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1 //
2 // Copyright 2015 The ANGLE Project Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style license that can be
4 // found in the LICENSE file.
5 //
6 
7 // FeaturesGL.h: Features and workarounds for GL driver bugs and other issues.
8 
9 #ifndef ANGLE_PLATFORM_FEATURESGL_H_
10 #define ANGLE_PLATFORM_FEATURESGL_H_
11 
12 #include "platform/Feature.h"
13 
14 namespace angle
15 {
16 
17 struct FeaturesGL : FeatureSetBase
18 {
19     FeaturesGL();
20     ~FeaturesGL();
21 
22     // When writing a float to a normalized integer framebuffer, desktop OpenGL is allowed to write
23     // one of the two closest normalized integer representations (although round to nearest is
24     // preferred) (see section 2.3.5.2 of the GL 4.5 core specification). OpenGL ES requires that
25     // round-to-nearest is used (see "Conversion from Floating-Point to Framebuffer Fixed-Point" in
26     // section 2.1.2 of the OpenGL ES 2.0.25 spec).  This issue only shows up on AMD drivers on
27     // framebuffer formats that have 1-bit alpha, work around this by using higher precision formats
28     // instead.
29     Feature avoid1BitAlphaTextureFormats = {"avoid_1_bit_alpha_texture_formats",
30                                             FeatureCategory::OpenGLWorkarounds,
31                                             "Issue with 1-bit alpha framebuffer formats", &members};
32 
33     // On some older Intel drivers, GL_RGBA4 is not color renderable, glCheckFramebufferStatus
34     // returns GL_FRAMEBUFFER_UNSUPPORTED. Work around this by using a known color-renderable
35     // format.
36     Feature rgba4IsNotSupportedForColorRendering = {"rgba4_is_not_supported_for_color_rendering",
37                                                     FeatureCategory::OpenGLWorkarounds,
38                                                     "GL_RGBA4 is not color renderable", &members};
39 
40     // Newer Intel GPUs natively support ETC2/EAC compressed texture formats.
41     Feature allowEtcFormats = {"allow_etc_formats", FeatureCategory::OpenGLWorkarounds,
42                                "Enable ETC2/EAC on desktop OpenGL", &members};
43 
44     // When clearing a framebuffer on Intel or AMD drivers, when GL_FRAMEBUFFER_SRGB is enabled, the
45     // driver clears to the linearized clear color despite the framebuffer not supporting SRGB
46     // blending.  It only seems to do this when the framebuffer has only linear attachments, mixed
47     // attachments appear to get the correct clear color.
48     Feature doesSRGBClearsOnLinearFramebufferAttachments = {
49         "does_srgb_clears_on_linear_framebuffer_attachments", FeatureCategory::OpenGLWorkarounds,
50         "Issue clearing framebuffers with linear attachments when GL_FRAMEBUFFER_SRGB is enabled",
51         &members};
52 
53     // On Mac some GLSL constructs involving do-while loops cause GPU hangs, such as the following:
54     //  int i = 1;
55     //  do {
56     //      i --;
57     //      continue;
58     //  } while (i > 0)
59     // Work around this by rewriting the do-while to use another GLSL construct (block + while)
60     Feature doWhileGLSLCausesGPUHang = {
61         "do_while_glsl_causes_gpu_hang", FeatureCategory::OpenGLWorkarounds,
62         "Some GLSL constructs involving do-while loops cause GPU hangs", &members,
63         "http://crbug.com/644669"};
64 
65     // On Mac AMD GPU gl_VertexID in GLSL vertex shader doesn't include base vertex value,
66     // Work aronud this by replace gl_VertexID with (gl_VertexID - angle_BaseVertex) when
67     // angle_BaseVertex is present.
68     Feature addBaseVertexToVertexID = {
69         "vertex_id_does_not_include_base_vertex", FeatureCategory::OpenGLWorkarounds,
70         "gl_VertexID in GLSL vertex shader doesn't include base vertex value", &members};
71 
72     // Calling glFinish doesn't cause all queries to report that the result is available on some
73     // (NVIDIA) drivers.  It was found that enabling GL_DEBUG_OUTPUT_SYNCHRONOUS before the finish
74     // causes it to fully finish.
75     Feature finishDoesNotCauseQueriesToBeAvailable = {
76         "finish_does_not_cause_queries_to_be_available", FeatureCategory::OpenGLWorkarounds,
77         "glFinish doesn't cause all queries to report available result", &members};
78 
79     // Always call useProgram after a successful link to avoid a driver bug.
