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[Fix] (DirectVulkan): shrink the blended depth-write quirk to MIN/MAX extremum blends only - a fixture-wide trace sweep showed the additive ONE+ONE arm never fires on the 26.3 OIT chain (its accumulation passes disable depth writes themselves) and only hit unrelated additive glow content; also fail reflection toward the gl_FragDepth exemption and zero phantom default-FBO blend slots so stale indexed state cannot trigger the strip

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swung0x48
2026-07-20 23:39:28 -04:00
parent bce9c48c8e
commit 202037b5a3
5 changed files with 53 additions and 35 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/PipelineFactory.cpp
+17 -17
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@@ -131,25 +131,25 @@ namespace MobileGL::MG_Backend::DirectVulkan {
}
namespace {
// Order-independent accumulation blending: the write order of overlapping fragments
// does not change the result, which is what lets multi-pass chains re-rasterize the
// same geometry and combine per-pass contributions (MC 26.3 OIT: GL_MAX depth
// bounds, additive ONE+ONE transmittance/accumulate). Sorted-transparency "over"
// compositing (SRC_ALPHA-style factors) is order-dependent, drawn once per surface,
// and relies on its depth writes for occlusion - it must not be treated as hazardous.
// MIN/MAX ignore blend factors entirely per the Vulkan spec.
// MIN/MAX extremum blending: the signature of a depth-bounds accumulation pass
// (MC 26.3 OIT writes vec4(-linD, linD, deviceZ, 0) under GL_MAX while writing
// depth for its equality chain). MIN/MAX ignore blend factors per the Vulkan spec.
//
// Deliberately color-channel only. A separate-alpha accumulation
// (glBlendEquationSeparate(GL_FUNC_ADD, GL_MAX)) whose color channel is an ordinary
// over-blend is not treated as hazardous: no known content pairs that shape with a
// depth-equality chain, and widening the test would re-capture sorted transparency.
// Deliberately the ONLY shape stripped. A quirk should touch as little unrelated
// content as possible, and a trace sweep of every fixture showed the wider
// alternatives all cost more than they fix:
// - additive ONE+ONE with a depth write matched zero draws of the 26.3 chain
// (its transmittance/accumulate passes disable depth writes themselves) - the
// only real content it caught was harmless additive glow effects (Create);
// - sorted-transparency "over" blends (SRC_ALPHA-style) are order-dependent,
// drawn once per surface, and rely on their depth writes for occlusion;
// - separate-alpha accumulation over an over-blending color channel has no
// known pairing with a depth-equality chain (color channel only, see tests).
// If a future workload pairs another blend shape with an equality chain, widen
// this with that evidence in hand rather than pre-emptively.
Bool IsAccumulationBlend(const VkPipelineColorBlendAttachmentState& attachment) {
if (attachment.colorBlendOp == VK_BLEND_OP_MIN || attachment.colorBlendOp == VK_BLEND_OP_MAX) {
return true;
}
return attachment.colorBlendOp == VK_BLEND_OP_ADD &&
attachment.srcColorBlendFactor == VK_BLEND_FACTOR_ONE &&
attachment.dstColorBlendFactor == VK_BLEND_FACTOR_ONE;
return attachment.colorBlendOp == VK_BLEND_OP_MIN ||
attachment.colorBlendOp == VK_BLEND_OP_MAX;
}
} // namespace