Both of the new extensions are written against the OpenGL 4.4 specification.
The first extension, GL_AMD_gpu_shader_int64, for supporting 64-bit integers in an easier manner than NVIDIA's NV_gpu_shader5.
This extension was developed based on the NV_gpu_shader5 extension to allow implementations supporting 64-bit integers to expose the feature without the additional requirements that are present in NV_gpu_shader5.
The extension introduces the following features for all shader types:
* support for 64-bit scalar and vector integer data types, including uniform API, uniform buffer object, transform feedback, and shader input and output support;
* new built-in functions to pack and unpack 64-bit integer types into a two-component 32-bit integer vector;
* new built-in functions to convert double-precision floating-point values to or from their 64-bit integer bit encodings;
* vector relational functions supporting comparisons of vectors of 64-bit integer types; and
* common functions abs, sign, min, max, clamp, and mix supporting arguments of 64-bit integer types.
This extension is designed to be a functional superset of the 64-bit integer support introduced by NV_gpu_shader5 and to be source code compatible with that, thus the new procedures, functions, and tokens are identical to those found in that extension.
The second new AMD OpenGL extension published today is GL_AMD_transform_feedback4. This second extension enhances OpenGL's transform feedback in allowing multiple TF streams to be captured and allows any combination of streams to be rasterized.
Transform feedback is a mechanism to record the output of the vertex, tessellation evaluation or geometry shader into one or more buffers for further processing, recursive rendering or read-back by the client. ARB_transform_feedback3 (and OpenGL 4.0) extended the transform feedback subsystem to allow multiple streams of primitive information to be captured. However, it imposed a limitation that the primitive type for all streams must be POINTS if more than one stream is to be captured. AMD_transform_feedback3_lines_triangles relaxed that restriction to allow lines or triangles to be captured, in the case where multiple streams are to be processed. However, it still required that all streams share the same primitive type. Additionally, with all current extensions to transform feedback, only a single primitive stream may be rasterized.
This extension enhances transform feedback in two significant ways. First, it allows multiple transform feedback streams to be captured, each with its own, independent primitve type. Second, it allows any combination of streams to be rasterized. As an example, this enables the geometry shader to take a single stream of triangle geometry and emit filled triangles with a wireframe outline and a point at each vertex, all in a single pass through the input vertices. Combined with features such those provided by ARB_viewport_array, layered rendering, shader subroutines and so on, an application can render several views of its geoemtry, each with a radically different style, all in a single pass.
On a semi-related note, see my Linux coverage from GDC 2014 that happened last month in San Francisco where we learned various new AMD Linux plans, including a more open Linux driver strategy.