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'''OpenGL extension NV.framebuffer_mixed_samples
This module customises the behaviour of the
OpenGL.raw.GL.NV.framebuffer_mixed_samples to provide a more
Python-friendly API
Overview (from the spec)
This extension allows multisample rendering with a raster and
depth/stencil sample count that is larger than the color sample count.
Rasterization and the results of the depth and stencil tests together
determine the portion of a pixel that is "covered". It can be useful to
evaluate coverage at a higher frequency than color samples are stored.
This coverage is then "reduced" to a collection of covered color samples,
each having an opacity value corresponding to the fraction of the color
sample covered. The opacity can optionally be blended into individual
color samples.
In the current hardware incarnation both depth and stencil testing are
supported with mixed samples, although the API accommodates supporting
only one or the other.
Rendering with fewer color samples than depth/stencil samples can greatly
reduce the amount of memory and bandwidth consumed by the color buffer.
However, converting the coverage values into opacity can introduce
artifacts where triangles share edges and may not be suitable for normal
triangle mesh rendering.
One expected use case for this functionality is Stencil-then-Cover path
rendering (NV_path_rendering). The stencil step determines the coverage
(in the stencil buffer) for an entire path at the higher sample frequency,
and then the cover step can draw the path into the lower frequency color
buffer using the coverage information to antialias path edges. With this
two-step process, internal edges are fully covered when antialiasing is
applied and there is no corruption on these edges.
The key features of this extension are:
- It allows a framebuffer object to be considered complete when its depth
or stencil samples are a multiple of the number of color samples.
- It redefines SAMPLES to be the number of depth/stencil samples (if any);
otherwise, it uses the number of color samples. SAMPLE_BUFFERS is one if
there are multisample depth/stencil attachments. Multisample
rasterization and multisample fragment ops are allowed if SAMPLE_BUFFERS
is one.
- It replaces several error checks involving SAMPLE_BUFFERS by error
checks directly referencing the number of samples in the relevant
attachments.
- A coverage reduction step is added to Per-Fragment Operations which
converts a set of covered raster/depth/stencil samples to a set of
covered color samples. The coverage reduction step also includes an
optional coverage modulation step, multiplying color values by a
fractional opacity corresponding to the number of associated
raster/depth/stencil samples covered.
The official definition of this extension is available here:
http://www.opengl.org/registry/specs/NV/framebuffer_mixed_samples.txt
'''
from OpenGL import platform, constant, arrays
from OpenGL import extensions, wrapper
import ctypes
from OpenGL.raw.GL import _types, _glgets
from OpenGL.raw.GL.NV.framebuffer_mixed_samples import *
from OpenGL.raw.GL.NV.framebuffer_mixed_samples import _EXTENSION_NAME
def glInitFramebufferMixedSamplesNV():
'''Return boolean indicating whether this extension is available'''
from OpenGL import extensions
return extensions.hasGLExtension( _EXTENSION_NAME )
# INPUT glCoverageModulationTableNV.v size not checked against n
glCoverageModulationTableNV=wrapper.wrapper(glCoverageModulationTableNV).setInputArraySize(
'v', None
)
### END AUTOGENERATED SECTION
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