Hash :
93560ef5
        
        Author :
  
        
        Date :
2019-07-25T16:13:02
        
      
Vulkan: Seamful cube map emulation In GLSL, a cube texture is sampled with one of textureCube* functions. This function takes a 3D coordinate which is a vector from the center of the cube and identifies a direction to sample from. GLES2.0 has the following table that translates this 3D coordinate (Rx, Ry, Rz) to a face and ST coordinates within that face. This table can be found in Section 3.7.5 (Cube Map Texture Selection). A compiler pass is implemented in ANGLE that replaces samplerCube declarations with a sampler2DArray. The textureCube* functions are replaced with the corresponding texture* functions with the translated coordinates according to that table. Gradients provided to textureCubeGrad are translated using the same formulae, which is not precise but the spec specifies this projection to be implementation dependent. Helper invocations enabled through WQM (whole quad mode) cause a nuisance in that the extrapolated varyings used as coordinates in a textureCube call could have a different major axis (and therefore face) from the non-helper invocations that lie within the geometry. subgroupQuadSwap* operations are used in conjunction with gl_HelperInvocation to make sure the helper threads calculate texture UVs in the same face as the non-helper invocations. Bug: angleproject:3300 Bug: angleproject:3240 Bug: angleproject:3243 Bug: angleproject:3732 Change-Id: I0cb6a9b1f2e1e6a392b5baca1c7118ed1c502ccf Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1715977 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
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//
// Copyright 2018 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.
//
// FeaturesVk.h: Optional features for the Vulkan renderer.
//
#ifndef ANGLE_PLATFORM_FEATURESVK_H_
#define ANGLE_PLATFORM_FEATURESVK_H_
#include "platform/Feature.h"
namespace angle
{
struct FeaturesVk : FeatureSetBase
{
    FeaturesVk();
    ~FeaturesVk();
    // Line segment rasterization must follow OpenGL rules. This means using an algorithm similar
    // to Bresenham's. Vulkan uses a different algorithm. This feature enables the use of pixel
    // shader patching to implement OpenGL basic line rasterization rules. This feature will
    // normally always be enabled. Exposing it as an option enables performance testing.
    Feature basicGLLineRasterization = {
        "basic_gl_line_rasterization", FeatureCategory::VulkanFeatures,
        "Enable the use of pixel shader patching to implement OpenGL basic line "
        "rasterization rules",
        &members};
    // Flips the viewport to render upside-down. This has the effect to render the same way as
    // OpenGL. If this feature gets enabled, we enable the KHR_MAINTENANCE_1 extension to allow
    // negative viewports. We inverse rendering to the backbuffer by reversing the height of the
    // viewport and increasing Y by the height. So if the viewport was (0,0,width,height), it
    // becomes (0, height, width, -height). Unfortunately, when we start doing this, we also need
    // to adjust a lot of places since the rendering now happens upside-down. Affected places so
    // far:
    // -readPixels
    // -copyTexImage
    // -framebuffer blit
    // -generating mipmaps
    // -Point sprites tests
    // -texStorage
    Feature flipViewportY = {"flip_viewport_y", FeatureCategory::VulkanFeatures,
                             "Flips the viewport to render upside-down", &members};
    // Add an extra copy region when using vkCmdCopyBuffer as the Windows Intel driver seems
    // to have a bug where the last region is ignored.
    Feature extraCopyBufferRegion = {
        "extra_copy_buffer_region", FeatureCategory::VulkanWorkarounds,
        "Windows Intel driver seems to have a bug where the last copy region in "
        "vkCmdCopyBuffer is ignored",
        &members};
    // This flag is added for the sole purpose of end2end tests, to test the correctness
    // of various algorithms when a fallback format is used, such as using a packed format to
    // emulate a depth- or stencil-only format.
    Feature forceFallbackFormat = {"force_fallback_format", FeatureCategory::VulkanWorkarounds,
                                   "Force a fallback format for angle_end2end_tests", &members};
    // On some NVIDIA drivers the point size range reported from the API is inconsistent with the
    // actual behavior. Clamp the point size to the value from the API to fix this.
    // Tracked in http://anglebug.com/2970.
