Glf fails to read half-float EXR images

[sourimantg]

Description of Issue

While using Glf to read input EXR files, in which each channel is encoded as a half float (tpypical use-case: environment lights), a segmentation fault occurs.

Steps to Reproduce

1. Properly setup Glf for image reading

pxr::GlfImageSharedPtr image = pxr::GlfImage::OpenForReading(texName);
pxr::GlfImage::StorageSpec storage;
[...]
image->Read(storage); // <- segfault happens here

texName refers to a valid, resolved path to an EXR image with half float channels.
storage is initialized properly.

Solution proposal

The problem seems to come from the method _GetOIIOBaseType(GLenum type), in the file oiioImage.cpp. The conversion between a GLenum and a TypeDesc is missing the half float case. The implementation should look something like this:

/// Converts a GL type into its OpenImageIO component type equivalent.
static TypeDesc
_GetOIIOBaseType(GLenum type)
{
    switch (type) {
    case GL_UNSIGNED_BYTE:
    case GL_BYTE:
        return TypeDesc::UINT8;
    case GL_UNSIGNED_INT:
    case GL_INT:
        return TypeDesc::UINT;
    case GL_HALF_FLOAT:        // new line
        return TypeDesc::HALF; // new line
    case GL_FLOAT:
        return TypeDesc::FLOAT;
    default:
        TF_CODING_ERROR("Unsupported type");
        return TypeDesc::FLOAT;
    }
}

It's worth noting that the reverse conversion implemented in _GLTypeFromImageData(TypeDesc typedesc) properly addresses the half float case.

Applying this modification solves the problem on my tests.

System Information (OS, Hardware)

Windows 7, but should be similar on other platforms

Package Versions

0.8.5a, not tested on dev branch but according to a git blame, the problem should be in this branch too.

Build Flags

(stripped the directory-related directives)

cmake -G "Visual Studio 14 2015 Win64"
-DBoost_NO_SYSTEM_PATHS=ON 
-DPXR_ENABLE_PYTHON_SUPPORT=ON 
-DBUILD_SHARED_LIBS=ON 
-DPXR_BUILD_DOCUMENTATION=OFF 
-DPXR_BUILD_TESTS=OFF
-DPXR_BUILD_IMAGING=ON 
-DPXR_ENABLE_PTEX_SUPPORT=OFF 
-DPXR_BUILD_EMBREE_PLUGIN=OFF 
-DPXR_BUILD_USD_IMAGING=ON 
-DPXR_BUILD_ALEMBIC_PLUGIN=OFF 
-DPXR_BUILD_MAYA_PLUGIN=ON 
-DPXR_BUILD_KATANA_PLUGIN=OFF 
-DPXR_BUILD_HOUDINI_PLUGIN=OFF 
-DCMAKE_CXX_FLAGS="/Zm150"

[jtran56]

Filed as internal issue #164138.