80     // This workaround is meant to reproduce the use_current_program_after_successful_link
81     // workaround in Chromium (http://crbug.com/110263). It has been shown that this workaround is
82     // not necessary for MacOSX 10.9 and higher (http://crrev.com/39eb535b).
83     Feature alwaysCallUseProgramAfterLink = {
84         "always_call_use_program_after_link", FeatureCategory::OpenGLWorkarounds,
85         "Always call useProgram after a successful link to avoid a driver bug", &members,
86         "http://crbug.com/110263"};
87 
88     // On NVIDIA, in the case of unpacking from a pixel unpack buffer, unpack overlapping rows row
89     // by row.
90     Feature unpackOverlappingRowsSeparatelyUnpackBuffer = {
91         "unpack_overlapping_rows_separately_unpack_buffer", FeatureCategory::OpenGLWorkarounds,
92         "In the case of unpacking from a pixel unpack buffer, unpack overlapping rows row by row",
93         &members};
94 
95     // On NVIDIA, in the case of packing to a pixel pack buffer, pack overlapping rows row by row.
96     Feature packOverlappingRowsSeparatelyPackBuffer = {
97         "pack_overlapping_rows_separately_pack_buffer", FeatureCategory::OpenGLWorkarounds,
98         "In the case of packing to a pixel pack buffer, pack overlapping rows row by row",
99         &members};
100 
101     // On NVIDIA, during initialization, assign the current vertex attributes to the spec-mandated
102     // defaults.
103     Feature initializeCurrentVertexAttributes = {
104         "initialize_current_vertex_attributes", FeatureCategory::OpenGLWorkarounds,
105         "During initialization, assign the current vertex attributes to the spec-mandated defaults",
106         &members};
107 
108     // abs(i) where i is an integer returns unexpected result on Intel Mac.
109     // Emulate abs(i) with i * sign(i).
110     Feature emulateAbsIntFunction = {"emulate_abs_int_function", FeatureCategory::OpenGLWorkarounds,
111                                      "abs(i) where i is an integer returns unexpected result",
112                                      &members, "http://crbug.com/642227"};
113 
114     // On Intel Mac, calculation of loop conditions in for and while loop has bug.
115     // Add "&& true" to the end of the condition expression to work around the bug.
116     Feature addAndTrueToLoopCondition = {
117         "add_and_true_to_loop_condition", FeatureCategory::OpenGLWorkarounds,
118         "Calculation of loop conditions in for and while loop has bug", &members};
119 
120     // When uploading textures from an unpack buffer, some drivers count an extra row padding when
121     // checking if the pixel unpack buffer is big enough. Tracking bug: http://anglebug.com/1512
122     // For example considering the pixel buffer below where in memory, each row data (D) of the
123     // texture is followed by some unused data (the dots):
124     //     +-------+--+
125     //     |DDDDDDD|..|
126     //     |DDDDDDD|..|
127     //     |DDDDDDD|..|
128     //     |DDDDDDD|..|
129     //     +-------A--B
130     // The last pixel read will be A, but the driver will think it is B, causing it to generate an
131     // error when the pixel buffer is just big enough.
132     Feature unpackLastRowSeparatelyForPaddingInclusion = {
133         "unpack_last_row_separately_for_padding_inclusion", FeatureCategory::OpenGLWorkarounds,
134         "When uploading textures from an unpack buffer, some drivers count an extra row padding",
135         &members, "http://anglebug.com/1512"};
136 
137     // Equivalent workaround when uploading data from a pixel pack buffer.
138     Feature packLastRowSeparatelyForPaddingInclusion = {
139         "pack_last_row_separately_for_padding_inclusion", FeatureCategory::OpenGLWorkarounds,
140         "When uploading textures from an pack buffer, some drivers count an extra row padding",
141         &members, "http://anglebug.com/1512"};
142 
143     // On some Intel drivers, using isnan() on highp float will get wrong answer. To work around
144     // this bug, we use an expression to emulate function isnan().
145     // Tracking bug: http://crbug.com/650547
146     Feature emulateIsnanFloat = {"emulate_isnan_float", FeatureCategory::OpenGLWorkarounds,
147                                  "Using isnan() on highp float will get wrong answer", &members,
148                                  "http://crbug.com/650547"};
149 
150     // On Mac with OpenGL version 4.1, unused std140 or shared uniform blocks will be
151     // treated as inactive which is not consistent with WebGL2.0 spec. Reference all members in a
152     // unused std140 or shared uniform block at the beginning of main to work around it.
