commit | 0aca3ca9427d1d2aa8d8e706de62360c61af3598 | [log] [tgz] |
---|---|---|
author | Nicolas Capens <capn@google.com> | Sat Sep 19 23:59:08 2020 -0400 |
committer | Nicolas Capens <nicolascapens@google.com> | Fri Oct 09 17:46:41 2020 +0000 |
tree | 27e5cb452d10ed9636a837a859180228cd4820df | |
parent | e8ce1f839b1f5a7c4e5b97c89c8e22bfbac40ff4 [diff] |
Fix depth bias calculations We were simply adding the constant depth bias to the z coordinate, instead of interpreting it as relative to the minimum resolvable difference. In the legacy OpenGL ES code stack we're multiplying it by 2^-23, but this assumes a 32-bit floating-point depth format, while Vulkan must also support 16-bit integer depth, and doesn't take the exponent of the z values of the polygon into account. This change fixes the issue for both integer depth formats, which have a constant minimum resolvable difference, and floating-point depth formats, where the maximum exponent of the z values is used to determine the minimum resolvable difference per polygon. The viewport's depth range transform was corrected to be performed before the depth bias offset. Also the depth bias clamp operation was corrected to be performed only on the bias value, not the polygon's z value for vertex 0. We were also converting scalars to vectors a bit earlier than necessary, so this was refactored to happen later to simplify the calculations. The bias is added per fragment, after z interpolation, instead of being added to the 'C' factor of the plane equation. That's because we compute 'y * B + C' per row, and then add 'x * A' per fragment. When the bias is included in 'C', the additions cause loss of precision greater than the minimum resolvable difference, and dEQP-GLES3.functional.polygon_offset fails because it uses a 'units' depth bias of 1. Note this change is intentionally unoptimized, to serve as a spec- compliant reference implementation. dEQP has poor test coverage for this functionality so we need to start off with something that is easy to reference against the spec. Bug: b/139341727 Fixes: b/160463658 Change-Id: Ief1dd609d8ac974e76b1b785a924b09b448297a2 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/48629 Presubmit-Ready: Nicolas Capens <nicolascapens@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com> Kokoro-Result: kokoro <noreply+kokoro@google.com> Reviewed-by: Antonio Maiorano <amaiorano@google.com>
SwiftShader is a high-performance CPU-based implementation of the Vulkan graphics APIs12. Its goal is to provide hardware independence for advanced 3D graphics.
NOTE: SwiftShader's OpenGL ES frontend is no longer supported, and will eventually be removed. Read more about our recommendation to use ANGLE on top of SwiftShader Vulkan here.
SwiftShader libraries can be built for Windows, Linux, and Mac OS X.
Android and Chrome (OS) build environments are also supported.
CMake
Install CMake for Linux, Mac OS X, or Windows and use either the GUI or run the following terminal commands:
cd build cmake .. cmake --build . --parallel ./vk-unittests
Visual Studio
To build the Vulkan ICD library, use Visual Studio 2019 to open the project folder and wait for it to run CMake. Open the CMake Targets View in the Solution Explorer and select the vk_swiftshader project to build it.
The SwiftShader libraries act as drop-in replacements for graphics drivers.
On Windows, most applications can be made to use SwiftShader's DLLs by placing them in the same folder as the executable. On Linux, the LD_LIBRARY_PATH
environment variable or -rpath
linker option can be used to direct applications to search for shared libraries in the indicated directory first.
In general, Vulkan applications look for a shared library named vulkan-1.dll
on Windows (vulkan-1.so
on Linux). SwiftShader's equivalent is named libvk_swiftshader.dll
, which can be renamed to vulkan-1.dll
. Alternatively, you can set the VK_ICD_FILENAMES
environment variable to the path to vk_swiftshader_icd.json
file that is generated under the build directory (e.g. .\SwiftShader\build\Windows\vk_swiftshader_icd.json
). To learn more about how Vulkan loading works, read the official documentation here.
See CONTRIBUTING.txt for important contributing requirements.
The canonical repository for SwiftShader is hosted at: https://swiftshader.googlesource.com/SwiftShader
All changes must be reviewed and approved in the Gerrit review tool at: https://swiftshader-review.googlesource.com
Authenticate your account here: https://swiftshader-review.googlesource.com/new-password
All changes require a Change-ID tag in the commit message. A commit hook may be used to add this tag automatically, and can be found at: https://gerrit-review.googlesource.com/tools/hooks/commit-msg. To clone the repository and install the commit hook in one go:
git clone https://swiftshader.googlesource.com/SwiftShader && (cd SwiftShader && curl -Lo `git rev-parse --git-dir`/hooks/commit-msg https://gerrit-review.googlesource.com/tools/hooks/commit-msg ; chmod +x `git rev-parse --git-dir`/hooks/commit-msg)
Changes are uploaded to Gerrit by executing:
git push origin HEAD:refs/for/master
When ready, add a project owner as a reviewer on your change.
Some tests will automatically be run against the change. Notably, presubmit.sh verifies the change has been formatted using clang-format 10.0. Most IDEs come with clang-format support, but may require downgrading to clang-format version 10.0.
SwiftShader's OpenGL ES implementation can be tested using the dEQP test suite.
See docs/dEQP.md for details.
The third_party directory contains projects which originated outside of SwiftShader:
subzero contains a fork of the Subzero project. It is part of Google Chrome‘s (Portable) Native Client project. Its authoritative source is at https://chromium.googlesource.com/native_client/pnacl-subzero/. The fork was made using git-subtree to include all of Subzero’s history, and until further notice it should not diverge from the upstream project. Contributions must be tested using the README instructions, reviewed at https://chromium-review.googlesource.com, and then pulled into the SwiftShader repository.
llvm-subzero contains a minimized set of LLVM dependencies of the Subzero project.
PowerVR_SDK contains a subset of the PowerVR Graphics Native SDK for running several sample applications.
googletest contains the Google Test project, as a Git submodule. It is used for running unit tests for Chromium, and Reactor unit tests. Run git submodule update --init
to obtain/update the code. Any contributions should be made upstream.
See docs/Index.md.
Public mailing list: swiftshader@googlegroups.com
General bug tracker: https://g.co/swiftshaderbugs
Chrome specific bugs: https://bugs.chromium.org/p/swiftshader
The SwiftShader project is licensed under the Apache License Version 2.0. You can find a copy of it in LICENSE.txt.
Files in the third_party folder are subject to their respective license.
The legal authors for copyright purposes are listed in AUTHORS.txt.
CONTRIBUTORS.txt contains a list of names of individuals who have contributed to SwiftShader. If you‘re not on the list, but you’ve signed the Google CLA and have contributed more than a formatting change, feel free to request to be added.