GPU: Add Image property to allow high bitdepth support on a per image basis

This adds the `Half Float Precision` option in the image property panel.
This option is only available on float textures and is enabled by default.

Adding a flag inside the imbuf (IB_halffloat) on load is done for EXR and PSD formats that can store half floating point (16bits/channels).
The option is then not displayed in this case and forced.

Related task T73086

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D6891

3 files changed, 17 insertions, 1 deletions

diff --git a/source/blender/imbuf/IMB_imbuf_types.h b/source/blender/imbuf/IMB_imbuf_types.h
index 61aa1f401a0..0568c425e78 100644
--- a/source/blender/imbuf/IMB_imbuf_types.h
+++ b/source/blender/imbuf/IMB_imbuf_types.h
@@ -291,6 +291,7 @@ enum {
   IB_alphamode_ignore = 1 << 15,
   IB_thumbnail = 1 << 16,
   IB_multiview = 1 << 17,
+  IB_halffloat = 1 << 18,
 };
 
 /** \} */
diff --git a/source/blender/imbuf/intern/oiio/openimageio_api.cpp b/source/blender/imbuf/intern/oiio/openimageio_api.cpp
index e001b8b21c4..4746cec41d4 100644
--- a/source/blender/imbuf/intern/oiio/openimageio_api.cpp
+++ b/source/blender/imbuf/intern/oiio/openimageio_api.cpp
@@ -194,7 +194,7 @@ struct ImBuf *imb_load_photoshop(const char *filename, int flags, char colorspac
 {
   struct ImBuf *ibuf = NULL;
   int width, height, components;
-  bool is_float, is_alpha;
+  bool is_float, is_alpha, is_half;
   int basesize;
   char file_colorspace[IM_MAX_SPACE];
   const bool is_colorspace_manually_set = (colorspace[0] != '\0');
@@ -243,6 +243,7 @@ struct ImBuf *imb_load_photoshop(const char *filename, int flags, char colorspac
   is_alpha = spec.alpha_channel != -1;
   basesize = spec.format.basesize();
   is_float = basesize > 1;
+  is_half = spec.format == TypeDesc::HALF;
 
   /* we only handle certain number of components */
   if (!(components >= 1 && components <= 4)) {
@@ -271,6 +272,7 @@ struct ImBuf *imb_load_photoshop(const char *filename, int flags, char colorspac
   ibuf->ftype = IMB_FTYPE_PSD;
   ibuf->channels = 4;
   ibuf->planes = (3 + (is_alpha ? 1 : 0)) * 4 << basesize;
+  ibuf->flags |= (is_float && is_half) ? IB_halffloat : 0;
 
   try {
     return ibuf;
diff --git a/source/blender/imbuf/intern/openexr/openexr_api.cpp b/source/blender/imbuf/intern/openexr/openexr_api.cpp
index e1513169736..9fa2c7a28c5 100644
--- a/source/blender/imbuf/intern/openexr/openexr_api.cpp
+++ b/source/blender/imbuf/intern/openexr/openexr_api.cpp
@@ -1757,6 +1757,18 @@ static bool exr_has_alpha(MultiPartInputFile &file)
   return !(file.header(0).channels().findChannel("A") == NULL);
 }
 
+static bool exr_is_half_float(MultiPartInputFile &file)
+{
+  const ChannelList &channels = file.header(0).channels();
+  for (ChannelList::ConstIterator i = channels.begin(); i != channels.end(); ++i) {
+    const Channel &channel = i.channel();
+    if (channel.type != HALF) {
+      return false;
+    }
+  }
+  return true;
+}
+
 static bool imb_exr_is_multilayer_file(MultiPartInputFile &file)
 {
   const ChannelList &channels = file.header(0).channels();
@@ -1909,6 +1921,7 @@ struct ImBuf *imb_load_openexr(const unsigned char *mem,
       const int is_alpha = exr_has_alpha(*file);
 
       ibuf = IMB_allocImBuf(width, height, is_alpha ? 32 : 24, 0);
+      ibuf->flags |= exr_is_half_float(*file) ? IB_halffloat : 0;
 
       if (hasXDensity(file->header(0))) {
         ibuf->ppm[0] = xDensity(file->header(0)) * 39.3700787f;