153     // Also used on Linux AMD.
154     Feature useUnusedBlocksWithStandardOrSharedLayout = {
155         "use_unused_blocks_with_standard_or_shared_layout", FeatureCategory::OpenGLWorkarounds,
156         "Unused std140 or shared uniform blocks will be treated as inactive", &members};
157 
158     // This flag is used to fix spec difference between GLSL 4.1 or lower and ESSL3.
159     Feature removeInvariantAndCentroidForESSL3 = {
160         "remove_invarient_and_centroid_for_essl3", FeatureCategory::OpenGLWorkarounds,
161         "Fix spec difference between GLSL 4.1 or lower and ESSL3", &members};
162 
163     // On Intel Mac OSX 10.11 driver, using "-float" will get wrong answer. Use "0.0 - float" to
164     // replace "-float".
165     // Tracking bug: http://crbug.com/308366
166     Feature rewriteFloatUnaryMinusOperator = {
167         "rewrite_float_unary_minus_operator", FeatureCategory::OpenGLWorkarounds,
168         "Using '-<float>' will get wrong answer", &members, "http://crbug.com/308366"};
169 
170     // On NVIDIA drivers, atan(y, x) may return a wrong answer.
171     // Tracking bug: http://crbug.com/672380
172     Feature emulateAtan2Float = {"emulate_atan_2_float", FeatureCategory::OpenGLWorkarounds,
173                                  "atan(y, x) may return a wrong answer", &members,
174                                  "http://crbug.com/672380"};
175 
176     // Some drivers seem to forget about UBO bindings when using program binaries. Work around
177     // this by re-applying the bindings after the program binary is loaded or saved.
178     // This only seems to affect AMD OpenGL drivers, and some Android devices.
179     // http://anglebug.com/1637
180     Feature reapplyUBOBindingsAfterUsingBinaryProgram = {
181         "reapply_ubo_bindings_after_using_binary_program", FeatureCategory::OpenGLWorkarounds,
182         "Some drivers forget about UBO bindings when using program binaries", &members,
183         "http://anglebug.com/1637"};
184 
185     // Some Linux OpenGL drivers return 0 when we query MAX_VERTEX_ATTRIB_STRIDE in an OpenGL 4.4 or
186     // higher context.
187     // This only seems to affect AMD OpenGL drivers.
188     // Tracking bug: http://anglebug.com/1936
189     Feature emulateMaxVertexAttribStride = {
190         "emulate_max_vertex_attrib_stride", FeatureCategory::OpenGLWorkarounds,
191         "Some drivers return 0 when MAX_VERTEX_ATTRIB_STRIED queried", &members,
192         "http://anglebug.com/1936"};
193 
194     // Initializing uninitialized locals caused odd behavior on Android Qualcomm in a few WebGL 2
195     // tests. Tracking bug: http://anglebug.com/2046
196     Feature dontInitializeUninitializedLocals = {
197         "dont_initialize_uninitialized_locals", FeatureCategory::OpenGLWorkarounds,
198         "Initializing uninitialized locals caused odd behavior in a few WebGL 2 tests", &members,
199         "http://anglebug.com/2046"};
200 
201     // On some NVIDIA drivers the point size range reported from the API is inconsistent with the
202     // actual behavior. Clamp the point size to the value from the API to fix this.
203     Feature clampPointSize = {
204         "clamp_point_size", FeatureCategory::OpenGLWorkarounds,
205         "The point size range reported from the API is inconsistent with the actual behavior",
206         &members};
207 
208     // On some NVIDIA drivers certain types of GLSL arithmetic ops mixing vectors and scalars may be
209     // executed incorrectly. Change them in the shader translator. Tracking bug:
210     // http://crbug.com/772651
211     Feature rewriteVectorScalarArithmetic = {"rewrite_vector_scalar_arithmetic",
212                                              FeatureCategory::OpenGLWorkarounds,
213                                              "Certain types of GLSL arithmetic ops mixing vectors "
214                                              "and scalars may be executed incorrectly",
215                                              &members, "http://crbug.com/772651"};
216 
217     // On some Android devices for loops used to initialize variables hit native GLSL compiler bugs.
