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[Feat] (DirectVulkan, MG_Util): honour a glVertexAttribDivisor other than 1

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Vulkan's VK_VERTEX_INPUT_RATE_INSTANCE advances an attribute once per instance and has
no way to say anything else, so every non-zero divisor collapsed to 1: an attribute the
application asked to change every three instances changed every one, and
KHR-GL40.draw_indirect.basic-drawArrays-instancing and its elements sibling drew the
wrong colours from instance one onward.

VK_EXT_vertex_attribute_divisor is exactly this state, so it is enabled when the device
has it and the per-binding divisors ride into the pipeline through
VkPipelineVertexInputDivisorStateCreateInfoEXT. Only divisors other than 1 are listed -
1 is what the plain input rate already means - and they join the layout hash, so two
layouts that differ only in a divisor no longer share a pipeline.

POST reports the feature either way, because without it the failure is silent and looks
like a shader bug: the attribute is fetched, just from the wrong instance. The GLES side
gains the two checks this session's other work made load-bearing for the same reason -
glPatchParameteri (without it GL_PATCH_VERTICES stays at the driver's 3 and a patch draw
of any other size renders nothing) and the transform feedback object entry points
(without them a second object cannot open a capture while the first is paused).

KHR-GL40.draw_indirect on Magma: 70/70 but for the arbitrary primitive-restart index,
which Vulkan cannot express at all.
This commit is contained in:
BZLZHH
2026-08-04 19:25:32 -04:00
parent a50b2c422b
commit cff959b2e8
5 changed files with 99 additions and 0 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/VertexInputStateFactory.cpp
+18
View File
@@ -87,6 +87,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
Vector<Uint32> bindingAttributeLocations;
Vector<Bool> bindingUsesClientMemory;
Vector<VertexStreamConversion> bindingConversions;
Vector<VkVertexInputBindingDivisorDescriptionEXT> bindingDivisors;
Uint32 unsupportedAttribMask = 0;
for (Uint32 location = 0; location < MG_State::GLState::VertexArrayObject::MAX_VERTEX_ATTRIBS; ++location) {
@@ -180,6 +181,11 @@ namespace MobileGL::MG_Backend::DirectVulkan {
bindingConversions.push_back(conversion);
builder.AddBinding(binding, stride, inputRate);
builder.AddAttribute(location, binding, vkFormat, 0);
// Divisor 1 is what VK_VERTEX_INPUT_RATE_INSTANCE already means; only anything
// else needs the extension to say it.
if (inputRate == VK_VERTEX_INPUT_RATE_INSTANCE && attr.Divisor != 1) {
bindingDivisors.push_back({binding, static_cast<Uint32>(attr.Divisor)});
}
}
const auto& state = builder.Build();
@@ -191,6 +197,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
BackendVertexInputState& entry = *slot;
entry.hash = hash;
entry.lastUsedFrameBoundary = m_frameBoundaryCounter;
entry.bindingDivisors = Move(bindingDivisors);
entry.bindings = builder.GetBindings();
entry.attributes = builder.GetAttributes();
// See the layoutHash declaration: hash only the resolved layout, never
@@ -207,6 +214,10 @@ namespace MobileGL::MG_Backend::DirectVulkan {
XXHASH_VERIFY(XXH64_update(m_hashState, &attribute.format, sizeof(attribute.format)));
XXHASH_VERIFY(XXH64_update(m_hashState, &attribute.offset, sizeof(attribute.offset)));
}
for (const auto& divisor : entry.bindingDivisors) {
XXHASH_VERIFY(XXH64_update(m_hashState, &divisor.binding, sizeof(divisor.binding)));
XXHASH_VERIFY(XXH64_update(m_hashState, &divisor.divisor, sizeof(divisor.divisor)));
}
XXHASH_VERIFY(XXH64_update(m_hashState, &unsupportedAttribMask, sizeof(unsupportedAttribMask)));
entry.layoutHash = XXH64_digest(m_hashState);
entry.attributeLocationMask = 0;
@@ -224,6 +235,13 @@ namespace MobileGL::MG_Backend::DirectVulkan {
entry.state = state;
entry.state.pVertexBindingDescriptions = entry.bindings.empty() ? nullptr : entry.bindings.data();
entry.state.pVertexAttributeDescriptions = entry.attributes.empty() ? nullptr : entry.attributes.data();
if (!entry.bindingDivisors.empty()) {
entry.divisorState.vertexBindingDivisorCount = static_cast<Uint32>(entry.bindingDivisors.size());
entry.divisorState.pVertexBindingDivisors = entry.bindingDivisors.data();
entry.state.pNext = &entry.divisorState;
} else {
entry.state.pNext = nullptr;
}
return entry;
}
MobileGL/MG_Backend/DirectVulkan/Renderer/VertexInputStateFactory.h
+8
View File
@@ -53,6 +53,14 @@ namespace MobileGL::MG_Backend::DirectVulkan {
// Bitmask of `attributes[i].location` - the draw path needs it up to
// three times per draw, so it is baked once at build time.
