Graphics Reference
In-Depth Information
implement a fixed function pipeline and are derived from the OpenGL 1.3
and 1.5 specifications, respectively.
The OpenGL ES 2.0 specification implements a programmable graphics
pipeline and is derived from the OpenGL 2.0 specification. Being derived
from a revision of the OpenGL specification means that the corresponding
OpenGL specification was used as the baseline for determining the feature
set included in the particular revision of OpenGL ES.
OpenGL ES 3.0 is the next step in the evolution of handheld graphics and
is derived from the OpenGL 3.3 specification. While OpenGL ES 2.0 was
successful in bringing capabilities similar to DirectX9 and the Microsoft
Xbox 360 to handheld devices, graphics capabilities have continued to
evolve on desktop GPUs. Significant features that enable techniques such
as shadow mapping, volume rendering, GPU-based particle animation,
geometry instancing, texture compression, and gamma correction were
missing from OpenGL ES 2.0. OpenGL ES 3.0 brings these features to
handheld devices, while continuing the philosophy of adapting to the
constraints of embedded systems.
Of course, some of the constraints that were taken into consideration
while designing previous versions of OpenGL ES are no longer relevant
today. For example, handheld devices now feature large screen sizes (some
offer a higher resolution than most desktop PC monitors). Additionally,
many handheld devices now feature high-performance multicore CPUs
and large amounts of memory. The focus for the Khronos Group in
developing OpenGL ES 3.0 shifted toward appropriate market timing of
features relevant to handheld applications rather than addressing the
limited capabilities of devices.
The following sections introduce the OpenGL ES 3.0 pipeline.
As noted earlier, OpenGL ES 3.0 is the API covered in this topic. Our
goal is to cover the OpenGL ES 3.0 specification in thorough detail, give
specific examples of how to use the features in OpenGL ES 3.0, and discuss
various performance optimization techniques. After reading this topic, you
should have an excellent grasp of the OpenGL ES 3.0 API, be able to easily
write compelling OpenGL ES 3.0 applications, and not have to worry
about reading multiple specifications to understand how a feature works.
OpenGL ES 3.0 implements a graphics pipeline with programmable
shading and consists of two specifications: the
OpenGL ES 3.0