218     Feature dontUseLoopsToInitializeVariables = {
219         "dont_use_loops_to_initialize_variables", FeatureCategory::OpenGLWorkarounds,
220         "For loops used to initialize variables hit native GLSL compiler bugs", &members,
221         "http://crbug.com/809422"};
222 
223     // On some NVIDIA drivers gl_FragDepth is not clamped correctly when rendering to a floating
224     // point depth buffer. Clamp it in the translated shader to fix this.
225     Feature clampFragDepth = {
226         "clamp_frag_depth", FeatureCategory::OpenGLWorkarounds,
227         "gl_FragDepth is not clamped correctly when rendering to a floating point depth buffer",
228         &members};
229 
230     // On some NVIDIA drivers before version 397.31 repeated assignment to swizzled values inside a
231     // GLSL user-defined function have incorrect results. Rewrite this type of statements to fix
232     // this.
233     Feature rewriteRepeatedAssignToSwizzled = {"rewrite_repeated_assign_to_swizzled",
234                                                FeatureCategory::OpenGLWorkarounds,
235                                                "Repeated assignment to swizzled values inside a "
236                                                "GLSL user-defined function have incorrect results",
237                                                &members};
238 
239     // On some AMD and Intel GL drivers ARB_blend_func_extended does not pass the tests.
240     // It might be possible to work around the Intel bug by rewriting *FragData to *FragColor
241     // instead of disabling the functionality entirely. The AMD bug looked like incorrect blending,
242     // not sure if a workaround is feasible. http://anglebug.com/1085
243     Feature disableBlendFuncExtended = {
244         "disable_blend_func_extended", FeatureCategory::OpenGLWorkarounds,
245         "ARB_blend_func_extended does not pass the tests", &members, "http://anglebug.com/1085"};
246 
247     // Qualcomm drivers returns raw sRGB values instead of linearized values when calling
248     // glReadPixels on unsized sRGB texture formats. http://crbug.com/550292 and
249     // http://crbug.com/565179
250     Feature unsizedsRGBReadPixelsDoesntTransform = {
251         "unsized_srgb_read_pixels_doesnt_transform", FeatureCategory::OpenGLWorkarounds,
252         "Drivers returning raw sRGB values instead of linearized values when calling glReadPixels "
253         "on unsized sRGB texture formats",
254         &members, "http://crbug.com/565179"};
255 
256     // Older Qualcomm drivers generate errors when querying the number of bits in timer queries, ex:
257     // GetQueryivEXT(GL_TIME_ELAPSED, GL_QUERY_COUNTER_BITS).  http://anglebug.com/3027
258     Feature queryCounterBitsGeneratesErrors = {
259         "query_counter_bits_generates_errors", FeatureCategory::OpenGLWorkarounds,
260         "Drivers generate errors when querying the number of bits in timer queries", &members,
261         "http://anglebug.com/3027"};
262 
263     // Re-linking a program in parallel is buggy on some Intel Windows OpenGL drivers and Android
264     // platforms.
265     // http://anglebug.com/3045
266     Feature dontRelinkProgramsInParallel = {
267         "dont_relink_programs_in_parallel", FeatureCategory::OpenGLWorkarounds,
268         "Relinking a program in parallel is buggy", &members, "http://anglebug.com/3045"};
269 
270     // Some tests have been seen to fail using worker contexts, this switch allows worker contexts
271     // to be disabled for some platforms. http://crbug.com/849576
272     Feature disableWorkerContexts = {"disable_worker_contexts", FeatureCategory::OpenGLWorkarounds,
273                                      "Some tests have been seen to fail using worker contexts",
274                                      &members, "http://crbug.com/849576"};
275 
276     // Most Android devices fail to allocate a texture that is larger than 4096. Limit the caps
277     // instead of generating GL_OUT_OF_MEMORY errors. Also causes system to hang on some older
278     // intel mesa drivers on Linux.
279     Feature limitMaxTextureSizeTo4096 = {"max_texture_size_limit_4096",
280                                          FeatureCategory::OpenGLWorkarounds,
281                                          "Limit max texture size to 4096 to avoid frequent "
282                                          "out-of-memory errors",
283                                          &members, "http://crbug.com/927470"};
284 
285     // Prevent excessive MSAA allocations on Android devices, various rendering bugs have been
286     // observed and they tend to be high DPI anyways. http://crbug.com/797243
287     Feature limitMaxMSAASamplesTo4 = {
288         "max_msaa_sample_count_4", FeatureCategory::OpenGLWorkarounds,
289         "Various rendering bugs have been observed when using higher MSAA counts", &members,
290         "http://crbug.com/797243"};
291 
292     // Prefer to do the robust resource init clear using a glClear. Calls to TexSubImage2D on large
293     // textures can take hundreds of milliseconds because of slow uploads on macOS. Do this only on
294     // macOS because clears are buggy on other drivers.
