[dani10gl]

Summary

This PR addresses several issues in the Vulkan temporal upscaler pipeline (vk_temporal.cpp, vk_dlss.cpp, vk_menu.cpp, dlss_checks.h) where NVIDIA DLSS would either fail to instantiate during dynamic resolution scaling (DRS) or permanently latch into a disabled state (engine.failed = true), silently falling back to bilinear upscaling without any user-facing recovery path.

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Problem Description & Root Causes

1. Permanent Failure Latching in vk_temporal.cpp:

   • When a transient evaluation error occurs (e.g. during screen transition, window resize, or dynamic resolution shift), vk_temporal.cpp unconditionally sets engine.failed = true.
   • Once latched, temporal_upscale() perpetually rejects all future frames with "it failed earlier".
   • Changing options in the Insert menu (switching between presets, render resolutions, or upscaler modes) never cleared this state, leaving DLSS dead for the remainder of the application lifecycle.

2. Off-by-One Rejection in dlss_checks.h:

   • In scene_size_fits(), (uint64_t)w * 3 >= ow fails for fractional roundings at 33% Ultra Performance scaling (e.g., $853 \times 3 = 2559 < 2560$).
   • A tolerance margin of 2 pixels prevents false rejections of valid render targets.

3. retry flag left false for DLSS in vk_dlss.cpp:

   • TemporalEngine contains a retry boolean intended for transient evaluation drops. Setting this to true allows DLSS to retry on subsequent frames if a single frame evaluation fails, rather than permanently falling back.

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Changes

• gpu/vk/dlss_checks.h:

  • Adjusted scene_size_fits() to (uint64_t)(w + 2) * 3 >= ow && (uint64_t)(h + 2) * 3 >= oh to safely handle rounding in fractional 3x downscaling.

• gpu/vk/vk_dlss.cpp:

  • Set retry = true in TemporalEngine kEngine for DLSS to ensure transient evaluation failures reset history on the next frame instead of shutting down the engine permanently.

• gpu/vk/vk_temporal.h & gpu/vk/vk_temporal.cpp:

  • Implemented void temporal_reset_failure() to clear engine.failed across active engines, reset s.reason, and allow clean reinitialization.

• gpu/vk/vk_menu.cpp:

  • Hooked temporal_reset_failure() into set_row() when modifying opts.dlss, opts.resolution, or opts.dlss_model. Modifying scaling settings in the Insert menu now cleanly clears previous errors and hot-reloads the upscaler.

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Verification

• Tested with Hookshot v2.1.0 on Vulkan with an NVIDIA RTX GPU using DLSS runtime nvngx_dlss.dll (v310.9.16).
• Verified seamless switching between:
  • Dynamic Resolution ("Auto") and fixed targets (33%, 50%, 58%, 67%, 75%, 83%, 100%).
  • DLSS models (Presets K, M, L, Default).
  • Switching between FSR 3.1 and DLSS without image degradation or permanent fallback to bilinear scaling.
• Compiled clean on LLVM-MinGW x86_64 with zero warnings or errors.