[2]->chan_id=='B') {
							lookup[(unsigned int)'R']= 0;
							lookup[(unsigned int)'G']= 1;
							lookup[(unsigned int)'B']= 2;
							lookup[(unsigned int)'A']= 3;
						}
						else if(pass->chan[0]->chan_id=='Y' || pass->chan[1]->chan_id=='Y' ||  pass->chan[2]->chan_id=='Y') {
							lookup[(unsigned int)'X']= 0;
							lookup[(unsigned int)'Y']= 1;
							lookup[(unsigned int)'Z']= 2;
							lookup[(unsigned int)'W']= 3;
						}
						else {
							lookup[(unsigned int)'U']= 0;
							lookup[(unsigned int)'V']= 1;
							lookup[(unsigned int)'A']= 2;
						}
						for(a=0; a<pass->totchan; a++) {
							echan= pass->chan[a];
							echan->rect= pass->rect + lookup[(unsigned int)echan->chan_id];
							echan->xstride= pass->totchan;
							echan->ystride= width*pass->totchan;
							pass->chan_id[ (unsigned int)lookup[(unsigned int)echan->chan_id] ]= echan->chan_id;
						}
					}
					else { /* unknown */
						for(a=0; a<pass->totchan; a++) {
							echan= pass->chan[a];
							echan->rect= pass->rect + a;
							echan->xstride= pass->totchan;
							echan->ystride= width*pass->totchan;
							pass->chan_id[a]= echan->chan_id;
						}
					}
				}
			}
		}
	}
	
	return data;
}


/* ********************************************************* */

typedef struct RGBA
{
	float r;
	float g;
	float b;
	float a;
} RGBA;


/* debug only */
static void exr_print_filecontents(InputFile *file)
{
	const ChannelList &channels = file->header().channels();
	
	for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i)
	{
		const Channel &channel = i.channel();
		printf("OpenEXR-load: Found channel %s of type %d\n", i.name(), channel.type);
	}
}

/* for non-multilayer, map  R G B A channel names to something that's in this file */
static const char *exr_rgba_channelname(InputFile *file, const char *chan)
{
	const ChannelList &channels = file->header().channels();
	
	for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i)
	{
		const char *str= i.name();
		int len= strlen(str);
		if(len) {
			if(BLI_strcasecmp(chan, str+len-1)==0) {
				return str;
			}
		}
	}
	return chan;
}



static int exr_has_zbuffer(InputFile *file)
{
	const ChannelList &channels = file->header().channels();
	
	for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i)
	{
		if(strcmp("Z", i.name())==0)
			return 1;
	}
	return 0;
}

static int exr_is_renderresult(InputFile *file)
{
	const StringAttribute *comments= file->header().findTypedAttribute<StringAttribute>("BlenderMultiChannel");
	if(comments)
//		if(comments->value() == "Blender MultiChannel")
			return 1;
	return 0;
}

struct ImBuf *imb_load_openexr(unsigned char *mem, int size, int flags)
{
	struct ImBuf *ibuf = NULL;
	InputFile *file = NULL;
	
	if (imb_is_a_openexr(mem) == 0) return(NULL);
	
	try
	{
		Mem_IStream *membuf = new Mem_IStream(mem, size); 
		int is_multi;
		file = new InputFile(*membuf);
		
		Box2i dw = file->header().dataWindow();
		int width  = dw.max.x - dw.min.x + 1;
		int height = dw.max.y - dw.min.y + 1;
		
		//printf("OpenEXR-load: image data window %d %d %d %d\n", 
		//	   dw.min.x, dw.min.y, dw.max.x, dw.max.y);

		if(0) // debug
			exr_print_filecontents(file);
		
		is_multi= exr_is_renderresult(file);
		
		/* do not make an ibuf when */
		if(is_multi && !(flags & IB_test) && !(flags & IB_multilayer)) 
		{
			printf("Error: can't process EXR multilayer file\n");
		}
		else {
		
			ibuf = IMB_allocImBuf(width, height, 32, 0, 0);
			ibuf->ftype = OPENEXR;
			
			if (!(flags & IB_test))
			{
				if(is_multi) /* only enters with IB_multilayer flag set */
				{
					/* constructs channels for reading, allocates memory in channels */
					ExrHandle *handle= imb_exr_begin_read_mem(file, width, height);
					if(handle) {
						IMB_exr_read_channels(handle);
						ibuf->userdata= handle;			/* potential danger, the caller has to check for this! */
						return ibuf;
					}
				}
				else {
					FrameBuffer frameBuffer;
					float *first;
					int xstride = sizeof(float) * 4;
					int ystride = - xstride*width;
					
					imb_addrectfloatImBuf(ibuf);
					
					/* inverse correct first pixel for datawindow coordinates (- dw.min.y because of y flip) */
					first= ibuf->rect_float - 4*(dw.min.x - dw.min.y*width);
					/* but, since we read y-flipped (negative y stride) we move to last scanline */
					first+= 4*(height-1)*width;
					
					frameBuffer.insert ( exr_rgba_channelname(file, "R"), 
										Slice (FLOAT,  (char *) first, xstride, ystride));
					frameBuffer.insert ( exr_rgba_channelname(file, "G"), 
										Slice (FLOAT,  (char *) (first+1), xstride, ystride));
					frameBuffer.insert ( exr_rgba_channelname(file, "B"), 
										Slice (FLOAT,  (char *) (first+2), xstride, ystride));
																			
					frameBuffer.insert ( exr_rgba_channelname(file, "A"), 
										Slice (FLOAT,  (char *) (first+3), xstride, ystride, 1, 1, 1.0f)); /* 1.0 is fill value */

					if(exr_has_zbuffer(file)) 
					{
						float *firstz;
						
						addzbuffloatImBuf(ibuf);
						firstz= ibuf->zbuf_float - (dw.min.x - dw.min.y*width);
						firstz+= (height-1)*width;
						frameBuffer.insert ("Z", Slice (FLOAT,  (char *)firstz , sizeof(float), -width*sizeof(float)));
					}
					
					file->setFrameBuffer (frameBuffer);
					file->readPixels (dw.min.y, dw.max.y);
					
					IMB_rect_from_float(ibuf);
				}
			}
			
		}
		delete file;
		
		return(ibuf);
				
	}
	catch (const std::exception &exc)
	{
		std::cerr << exc.what() << std::endl;
		if (ibuf) IMB_freeImBuf(ibuf);
		delete file;
		
		return (0);
	}
	
}


} // export "C"