295     // https://crbug.com/848952 (slow uploads on macOS)
296     // https://crbug.com/883276 (buggy clears on Android)
297     Feature allowClearForRobustResourceInit = {
298         "allow_clear_for_robust_resource_init", FeatureCategory::OpenGLWorkarounds,
299         "Using glClear for robust resource initialization is buggy on some drivers and leads to "
300         "texture corruption. Default to data uploads except on MacOS where it is very slow.",
301         &members, "http://crbug.com/883276"};
302 
303     // Some drivers automatically handle out-of-bounds uniform array access but others need manual
304     // clamping to satisfy the WebGL requirements.
305     Feature clampArrayAccess = {"clamp_array_access", FeatureCategory::OpenGLWorkarounds,
306                                 "Clamp uniform array access to avoid reading invalid memory.",
307                                 &members, "http://anglebug.com/2978"};
308 
309     // Reset glTexImage2D base level to workaround pixel comparison failure above Mac OS 10.12.4 on
310     // Intel Mac.
311     Feature resetTexImage2DBaseLevel = {"reset_teximage2d_base_level",
312                                         FeatureCategory::OpenGLWorkarounds,
313                                         "Reset texture base level before calling glTexImage2D to "
314                                         "work around pixel comparison failure.",
315                                         &members, "https://crbug.com/705865"};
316 
317     // glClearColor does not always work on Intel 6xxx Mac drivers when the clear color made up of
318     // all zeros and ones.
319     Feature clearToZeroOrOneBroken = {
320         "clear_to_zero_or_one_broken", FeatureCategory::OpenGLWorkarounds,
321         "Clears when the clear color is all zeros or ones do not work.", &members,
322         "https://crbug.com/710443"};
323 
324     // Some older Linux Intel mesa drivers will hang the system when allocating large textures. Fix
325     // this by capping the max texture size.
326     Feature limitMax3dArrayTextureSizeTo1024 = {
327         "max_3d_array_texture_size_1024", FeatureCategory::OpenGLWorkarounds,
328         "Limit max 3d texture size and max array texture layers to 1024 to avoid system hang",
329         &members, "http://crbug.com/927470"};
330 
331     // BlitFramebuffer has issues on some platforms with large source/dest texture sizes. This
332     // workaround adjusts the destination rectangle source and dest rectangle to fit within maximum
333     // twice the size of the framebuffer.
334     Feature adjustSrcDstRegionBlitFramebuffer = {
335         "adjust_src_dst_region_for_blitframebuffer", FeatureCategory::OpenGLWorkarounds,
336         "Many platforms have issues with blitFramebuffer when the parameters are large.", &members,
337         "http://crbug.com/830046"};
338 
339     // BlitFramebuffer has issues on Mac when the source bounds aren't enclosed by the framebuffer.
340     // This workaround clips the source region and adjust the dest region proportionally.
341     Feature clipSrcRegionBlitFramebuffer = {
342         "clip_src_region_for_blitframebuffer", FeatureCategory::OpenGLWorkarounds,
343         "Issues with blitFramebuffer when the parameters don't match the framebuffer size.",
344         &members, "http://crbug.com/830046"};
345 
346     // Mac Intel samples transparent black from GL_COMPRESSED_RGB_S3TC_DXT1_EXT
347     Feature rgbDXT1TexturesSampleZeroAlpha = {
348         "rgb_dxt1_textures_sample_zero_alpha", FeatureCategory::OpenGLWorkarounds,
349         "Sampling BLACK texels from RGB DXT1 textures returns transparent black on Mac.", &members,
350         "http://anglebug.com/3729"};
351 
352     // Mac incorrectly executes both sides of && and || expressions when they should short-circuit.
