The goal is to solve confusion of the "All rights reserved" for licensing
code under an open-source license.
The phrase "All rights reserved" comes from a historical convention that
required this phrase for the copyright protection to apply. This convention
is no longer relevant.
However, even though the phrase has no meaning in establishing the copyright
it has not lost meaning in terms of licensing.
This change makes it so code under the Blender Foundation copyright does
not use "all rights reserved". This is also how the GPL license itself
states how to apply it to the source code:
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software ...
This change does not change copyright notice in cases when the copyright
is dual (BF and an author), or just an author of the code. It also does
mot change copyright which is inherited from NaN Holding BV as it needs
some further investigation about what is the proper way to handle it.
This PR adds basic support for texture update, read back and clearing
for Vulkan. In Vulkan we need to convert each data type ourselves as
vulkan buffers are untyped. Therefore this change mostly is about data
conversions.
Considerations:
- Use a compute shader to do the conversions:
- Leads to performance regression as compute pipeline can stall
graphics pipeline
- Lead to additional memory usage as two staging buffers are needed
one to hold the CPU data, and one to hold the converted data.
- Do inline conversion when sending the data to Vulkan using `eGPUDataFormat`
- Additional CPU cycles required and not easy to optimize as it the
implementation requires many branches.
- Do inline conversion when sending the data to Vulkan (optimized for CPU)
For this solution it was chosen to implement the 3rd option as it is fast
and doesn't require additional memory what the other options do.
**Use Imath/half.h**
This patch uses `Imath/half.h` (dependency of OpenEXR) similar to
alembic. But this makes vulkan dependent of the availability of
OpenEXR. For now this isn't checked, but when we are closer to
a working Vulkan backend we have to make a decision how to cope with
this dependency.
**Missing Features**
*Framebuffer textures*
This doesn't include all possible data transformations. Some of those
transformation can only be tested after the VKFramebuffer has been
implemented. Some texture types are only available when created for a
framebuffer. These include the depth and stencil variations.
*Component format*
Is more relevant when implementing VKVertexBuffer.
*SRGB textures*
SRGB encoded textures aren't natively supported on all platforms, in
all usages and might require workarounds. This should be done in a
separate PR in a later stage when we are required to use SRGB textures.
**Test cases**
The added test cases gives an overview of the missing bits and pieces of
the patch. When the implementation/direction is accepted more test cases
can be enabled/implemented.
Some of these test cases will skip depending on the actual support of
platform the tests are running on. For example OpenGL/NVidia will skip
the next test as it doesn't support the texture format on OpenGL, although
it does support it on Vulkan.
```
[ RUN ] GPUOpenGLTest.texture_roundtrip__GPU_DATA_2_10_10_10_REV__GPU_RGB10_A2UI
[ SKIPPED ] GPUOpenGLTest.texture_roundtrip__GPU_DATA_2_10_10_10_REV__GPU_RGB10_A2UI [ RUN ] GPUVulkanTest.texture_roundtrip__GPU_DATA_2_10_10_10_REV__GPU_RGB10_A2UI
[ OK ] GPUVulkanTest.texture_roundtrip__GPU_DATA_2_10_10_10_REV__GPU_RGB10_A2UI
```
Pull Request: https://projects.blender.org/blender/blender/pulls/105762