    Feature clampPointSize = {
        "clamp_point_size", FeatureCategory::VulkanWorkarounds,
        "On some NVIDIA drivers, the point size range reported from the API is "
        "inconsistent with the actual behavior",
        &members, "http://anglebug.com/2970"};
    // On some android devices, the memory barrier between the compute shader that converts vertex
    // attributes and the vertex shader that reads from it is ineffective.  Only known workaround is
    // to perform a flush after the conversion.  http://anglebug.com/3016
    Feature flushAfterVertexConversion = {
        "flush_after_vertex_conversion", FeatureCategory::VulkanWorkarounds,
        "On some android devices, the memory barrier between the compute shader that converts "
        "vertex attributes and the vertex shader that reads from it is ineffective",
        &members, "http://anglebug.com/3016"};
    // Whether the VkDevice supports the VK_KHR_incremental_present extension, on which the
    // EGL_KHR_swap_buffers_with_damage extension can be layered.
    Feature supportsIncrementalPresent = {
        "supports_incremental_present", FeatureCategory::VulkanFeatures,
        "VkDevice supports the VK_KHR_incremental_present extension", &members};
    // Whether texture copies on cube map targets should be done on GPU.  This is a workaround for
    // Intel drivers on windows that have an issue with creating single-layer views on cube map
    // textures.
    Feature forceCpuPathForCubeMapCopy = {
        "force_cpu_path_for_cube_map_copy", FeatureCategory::VulkanWorkarounds,
        "Some Intel Windows drivers have an issue with creating single-layer "
        "views on cube map textures",
        &members};
    // Whether the VkDevice supports the VK_ANDROID_external_memory_android_hardware_buffer
    // extension, on which the EGL_ANDROID_image_native_buffer extension can be layered.
    Feature supportsAndroidHardwareBuffer = {
        "supports_android_hardware_buffer", FeatureCategory::VulkanFeatures,
        "VkDevice supports the VK_ANDROID_external_memory_android_hardware_buffer extension",
        &members};
    // Whether the VkDevice supports the VK_KHR_external_memory_fd extension, on which the
    // GL_EXT_memory_object_fd extension can be layered.
    Feature supportsExternalMemoryFd = {
        "supports_external_memory_fd", FeatureCategory::VulkanFeatures,
        "VkDevice supports the VK_KHR_external_memory_fd extension", &members};
    // Whether the VkDevice supports the VK_KHR_external_semaphore_fd extension, on which the
    // GL_EXT_semaphore_fd extension can be layered.
    Feature supportsExternalSemaphoreFd = {
        "supports_external_semaphore_fd", FeatureCategory::VulkanFeatures,
        "VkDevice supports the VK_KHR_external_semaphore_fd extension", &members};
    // Whether the VkDevice supports the VK_EXT_shader_stencil_export extension, which is used to
    // perform multisampled resolve of stencil buffer.  A multi-step workaround is used instead if
    // this extension is not available.
    Feature supportsShaderStencilExport = {
        "supports_shader_stencil_export", FeatureCategory::VulkanFeatures,
        "VkDevice supports the VK_EXT_shader_stencil_export extension", &members};
    // Where VK_EXT_transform_feedback is not support, an emulation path is used.
    // http://anglebug.com/3205
    Feature emulateTransformFeedback = {
        "emulate_transform_feedback", FeatureCategory::VulkanFeatures,
        "Emulate transform feedback as the VK_EXT_transform_feedback is not present.", &members,
        "http://anglebug.com/3205"};
    // VK_PRESENT_MODE_FIFO_KHR causes random timeouts on Linux Intel. http://anglebug.com/3153
    Feature disableFifoPresentMode = {
        "disable_fifo_present_mode", FeatureCategory::VulkanWorkarounds,
        "On Linux Intel, VK_PRESENT_MODE_FIFO_KHR causes random timeouts", &members,
        "http://anglebug.com/3153"};
    // On Qualcomm, a bug is preventing us from using loadOp=Clear with inline commands in the
    // render pass.  http://anglebug.com/2361
    Feature restartRenderPassAfterLoadOpClear = {
        "restart_render_pass_after_load_op_clear", FeatureCategory::VulkanWorkarounds,
        "On Qualcomm, a bug is preventing us from using loadOp=Clear with inline "
        "commands in the render pass",
        &members, "http://anglebug.com/2361"};
    // On Qualcomm, gaps in bound descriptor set indices causes the post-gap sets to misbehave.