353     Feature unfoldShortCircuits = {
354         "unfold_short_circuits", FeatureCategory::OpenGLWorkarounds,
355         "Mac incorrectly executes both sides of && and || expressions when they should "
356         "short-circuit.",
357         &members, "http://anglebug.com/482"};
358 
359     Feature emulatePrimitiveRestartFixedIndex = {
360         "emulate_primitive_restart_fixed_index", FeatureCategory::OpenGLWorkarounds,
361         "When GL_PRIMITIVE_RESTART_FIXED_INDEX is not available, emulate it with "
362         "GL_PRIMITIVE_RESTART and glPrimitiveRestartIndex.",
363         &members, "http://anglebug.com/3997"};
364 
365     Feature setPrimitiveRestartFixedIndexForDrawArrays = {
366         "set_primitive_restart_fixed_index_for_draw_arrays", FeatureCategory::OpenGLWorkarounds,
367         "Some drivers discard vertex data in DrawArrays calls when the fixed primitive restart "
368         "index is within the number of primitives being drawn.",
369         &members, "http://anglebug.com/3997"};
370 
371     // Dynamic indexing of swizzled l-values doesn't work correctly on various platforms.
372     Feature removeDynamicIndexingOfSwizzledVector = {
373         "remove_dynamic_indexing_of_swizzled_vector", FeatureCategory::OpenGLWorkarounds,
374         "Dynamic indexing of swizzled l-values doesn't work correctly on various platforms.",
375         &members, "http://crbug.com/709351"};
376 
377     // Intel Mac drivers does not treat texelFetchOffset() correctly.
378     Feature preAddTexelFetchOffsets = {
379         "pre_add_texel_fetch_offsets", FeatureCategory::OpenGLWorkarounds,
380         "Intel Mac drivers mistakenly consider the parameter position of nagative vaule as invalid "
381         "even if the sum of position and offset is in range, so we need to add workarounds by "
382         "rewriting texelFetchOffset(sampler, position, lod, offset) into texelFetch(sampler, "
383         "position + offset, lod).",
384         &members, "http://crbug.com/642605"};
385 
386     // All Mac drivers do not handle struct scopes correctly. This workaround overwrites a struct
387     // name with a unique prefix
388     Feature regenerateStructNames = {
389         "regenerate_struct_names", FeatureCategory::OpenGLWorkarounds,
390         "All Mac drivers do not handle struct scopes correctly. This workaround overwrites a struct"
391         "name with a unique prefix.",
392         &members, "http://crbug.com/403957"};
393 
394     // Quite some OpenGL ES drivers don't implement readPixels for RGBA/UNSIGNED_SHORT from
395     // EXT_texture_norm16 correctly
396     Feature readPixelsUsingImplementationColorReadFormatForNorm16 = {
397         "read_pixels_using_implementation_color_read_format", FeatureCategory::OpenGLWorkarounds,
398         "Quite some OpenGL ES drivers don't implement readPixels for RGBA/UNSIGNED_SHORT from "
399         "EXT_texture_norm16 correctly",
400         &members, "http://anglebug.com/4214"};
401 
402     // Bugs exist in some Intel drivers where dependencies are incorrectly
403     // tracked for textures which are copy destinations (via CopyTexImage2D, for
404     // example). Flush before DeleteTexture if these entry points have been
405     // called recently.
406     Feature flushBeforeDeleteTextureIfCopiedTo = {
407         "flush_before_delete_texture_if_copied_to", FeatureCategory::OpenGLWorkarounds,
408         "Some drivers track CopyTex{Sub}Image texture dependencies incorrectly. Flush"
409         " before glDeleteTextures in this case",
410         &members, "http://anglebug.com/4267"};
411 
412     // Rewrite row-major matrices as column-major as a driver bug workaround if
413     // necessary.
414     Feature rewriteRowMajorMatrices = {
415         "rewrite_row_major_matrices", FeatureCategory::OpenGLWorkarounds,
416         "Rewrite row major matrices in shaders as column major as a driver bug workaround",
417         &members, "http://anglebug.com/2273"};
418 
419     // Bugs exist in various OpenGL Intel drivers on Windows that produce incorrect
420     // values for GL_COMPRESSED_SRGB_S3TC_DXT1_EXT format. Replace it with
421     // GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT as it's the closest option allowed by
422     // the WebGL extension spec.
423     Feature avoidDXT1sRGBTextureFormat = {
424         "avoid_dxt1_srgb_texture_format", FeatureCategory::OpenGLWorkarounds,
425         "Replaces DXT1 sRGB with DXT1 sRGB Alpha as a driver bug workaround.", &members};
426 
427     // Bugs exist in OpenGL AMD drivers on Windows that produce incorrect pipeline state for
428     // colorMaski calls.
