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[Fix] (Blend): decline an unsupported dual-source blend instead of throwing through the GL ABI

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swung0x48
2026-08-27 10:48:21 -04:00
parent 66867a41ba
commit e1d5bdc4a5
5 changed files with 429 additions and 29 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.cpp
+24 -10
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@@ -5533,18 +5533,32 @@ void main() {
}
}
// Dual-source blending (GL_SRC1_* factors from glBlendFunc paired with
// glBindFragDataLocationIndexed) requires the dualSrcBlend device feature. It is detected at
// device creation and surfaced in the POST; if a shader actually issues a draw with a SRC1
// factor on a device that lacks it, there is no fallback, so hard-fail here at use time
// rather than silently mistranslating the blend equation.
if (effectiveBlendEnabled && !m_dualSrcBlendFeatureEnabled &&
// glBindFragDataLocationIndexed) requires the dualSrcBlend device feature. It is detected
// at device creation and surfaced in the POST; there is no fallback that BLENDS correctly,
// so a draw that asks for a SRC1 factor on a device without the feature gets the blend
// DECLINED - this attachment is baked with blending off and neutral One/Zero factors, and
// the loss is logged once. Both the factors AND the enable have to be neutralised:
// VUID-VkPipelineColorBlendAttachmentState-srcColorBlendFactor-00608 and its three
// siblings forbid a VK_BLEND_FACTOR_SRC1_* in the struct without the feature whatever
// blendEnable says, so clearing only the enable would still be invalid pipeline state.
// The previous behaviour, throwing, took the whole process down over one unsupported
// blend factor; this is defined, survivable and visible in the log, and it matches what
// the non-blendable-format arm above already does.
if (!m_dualSrcBlendFeatureEnabled &&
(IsDualSourceBlendFactor(srcRGB) || IsDualSourceBlendFactor(dstRGB) ||
IsDualSourceBlendFactor(srcAlpha) || IsDualSourceBlendFactor(dstAlpha))) {
THROW_EXCEPTION(
"Dual-source blending (GL_SRC1_* blend factor) was used on color attachment " +
std::to_string(i) +
", but the Vulkan device does not support the dualSrcBlend feature (see the "
"dualSrcBlend row in the driver POST). No fallback exists; the draw cannot proceed.");
MGLOG_E_ONCE(
"GetOrCreatePipeline: dual-source blending (GL_SRC1_* blend factor) was requested on "
"color attachment %u, but the Vulkan device does not support the dualSrcBlend feature "
"(see the dualSrcBlend row in the driver POST). Blending is DECLINED on that "
"attachment - the fragment's first output is written unblended and the second source "
"is dropped (program=%u)",
i, program.GetExternalIndex());
effectiveBlendEnabled = false;
srcRGB = BlendFactor::One;
dstRGB = BlendFactor::Zero;
srcAlpha = BlendFactor::One;
dstAlpha = BlendFactor::Zero;
}
payload.colorBlendAttachments[i] = MakeColorBlendAttachmentState(
effectiveBlendEnabled,