The Rendering Pipeline - Practical Rendering and Computation with Direct3D 11 - page 195

application development. The other main debugging tool for Direct3D 11 applications, the
PIX tool, is used primarily for offline analysis of data. This makes streaming of pipeline
data an appropriate method for providing live debugging information. In addition, the use
of the stream output functionality allows for saving intermediate values from within the
geometry shader, which are typically not available for reading in PIX.
3.9.4 Stream Output Pipeline Output
Since the stream output stage doesn't have another stage attached to its output, we can
consider its output as consisting of the data streamed to the buffers. This is just one of
several ways to extract data from the pipeline, but depending on the configuration of the
pipeline, it can be used as the primary output. For example, the pipeline could be used as a
transformation and tessellation accelerator for a software-based rendering system. In such
a scenario, the geometry that will be rendered would be transformed and tessellated by the
GPU and then would be streamed out and read back to the CPU, where it could be used in
the software renderer. The geometry would never be rasterized by Direct3D 11, but could
instead be rendered with a ray-tracing engine or some other high-quality techniques not
available on the GPU.
3.10 Rasterizer
The geometry shader stage marks the final point in the pipeline that deals strictly with geo-
metric data. Regardless of whether it receives data directly from the vertex shader stage,
the domain shader stage, or the geometry shader stage, the geometric pipeline data is fed
into the rasterizer stage. The location of the rasterizer stage is highlighted in Figure 3.45.
The primary purpose of this stage is to convert the geometric data into a regularly
sampled representation that can later be applied to a render target. This sampling process
Figure 3.45. The rasterizer stage.