429     Feature disableDrawBuffersIndexed = {"disable_draw_buffers_indexed",
430                                          FeatureCategory::OpenGLWorkarounds,
431                                          "Disable OES_draw_buffers_indexed extension.", &members};
432 
433     // GL_EXT_semaphore_fd doesn't work properly with Mesa 19.3.4 and earlier versions.
434     Feature disableSemaphoreFd = {"disable_semaphore_fd", FeatureCategory::OpenGLWorkarounds,
435                                   "Disable GL_EXT_semaphore_fd extension", &members,
436                                   "https://crbug.com/1046462"};
437 
438     // GL_EXT_disjoint_timer_query doesn't work properly with Linux VMWare drivers.
439     Feature disableTimestampQueries = {
440         "disable_timestamp_queries", FeatureCategory::OpenGLWorkarounds,
441         "Disable GL_EXT_disjoint_timer_query extension", &members, "https://crbug.com/811661"};
442 
443     // Some drivers use linear blending when generating mipmaps for sRGB textures. Work around this
444     // by generating mipmaps in a linear texture and copying back to sRGB.
445     Feature encodeAndDecodeSRGBForGenerateMipmap = {
446         "decode_encode_srgb_for_generatemipmap", FeatureCategory::OpenGLWorkarounds,
447         "Decode and encode before generateMipmap for srgb format textures.", &members,
448         "http://anglebug.com/4646"};
449 
450     Feature emulateCopyTexImage2DFromRenderbuffers = {
451         "emulate_copyteximage2d_from_renderbuffers", FeatureCategory::OpenGLWorkarounds,
452         "CopyTexImage2D spuriously returns errors on iOS when copying from renderbuffers.",
453         &members, "https://anglebug.com/4674"};
454 
455     Feature disableGPUSwitchingSupport = {
456         "disable_gpu_switching_support", FeatureCategory::OpenGLWorkarounds,
457         "Disable GPU switching support (use only the low-power GPU) on older MacBook Pros.",
458         &members, "https://crbug.com/1091824"};
459 
460     // KHR_parallel_shader_compile fails TSAN on Linux, so we avoid using it with this workaround.
461     Feature disableNativeParallelCompile = {
462         "disable_native_parallel_compile", FeatureCategory::OpenGLWorkarounds,
463         "Do not use native KHR_parallel_shader_compile even when available.", &members,
464         "http://crbug.com/1094869"};
465 
466     Feature emulatePackSkipRowsAndPackSkipPixels = {
467         "emulate_pack_skip_rows_and_pack_skip_pixels", FeatureCategory::OpenGLWorkarounds,
468         "GL_PACK_SKIP_ROWS and GL_PACK_SKIP_PIXELS are ignored in Apple's OpenGL driver.", &members,
469         "https://anglebug.com/4849"};
470 
471     // Some drivers return bogus/1hz values for GetMscRate, which we may want to clamp
472     Feature clampMscRate = {
473         "clamp_msc_rate", FeatureCategory::OpenGLWorkarounds,
474         "Some drivers return bogus values for GetMscRate, so we clamp it to 30Hz", &members,
475         "https://crbug.com/1042393"};
476 
477     // Mac drivers generate GL_INVALID_VALUE when binding a transform feedback buffer with
478     // glBindBufferRange before first binding it to some generic binding point.
479     Feature bindTransformFeedbackBufferBeforeBindBufferRange = {
480         "bind_transform_feedback_buffer_before_bind_buffer_range",
481         FeatureCategory::OpenGLWorkarounds,
482         "Bind transform feedback buffers to the generic binding point before calling "
483         "glBindBufferBase or glBindBufferRange.",
484         &members, "https://anglebug.com/5140"};
485 
486     // Speculative fix for issues on Linux/Wayland where exposing GLX_OML_sync_control renders
487     // Chrome unusable
488     Feature disableSyncControlSupport = {
489         "disable_sync_control_support", FeatureCategory::OpenGLWorkarounds,
490         "Speculative fix for issues on Linux/Wayland where exposing GLX_OML_sync_control renders "
491         "Chrome unusable",
492         &members, "https://crbug.com/1137851"};
493 
494     // Buffers need to maintain a shadow copy of data when buffer data readback is not possible
495     // through the GL API
496     Feature keepBufferShadowCopy = {
497         "keep_buffer_shadow_copy", FeatureCategory::OpenGLWorkarounds,
498         "Maintain a shadow copy of buffer data when the GL API does not permit reading data back.",
499         &members};
500 
501     // glGenerateMipmap fails if the zero texture level is not set on some Mac drivers
502     Feature setZeroLevelBeforeGenerateMipmap = {
503         "set_zero_level_before_generating_mipmap", FeatureCategory::OpenGLWorkarounds,
504         "glGenerateMipmap fails if the zero texture level is not set on some Mac drivers.",
505         &members};
506 
507     // On macOS with AMD GPUs, packed color formats like RGB565 and RGBA4444 are buggy. Promote them
508     // to 8 bit per channel formats.