Uint32 attributeLocationMask = 0;
// Per-binding glVertexAttribDivisor values other than 1. Vulkan's instance input
// rate advances once per instance and nothing else, so anything else has to be
// stated through VK_EXT_vertex_attribute_divisor. Empty when every instanced
// binding uses divisor 1, which is what the plain input rate already means.
Vector<VkVertexInputBindingDivisorDescriptionEXT> bindingDivisors;
VkPipelineVertexInputDivisorStateCreateInfoEXT divisorState{
VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_DIVISOR_STATE_CREATE_INFO_EXT
};
VkPipelineVertexInputStateCreateInfo state{
VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO
};
MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.cpp
+30
View File
@@ -9894,6 +9894,36 @@ void main() {
MGLOG_W("VK_EXT_transform_feedback is unavailable; transform feedback capture will not work");
}
// VK_EXT_vertex_attribute_divisor. Vulkan's instance input rate advances an attribute
// once per instance and nothing else, so without this every glVertexAttribDivisor value
// collapses to 1 and an attribute meant to change every N instances changes every one.
m_vertexAttributeDivisorEnabled = false;
VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT vertexAttributeDivisorFeatures{};
vertexAttributeDivisorFeatures.sType =
VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VERTEX_ATTRIBUTE_DIVISOR_FEATURES_EXT;
if (IsExtensionSupported(availableExtensions, VK_EXT_VERTEX_ATTRIBUTE_DIVISOR_EXTENSION_NAME) &&
getPhysicalDeviceFeatures2 != nullptr) {
VkPhysicalDeviceFeatures2 featureQuery{};
featureQuery.sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_FEATURES_2;
featureQuery.pNext = &vertexAttributeDivisorFeatures;
getPhysicalDeviceFeatures2(m_physicalDevice.handle, &featureQuery);
if (vertexAttributeDivisorFeatures.vertexAttributeInstanceRateDivisor == VK_TRUE) {
if (!IsExtensionAlreadyEnabled(enabledDeviceExtensions,
VK_EXT_VERTEX_ATTRIBUTE_DIVISOR_EXTENSION_NAME)) {
enabledDeviceExtensions.push_back(VK_EXT_VERTEX_ATTRIBUTE_DIVISOR_EXTENSION_NAME);
}
vertexAttributeDivisorFeatures.vertexAttributeInstanceRateZeroDivisor = VK_FALSE;
vertexAttributeDivisorFeatures.pNext = const_cast<void*>(deviceCreateInfo.pNext);
deviceCreateInfo.pNext = &vertexAttributeDivisorFeatures;
m_vertexAttributeDivisorEnabled = true;
MGLOG_I("Enabled optional device extension: %s", VK_EXT_VERTEX_ATTRIBUTE_DIVISOR_EXTENSION_NAME);
}
}
if (!m_vertexAttributeDivisorEnabled) {
MGLOG_W("VK_EXT_vertex_attribute_divisor is unavailable; a glVertexAttribDivisor other "
"than 1 will advance its attribute once per instance");
}
// Host query reset lets the occlusion-query ring recycle slots without a
// command-buffer round trip.
m_hostQueryResetEnabled = false;
MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.h
+3
View File
@@ -494,6 +494,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
// VK_EXT_transform_feedback (GL transform feedback capture)
Bool m_transformFeedbackFeatureEnabled = false;
// VK_EXT_vertex_attribute_divisor: without it every non-zero glVertexAttribDivisor
// behaves as 1, because that is all Vulkan's instance input rate can express.
