Work in progress commit on saving OpenEXR with all render-layers and

passes in single file. Code is currently disabled, commit is mainly to
have a nicer method of excluding OpenEXR dependency from render module.
This should compile with disabled WITH_OPENEXR too.

Reason why EXR is great to include by default in Blender is its feature
to store unlimited layers and channels, and write this tile based. I
need the feature for saving memory; while rendering tiles, all full-size
buffers for all layers and passes are kept in memory now, which can go
into 100s of MB easily.
The code I commit now doesn't allocate these buffers while rendering, but
saves the tiles to disk. In the end is it read back. Overhead for large
renders (like 300 meg buffers) is 10-15 seconds, not bad.

Two more interesting aspects:
- Blender can save such multi-layer files in the temp directory, storing
it with .blend file name and scene name. That way, on each restart of Blender,
or on switching scenes, these buffers can be read. So you always see what was
rendered last. Also great for compositing work.
- This can also become an output image type for rendering. There's plenty of
cases where you want specific layers or passes saved to disk for later use.

Anyhoo, finishing it is another days of work, and I got more urgent stuff
now!

1 files changed, 74 insertions, 0 deletions

diff --git a/source/blender/imbuf/intern/openexr/openexr_multi.h b/source/blender/imbuf/intern/openexr/openexr_multi.h
new file mode 100644
index 00000000000..ff71aab5f3c
--- /dev/null
+++ b/source/blender/imbuf/intern/openexr/openexr_multi.h
@@ -0,0 +1,74 @@
+/**
+ * $Id$ 
+ *
+ * ***** BEGIN GPL LICENSE 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.
+ *
+ * The Original Code is Copyright (C) 2006 Blender Foundation
+ * All rights reserved.
+ *
+ * The Original Code is: all of this file.
+ *
+ * Contributor(s): Ton Roosendaal.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#ifndef _OPENEXR_MULTI_H
+#define _OPENEXR_MULTI_H
+
+/* experiment with more advanced exr api */
+
+#ifdef WITH_OPENEXR
+void *	IMB_exr_get_handle			(void);
+void	IMB_exr_add_channel			(void *handle, const char *layname, const char *channame);
+
+int		IMB_exr_begin_read			(void *handle, char *filename, int *width, int *height);
+void	IMB_exr_begin_write			(void *handle, char *filename, int width, int height);
+void	IMB_exrtile_begin_write		(void *handle, char *filename, int width, int height, int tilex, int tiley);
+
+void	IMB_exr_set_channel			(void *handle, char *layname, char *channame, int xstride, int ystride, float *rect);
+
+void	IMB_exr_read_channels		(void *handle);
+void	IMB_exr_write_channels		(void *handle);
+void	IMB_exrtile_write_channels	(void *handle, int partx, int party);
+
+void	IMB_exr_close				(void *handle);
+
+#else
+
+/* ugly... but we only use it on pipeline.c, render module, now */
+
+void *	IMB_exr_get_handle			(void) {return NULL;}
+void	IMB_exr_add_channel			(void *handle, const char *layname, const char *channame) {}
+
+int		IMB_exr_begin_read			(void *handle, char *filename, int *width, int *height) {return 0;}
+void	IMB_exr_begin_write			(void *handle, char *filename, int width, int height) {}
+void	IMB_exrtile_begin_write		(void *handle, char *filename, int width, int height, int tilex, int tiley) {}
+
+void	IMB_exr_set_channel			(void *handle, char *layname, char *channame, int xstride, int ystride, float *rect) {}
+
+void	IMB_exr_read_channels		(void *handle) {}
+void	IMB_exr_write_channels		(void *handle) {}
+void	IMB_exrtile_write_channels	(void *handle, int partx, int party) {}
+
+void	IMB_exr_close				(void *handle) {}
+
+#endif
+
+
+
+#endif /* __OPENEXR_MULTI_H */