O'Reilly logo

OpenGL Insights by Christophe Riccio, Patrick Cozzi

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

III
Bending the
Pipeline
Today GPUs a re masters of performance, considering either high-end desktop
GPUs or even mobile GPUs, which deliver an unbelievable amount of graphics rel-
ative to the power consumption. The future of graphics raises a lot of question
regarding how to scale performance, doing more with less. Based on research on
petascale and exoscale supercomputers, we notice that such a scale of performance
forces us to reconsider memory, bandwidth, and data movement. Challenges are
ahead for GPU innovations. Under the name “bending the pipeline,” we include all
ideas that push the graphics pipeline to explore alternative ways to feed the rendering
pipeline.
We start with two classic techniques. The first one, “Real-Time Physically-Based
Deformation Using Tr ansform Feedback,” presented by Muhammad Mobeen Mova-
nia and Lin Feng, explores the OpenGL transform feedback for GPU-based physical
simulation. The second technique, “Hierarchical Depth-Culling and Bounding-Box
Management on GPU,” presented by Dzmitry Malyshau, presents a method based
on the depth buffer and bounding boxes to discard invisible objects before the actual
rendering even starts.
Maybe shadow mapping is a way to bend the pipeline, but Daniel R´akos certainly
pushes it further in his chapter “Massive Number of Shadows with Layered Render-
ing” with a rendering method allowing him to generate multiple shadow maps per
draw call thanks to layered rendering.
In their chapter “Efficient Layered Fragment Buffer Techniques,” Pyarelal
Knowles, Geoff Leach, and Fabio Zambetta lead us to explore one of the most inter-
esting innovations of OpenGL 4 hardware, image load store, and atomic operations,
through an example of order-independent transparency with a special highlight of
performance resulting from different approaches.
229
230 III Bending the Pipeline
One step further into innovation, Daniel R´akos introduces “Programmable Ver-
tex Pulling,” a radical change of perspective, where we dont submit work to the
GPU, but let the GPU query the work. No doubt this approach will evolve and gain
a lot of importance in the years to come.
If pushing the boundaries of today’s graphics requires a shift in paradigm, bring-
ing new asset representations might be an answer. This is the direction of the work
on Gigavoxels of Cyril Crassin and Simon Green. For their OpenGL Insights chapter
“Octree-Ba sed Sparse Voxelization Using the GPU,” they explain how a GPU may
be efficiently used to build voxel-based representation.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required