    // For example, binding only descriptor set 3 results in zero being read from a uniform buffer
    // object within that set.  This flag results in empty descriptor sets being bound for any
    // unused descriptor set to work around this issue.  http://anglebug.com/2727
    Feature bindEmptyForUnusedDescriptorSets = {
        "bind_empty_for_unused_descriptor_sets", FeatureCategory::VulkanWorkarounds,
        "On Qualcomm, gaps in bound descriptor set indices causes the post-gap sets to misbehave",
        &members, "http://anglebug.com/2727"};
    // When the scissor is (0,0,0,0) on Windows Intel, the driver acts as if the scissor was
    // disabled.  Work-around this by setting the scissor to just outside of the render area
    // (e.g. (renderArea.x, renderArea.y, 1, 1)). http://anglebug.com/3407
    Feature forceNonZeroScissor = {
        "force_non_zero_scissor", FeatureCategory::VulkanWorkarounds,
        "On Windows Intel, when the scissor is (0,0,0,0), the driver acts as if the "
        "scissor was disabled",
        &members, "http://anglebug.com/3407"};
    // OES_depth_texture is a commonly expected feature on Android. However it
    // requires that D16_UNORM support texture filtering
    // (e.g. VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT) and some devices
    // do not. Work-around this by setting saying D16_UNORM supports filtering
    // anyway.
    Feature forceD16TexFilter = {"force_D16_texture_filter", FeatureCategory::VulkanWorkarounds,
                                 "On some Android devices, VK_FORMAT_D16_UNORM does not support "
                                 "VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_LINEAR_BIT, "
                                 "which prevents OES_depth_texture from being supported.",
                                 &members, "http://anglebug.com/3452"};
    // On some android devices, vkCmdBlitImage with flipped coordinates blits incorrectly.  This
    // workaround makes sure this path is avoided.  http://anglebug.com/3498
    Feature disableFlippingBlitWithCommand = {
        "disable_flipping_blit_with_command", FeatureCategory::VulkanWorkarounds,
        "On some android devices, vkCmdBlitImage with flipped coordinates blits incorrectly.",
        &members, "http://anglebug.com/3498"};
    // On platform with Intel or AMD GPU, a window resizing would not trigger the vulkan driver to
    // return VK_ERROR_OUT_OF_DATE on swapchain present.  Work-around by query current window extent
    // every frame to detect a window resizing.
    // http://anglebug.com/3623, http://anglebug.com/3624, http://anglebug.com/3625
    Feature perFrameWindowSizeQuery = {
        "per_frame_window_size_query", FeatureCategory::VulkanWorkarounds,
        "On platform with Intel or AMD gpu, vulkan swapchain is not returning VK_ERROR_OUT_OF_DATE"
        "when window resizing",
        &members, "http://anglebug.com/3623, http://anglebug.com/3624, http://anglebug.com/3625"};
    // On Pixel1XL and Pixel2, reset a vkCommandBuffer seems to have side effects on binding
    // descriptor sets to it afterwards, Work-around by keep using transient vkCommandBuffer on
    // those devices.
    // http://b/135763283
    Feature transientCommandBuffer = {
        "transient_command_buffer", FeatureCategory::VulkanWorkarounds,
        "On Pixel2, keep using transient vkCommandBuffer to work around driver issue in reseting"
        "vkCommandBuffer",
        &members, "http://b/135763283"};
    // Seamful cube map emulation misbehaves on the AMD windows driver, so it's disallowed.
    Feature disallowSeamfulCubeMapEmulation = {
        "disallow_seamful_cube_map_emulation", FeatureCategory::VulkanWorkarounds,
        "Seamful cube map emulation misbehaves on the AMD windows driver, so it's disallowed",
        &members, "http://anglebug.com/3243"};
};
inline FeaturesVk::FeaturesVk()  = default;
inline FeaturesVk::~FeaturesVk() = default;
}  // namespace angle
#endif  // ANGLE_PLATFORM_FEATURESVK_H_