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//
// Copyright (c) 2015 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.
//
// WorkaroundsGL.h: Workarounds for GL driver bugs and other issues.
#ifndef LIBANGLE_RENDERER_GL_WORKAROUNDSGL_H_
#define LIBANGLE_RENDERER_GL_WORKAROUNDSGL_H_
namespace rx
{
struct WorkaroundsGL
{
WorkaroundsGL()
: avoid1BitAlphaTextureFormats(false),
rgba4IsNotSupportedForColorRendering(false),
doesSRGBClearsOnLinearFramebufferAttachments(false),
doWhileGLSLCausesGPUHang(false),
finishDoesNotCauseQueriesToBeAvailable(false),
alwaysCallUseProgramAfterLink(false),
unpackOverlappingRowsSeparatelyUnpackBuffer(false),
emulateAbsIntFunction(false),
addAndTrueToLoopCondition(false),
emulateIsnanFloat(false),
useUnusedBlocksWithStandardOrSharedLayout(false),
dontRemoveInvariantForFragmentInput(false),
removeInvariantAndCentroidForESSL3(false)
{
}
// When writing a float to a normalized integer framebuffer, desktop OpenGL is allowed to write
// one of the two closest normalized integer representations (although round to nearest is
// preferred) (see section 2.3.5.2 of the GL 4.5 core specification). OpenGL ES requires that
// round-to-nearest is used (see "Conversion from Floating-Point to Framebuffer Fixed-Point" in
// section 2.1.2 of the OpenGL ES 2.0.25 spec). This issue only shows up on Intel and AMD
// drivers on framebuffer formats that have 1-bit alpha, work around this by using higher
// precision formats instead.
bool avoid1BitAlphaTextureFormats;
// On some older Intel drivers, GL_RGBA4 is not color renderable, glCheckFramebufferStatus
// returns GL_FRAMEBUFFER_UNSUPPORTED. Work around this by using a known color-renderable
// format.
bool rgba4IsNotSupportedForColorRendering;
// When clearing a framebuffer on Intel or AMD drivers, when GL_FRAMEBUFFER_SRGB is enabled, the
// driver clears to the linearized clear color despite the framebuffer not supporting SRGB
// blending. It only seems to do this when the framebuffer has only linear attachments, mixed
// attachments appear to get the correct clear color.
bool doesSRGBClearsOnLinearFramebufferAttachments;
// On Mac some GLSL constructs involving do-while loops cause GPU hangs, such as the following:
// int i = 1;
// do {
// i --;
// continue;
// } while (i > 0)
// Work around this by rewriting the do-while to use another GLSL construct (block + while)
bool doWhileGLSLCausesGPUHang;
// Calling glFinish doesn't cause all queries to report that the result is available on some
// (NVIDIA) drivers. It was found that enabling GL_DEBUG_OUTPUT_SYNCHRONOUS before the finish
// causes it to fully finish.
bool finishDoesNotCauseQueriesToBeAvailable;
// Always call useProgram after a successful link to avoid a driver bug.
// This workaround is meant to reproduce the use_current_program_after_successful_link
// workaround in Chromium (http://crbug.com/110263). It has been shown that this workaround is
// not necessary for MacOSX 10.9 and higher (http://crrev.com/39eb535b).
bool alwaysCallUseProgramAfterLink;
// In the case of unpacking from a pixel unpack buffer, unpack overlapping rows row by row.
bool unpackOverlappingRowsSeparatelyUnpackBuffer;
// In the case of packing to a pixel pack buffer, pack overlapping rows row by row.
bool packOverlappingRowsSeparatelyPackBuffer;
// During initialization, assign the current vertex attributes to the spec-mandated defaults.
bool initializeCurrentVertexAttributes;
// abs(i) where i is an integer returns unexpected result on Intel Mac.
// Emulate abs(i) with i * sign(i).
bool emulateAbsIntFunction;
// On Intel Mac, calculation of loop conditions in for and while loop has bug.
// Add "&& true" to the end of the condition expression to work around the bug.
bool addAndTrueToLoopCondition;
// When uploading textures from an unpack buffer, some drivers count an extra row padding when
// checking if the pixel unpack buffer is big enough. Tracking bug: http://anglebug.com/1512
// For example considering the pixel buffer below where in memory, each row data (D) of the
// texture is followed by some unused data (the dots):
// +-------+--+
// |DDDDDDD|..|
// |DDDDDDD|..|
// |DDDDDDD|..|
// |DDDDDDD|..|
// +-------A--B
// The last pixel read will be A, but the driver will think it is B, causing it to generate an
// error when the pixel buffer is just big enough.
bool unpackLastRowSeparatelyForPaddingInclusion;
// Equivalent workaround when uploading data from a pixel pack buffer.
bool packLastRowSeparatelyForPaddingInclusion;
// On some Intel drivers, using isnan() on highp float will get wrong answer. To work around
// this bug, we use an expression to emulate function isnan().
// Tracking bug: http://crbug.com/650547
bool emulateIsnanFloat;
// On Mac with OpenGL version 4.1, unused std140 or shared uniform blocks will be
// treated as inactive which is not consistent with WebGL2.0 spec. Reference all members in a
// unused std140 or shared uniform block at the beginning of main to work around it.
bool useUnusedBlocksWithStandardOrSharedLayout;
// This flag will keep invariant declaration for input in fragment shader for GLSL >=4.20
// on AMD.
bool dontRemoveInvariantForFragmentInput;
// This flag is used to fix spec difference between GLSL 4.1 or lower and ESSL3.
bool removeInvariantAndCentroidForESSL3;
};
}
#endif // LIBANGLE_RENDERER_GL_WORKAROUNDSGL_H_
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