Bool m_vertexAttributeDivisorEnabled = false;
static inline PFN_vkCmdBindTransformFeedbackBuffersEXT s_vkCmdBindTransformFeedbackBuffersEXT = nullptr;
static inline PFN_vkCmdBeginTransformFeedbackEXT s_vkCmdBeginTransformFeedbackEXT = nullptr;
static inline PFN_vkCmdEndTransformFeedbackEXT s_vkCmdEndTransformFeedbackEXT = nullptr;
MobileGL/MG_Util/SelfTest/DriverPost.cpp
+40
View File
@@ -298,6 +298,25 @@ namespace MobileGL::MG_Util::SelfTest {
"not supported; no impact: the native indirect path deliberately does not "
"rely on it (shader-side emulation handles baseInstance semantics)");
}
if (glesFuncs.glPatchParameteri != nullptr) {
builder.Pass("Tessellation patch parameters",
"glPatchParameteri present (GL_PATCH_VERTICES reaches the driver)");
} else {
builder.Warn("Tessellation patch parameters",
"glPatchParameteri missing (pre-ES 3.2 without GL_EXT_tessellation_shader); "
"GL_PATCH_VERTICES stays at the driver default of 3 and a patch draw of any "
"other size renders nothing");
}
if (glesFuncs.glGenTransformFeedbacks != nullptr && glesFuncs.glBindTransformFeedback != nullptr &&
glesFuncs.glPauseTransformFeedback != nullptr && glesFuncs.glResumeTransformFeedback != nullptr) {
builder.Pass("Transform feedback objects",
"supported (each GL transform feedback object gets one of the driver's, so "
"several can hold a paused capture at once)");
} else {
builder.Warn("Transform feedback objects",
"entry points missing; every GL transform feedback object shares the driver's "
"default one, so a second object cannot open a capture while the first is paused");
}
if (caps.SupportsNorm16Texture) {
builder.Pass("GL_EXT_texture_norm16", "supported");
} else {
@@ -1412,6 +1431,27 @@ namespace MobileGL::MG_Util::SelfTest {
"hard-fails at draw");
}
Bool vertexAttributeInstanceRateDivisor = false;
if (vkGetPhysicalDeviceFeatures2Fn != nullptr &&
HasVkExtension(deviceExtensions, VK_EXT_VERTEX_ATTRIBUTE_DIVISOR_EXTENSION_NAME)) {
VkPhysicalDeviceVertexAttributeDivisorFeaturesEXT divisorFeatures{};
divisorFeatures.sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_VERTEX_ATTRIBUTE_DIVISOR_FEATURES_EXT;
VkPhysicalDeviceFeatures2 features2{};
features2.sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_FEATURES_2;
features2.pNext = &divisorFeatures;
vkGetPhysicalDeviceFeatures2Fn(physicalDevice, &features2);
vertexAttributeInstanceRateDivisor = divisorFeatures.vertexAttributeInstanceRateDivisor == VK_TRUE;
}
if (vertexAttributeInstanceRateDivisor) {
builder.Pass("vertexAttributeInstanceRateDivisor",
"supported (glVertexAttribDivisor advances an attribute every N instances)");
} else {
builder.Warn("vertexAttributeInstanceRateDivisor",
"unsupported; Vulkan's instance input rate can only advance once per instance, so "
"every non-zero glVertexAttribDivisor behaves as 1 and instanced attributes meant to "
"change every N instances change every one");
}
if (vkGetPhysicalDeviceProperties2Fn != nullptr && properties.apiVersion >= VK_API_VERSION_1_1) {
VkPhysicalDeviceSubgroupProperties subgroupProperties{};
subgroupProperties.sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_SUBGROUP_PROPERTIES;