kc3-lang/angle/src/compiler/translator/tree_ops/vulkan/EmulateDithering.h

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• Hash : 665ddccd
  Author :
  Date : 2021-12-09T23:06:39
  

  Vulkan: Emulate dithering
  
  Dithering in OpenGL is vaguely defined, to the extent that no dithering
  is also a valid dithering algorithm.  Dithering is enabled by default,
  but emulating it has a non-negligible cost.  Similarly to some other
  GLES drivers, ANGLE enables dithering only on low-bit formats where
  visual banding is particularly common; namely RGBA4444, RGBA5551 and
  RGB565.
  
  Dithering is emulated in the fragment shader and is controlled by a spec
  constant.  Every 2 bits of the spec constant correspond to one
  attachment, with the value indicating:
  
  - 00: No dithering
  - 01: Dither for RGBA4444
  - 10: Dither for RGBA5551
  - 11: Dither for RGB565
  
  The translator appends code to the shader that, based on the format
  specified by the specialization constant, adds dithering to each color
  attachment output.  A 2x2 Bayer matrix is used for dithering, indexed by
  gl_FragCoord.xy % 2.
  
  Bug: angleproject:6755
  Change-Id: Ib45da5938e299b6626bff921119d63e7357dd353
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3374261
  Reviewed-by: Tim Van Patten <timvp@google.com>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  

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• src/compiler/translator/tree_ops/vulkan/EmulateDithering.h

• //
  // Copyright 2022 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // EmulateDithering: Adds dithering code to fragment shader outputs based on a specialization
  // constant control value.
  //
  
  #ifndef COMPILER_TRANSLATOR_TREEOPS_VULKAN_EMULATEDITHERING_H_
  #define COMPILER_TRANSLATOR_TREEOPS_VULKAN_EMULATEDITHERING_H_
  
  #include "common/angleutils.h"
  
  namespace sh
  {
  class TCompiler;
  class TIntermBlock;
  class TSymbolTable;
  class SpecConst;
  class DriverUniform;
  
  ANGLE_NO_DISCARD bool EmulateDithering(TCompiler *compiler,
                                         TIntermBlock *root,
                                         TSymbolTable *symbolTable,
                                         SpecConst *specConst,
                                         DriverUniform *driverUniforms);
  }  // namespace sh
  
  #endif  // COMPILER_TRANSLATOR_TREEOPS_VULKAN_EMULATEDITHERING_H_
  

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