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Fix Vulkan FXAA/SMAA handling and ensure proper Scene_ldr transitions #7639

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Merged
BMagnu merged 1 commit into from
Jul 22, 2026
+29 −5
Merged

Fix Vulkan FXAA/SMAA handling and ensure proper Scene_ldr transitions #7639

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28 changes: 26 additions & 2 deletions code/graphics/vulkan/VulkanPostProcessingLDR.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -362,14 +362,38 @@ void VulkanLDR::executeFXAA(vk::CommandBuffer cmd)
nullptr, 0);
}

// FXAA main pass: Scene_luminance → Scene_ldr
// The FXAA main pass discards non-edge fragments (FXAA_DISCARD), so those
// pixels must keep the tonemapped image already sitting in Scene_ldr. That
// requires a load-preserving render pass (loadOp=eLoad) — with the default
// eDontCare/eUndefined pass the discarded pixels are left undefined, which
// on IMR GPUs (NVIDIA) happens to preserve the old contents but on tiled /
// AMD Vega / MoltenVK gets scrambled, leaving only the FXAA-written edge
// pixels visible. Transition Scene_ldr to a color attachment first (mirrors
// executeLightshafts). This also orders the main pass's color writes after
// the prepass's sampled read of Scene_ldr (WAR hazard).
{
ImageBarrier2 barrier;
barrier.image = m_sceneLdr.image;
barrier.levelCount = 1;
barrier.layerCount = 1;
barrier.oldLayout = vk::ImageLayout::eShaderReadOnlyOptimal;
barrier.newLayout = vk::ImageLayout::eColorAttachmentOptimal;
barrier.srcStage = vk::PipelineStageFlagBits2::eFragmentShader;
barrier.srcAccess = vk::AccessFlagBits2::eShaderSampledRead;
barrier.dstStage = vk::PipelineStageFlagBits2::eColorAttachmentOutput;
barrier.dstAccess = vk::AccessFlagBits2::eColorAttachmentRead | vk::AccessFlagBits2::eColorAttachmentWrite;

cmdImageBarrier(cmd, barrier);
}

// FXAA main pass: Scene_luminance → Scene_ldr (loadOp=eLoad preserves non-edge pixels)
graphics::generic_data::fxaa_data fxaaData;
fxaaData.rt_w = static_cast<float>(m_ctx->sceneExtent.width);
fxaaData.rt_h = static_cast<float>(m_ctx->sceneExtent.height);
fxaaData.pad[0] = 0.0f;
fxaaData.pad[1] = 0.0f;

m_ctx->drawFullscreenTriangle(cmd, m_ldrRenderPass,
m_ctx->drawFullscreenTriangle(cmd, m_ldrLoadRenderPass,
m_sceneLdrFB, m_ctx->sceneExtent,
SDR_TYPE_POST_PROCESS_FXAA,
m_sceneLuminance.view, m_ctx->linearSampler,
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6 changes: 3 additions & 3 deletions code/graphics/vulkan/VulkanShaderCompiler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -181,11 +181,11 @@ SCP_string VulkanShaderCompiler::buildHeader(vk::ShaderStageFlagBits /*stage*/,
header += temp;
}
}
} else if (sdrType == SDR_TYPE_POST_PROCESS_FXAA) {
} else if (gr_is_fxaa_mode(Gr_aa_mode) && sdrType == SDR_TYPE_POST_PROCESS_FXAA) {
// GLSL 450 always has textureGather
header += shader_get_fxaa_defines(Gr_aa_mode, true);
} else if (sdrType == SDR_TYPE_POST_PROCESS_SMAA_EDGE || sdrType == SDR_TYPE_POST_PROCESS_SMAA_BLENDING_WEIGHT ||
sdrType == SDR_TYPE_POST_PROCESS_SMAA_NEIGHBORHOOD_BLENDING) {
} else if (gr_is_smaa_mode(Gr_aa_mode) && (sdrType == SDR_TYPE_POST_PROCESS_SMAA_EDGE || sdrType == SDR_TYPE_POST_PROCESS_SMAA_BLENDING_WEIGHT ||
sdrType == SDR_TYPE_POST_PROCESS_SMAA_NEIGHBORHOOD_BLENDING)) {
// GLSL 450 always has textureGather
header += shader_get_smaa_defines(Gr_aa_mode, true);
} else {
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