509     Feature promotePackedFormatsTo8BitPerChannel = {
510         "promote_packed_formats_to_8_bit_per_channel", FeatureCategory::OpenGLWorkarounds,
511         "Packed color formats are buggy on Macs with AMD GPUs", &members,
512         "http://anglebug.com/5469"};
513 
514     // If gl_FragColor is not written by fragment shader, it may cause context lost with Adreno 42x
515     // and 3xx.
516     Feature initFragmentOutputVariables = {
517         "init_fragment_output_variables", FeatureCategory::OpenGLWorkarounds,
518         "No init gl_FragColor causes context lost", &members, "http://crbug.com/1171371"};
519 
520     // On macOS with Intel GPUs, instanced array with divisor > 0 is buggy when first > 0 in
521     // drawArraysInstanced. Shift the attributes with extra offset to workaround.
522     Feature shiftInstancedArrayDataWithExtraOffset = {
523         "shift_instanced_array_data_with_offset", FeatureCategory::OpenGLWorkarounds,
524         "glDrawArraysInstanced is buggy on certain new Mac Intel GPUs", &members,
525         "http://crbug.com/1144207"};
526 
527     // ANGLE needs to support devices that have no native VAOs. Sync everything to the default VAO.
528     Feature syncVertexArraysToDefault = {
529         "sync_vertex_arrays_to_default", FeatureCategory::OpenGLWorkarounds,
530         "Only use the default VAO because of missing support or driver bugs", &members,
531         "http://anglebug.com/5577"};
532 
533     // On desktop Linux/AMD when using the amdgpu drivers, the precise kernel and DRM version are
534     // leaked via GL_RENDERER. We workaround this to improve user privacy.
535     Feature sanitizeAmdGpuRendererString = {
536         "sanitize_amdgpu_renderer_string", FeatureCategory::OpenGLWorkarounds,
537         "Strip precise kernel and DRM version information from amdgpu renderer strings.", &members,
538         "http://crbug.com/1181193"};
539 
540     // Imagination GL drivers are buggy with context switching. We need to ubind fbo to workaround a
541     // crash in the driver.
542     Feature unbindFBOOnContextSwitch = {"unbind_fbo_before_switching_context",
543                                         FeatureCategory::OpenGLWorkarounds,
544                                         "Imagination GL drivers are buggy with context switching.",
545                                         &members, "http://crbug.com/1181193"};
546 
547     Feature flushOnFramebufferChange = {"flush_on_framebuffer_change",
548                                         FeatureCategory::OpenGLWorkarounds,
549                                         "Switching framebuffers without a flush can lead to "
550                                         "crashes on Intel 9th Generation GPU Macs.",
551                                         &members, "http://crbug.com/1181068"};
552 
553     Feature disableMultisampledRenderToTexture = {
554         "disable_mutlisampled_render_to_texture", FeatureCategory::OpenGLWorkarounds,
555         "Many drivers have bugs when using GL_EXT_multisampled_render_to_texture", &members,
556         "http://anglebug.com/2894"};
557 
558     // Mac OpenGL drivers often hang when calling glTexSubImage with >120kb of data. Instead, upload
559     // the data in <120kb chunks.
560     static constexpr const size_t kUploadTextureDataInChunksUploadSize = (120 * 1024) - 1;
561     Feature uploadTextureDataInChunks                                  = {
562         "chunked_texture_upload", FeatureCategory::OpenGLWorkarounds,
563         "Upload texture data in <120kb chunks to work around Mac driver hangs and crashes.",
564         &members, "http://crbug.com/1181068"};
565 };
566 
567 inline FeaturesGL::FeaturesGL()  = default;
568 inline FeaturesGL::~FeaturesGL() = default;
569 
570 }  // namespace angle
571 
572 #endif  // ANGLE_PLATFORM_FEATURESGL_H_
573