Gauntlet Legends: Fixing Flickering Textures In Flycast D3D11

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Are you experiencing annoying flickering dots on textures in Gauntlet Legends when using the Direct3D 11 renderer in Flycast? You're not alone! This article dives into the issue, exploring potential causes, debugging steps, and possible solutions to get your game looking as good as new.

The Flickering Dots Issue in Gauntlet Legends

So, you fired up Gauntlet Legends on Flycast, selected the Direct3D 11 renderer, and bam!—flickering dots all over certain textures. It's distracting, makes the game look glitchy, and generally ruins the experience. The main keyword here is the flickering dots effect that appears on some textures within Gauntlet Legends specifically when using the Direct3D 11 renderer in the Flycast emulator. This issue seems to be isolated to D3D11, as other renderers like OpenGL, Vulkan, and Direct3D 9 don't exhibit the same problem. It's crucial to understand that this isn't a universal problem affecting all games or all systems, but rather a specific interaction between this particular game, the emulator, and the D3D11 rendering pipeline. This means the solution might involve tweaking settings specific to this combination, rather than a broad fix for the entire emulator. The impact of this issue is significant, detracting from the visual experience and potentially affecting gameplay by making it harder to discern details. Furthermore, its presence only in D3D11 suggests a potential bug or optimization issue within the emulator's implementation of this renderer. This needs to be addressed to ensure consistent and accurate rendering across all supported graphics APIs.

Why Direct3D 11?

You might be wondering, "Why is this happening in Direct3D 11 and not the other renderers?" Good question! Direct3D 11, while a mature and widely supported API, has its own quirks and implementation details. It's possible that Flycast's D3D11 renderer is interacting with the game's textures in a way that triggers this flickering effect. This could be due to a variety of factors, such as differences in how transparency is handled, how textures are filtered, or how shaders are compiled. Direct3D 11 is a graphics API developed by Microsoft, used by Flycast to render graphics. The Direct3D 11 rendering errors are not present in OpenGL, Vulkan, or Direct3D 9. The flickering dots are likely due to how Direct3D 11 handles certain texture properties or shader operations specific to Gauntlet Legends. The underlying issue could stem from precision differences, uninitialized variables, or incorrect assumptions made during the rendering process. Debugging this requires a deep understanding of both the game's rendering techniques and the Flycast emulator's D3D11 implementation. Furthermore, driver-specific issues on different GPUs might exacerbate the problem, making it harder to pinpoint the exact cause. Addressing this flickering issue will likely involve profiling the D3D11 rendering pipeline, inspecting shader code, and potentially adjusting texture filtering parameters to ensure accurate and stable rendering. The goal is to identify and rectify any discrepancies between the intended visual output and the actual rendered result, thereby eliminating the distracting flickering effect and enhancing the overall gaming experience.

Debugging Steps and Findings

Let's break down the debugging steps taken to diagnose this issue. One user reported trying various troubleshooting methods, including:

  • Testing older versions of Flycast: This helps determine if the issue is a recent regression.
  • Enabling full framebuffer emulation: While this sometimes fixes rendering issues, it actually made the flickering worse in this case. Enabling full framebuffer emulation can sometimes exacerbate rendering issues due to increased memory usage and processing overhead. This suggests that the root cause of the flickering is not related to framebuffer precision or accuracy, but rather to some other aspect of the rendering pipeline. The observed increase in flickering with full framebuffer emulation enabled might indicate that the underlying issue is amplified by increased memory bandwidth demands or by changes in the order in which rendering operations are performed. It is also possible that enabling full framebuffer emulation introduces additional synchronization points, which could inadvertently expose race conditions or other timing-related issues within the rendering code. Therefore, while disabling full framebuffer emulation might not directly resolve the flickering, it could help to reduce its severity or to simplify the debugging process by eliminating one potential source of interference. The user also attempted to force Flycast to use the integrated Intel GPU, without success. This is relevant because it indicates that the issue is likely not specific to the discrete Nvidia GPU, but rather to the way Flycast interacts with D3D11 in general. This is consistent with the observation that the flickering does not occur on a different computer with only an integrated Intel GPU. Therefore, the root cause of the flickering is likely to be found in the interaction between Flycast, D3D11, and the specific rendering techniques used by Gauntlet Legends.

Hardware and Software Configuration

The user's hardware and software setup includes:

  • Operating System: Windows 10
  • CPU: Intel i5-8300H @ 2.30 GHz
  • Integrated GPU: Intel UHD 630
  • Discrete GPU: NVIDIA GTX 1050 (Mobile)
  • RAM: 8GB

It's interesting to note that the issue doesn't occur on a separate computer with only an Intel HD 620 integrated GPU. This suggests that the combination of the discrete NVIDIA GPU and the specific way Flycast uses Direct3D 11 might be the key to triggering the problem. The Flycast emulator D3D11 texture problem seems related to a combination of factors, including the specific GPU architecture, driver version, and the way Flycast's D3D11 renderer interacts with the game's textures. It's possible that the discrete GPU is exposing a bug or incompatibility that is not present on the integrated GPU. The drivers for the discrete GPU might also be playing a role, as different driver versions can sometimes introduce or resolve rendering issues. Another possibility is that the discrete GPU is running the game at a higher resolution or with different settings than the integrated GPU, which could be exacerbating the flickering issue. Further investigation might involve experimenting with different driver versions, adjusting graphics settings within Flycast, and profiling the D3D11 rendering pipeline to identify any performance bottlenecks or incorrect rendering operations. Ultimately, the goal is to determine whether the flickering is caused by a bug in Flycast, a driver issue, or some other underlying problem, and then to develop a fix or workaround that eliminates the issue.

Analyzing the Logs

The provided logs offer some clues. Let's break them down:

  • DX11 Context Initialization: The logs confirm that Flycast is initializing the Direct3D 11 context.
  • Shader Loading: Flycast is loading shaders from the dx11_shader_cache.bin and dx11oit_shader_cache.bin files. Corrupted or outdated shaders could potentially cause rendering issues. Loaded shaders from the cache might be incompatible with the specific GPU or driver version being used. It is possible that the shader compilation process is generating incorrect or suboptimal code, which could lead to the flickering issue. Therefore, clearing the shader cache and forcing Flycast to recompile the shaders might help to resolve the problem. Another possibility is that the shaders are not being properly optimized for the specific hardware configuration, which could be causing performance bottlenecks and rendering artifacts. Further investigation might involve analyzing the shader code to identify any potential issues, experimenting with different shader optimization settings, and profiling the rendering pipeline to determine whether the shaders are contributing to the flickering. Ultimately, the goal is to ensure that the shaders are being compiled and executed correctly, and that they are not causing any rendering errors.
  • Format B4G4R4A4 Warning: The warning about "Format B4G4R4A4 doesn't support mipmap autogen" might be relevant. Mipmaps are pre-calculated, lower-resolution versions of textures used to improve rendering performance and reduce aliasing. If mipmap generation is not working correctly for this texture format, it could lead to visual artifacts. The format B4G4R4A4 might be causing issues because it is not being handled correctly by the D3D11 renderer, or because it is incompatible with certain texture filtering operations. It is possible that the texture format is not being properly converted or resampled, which could lead to visual artifacts such as the flickering dots. Another possibility is that the texture format is not being properly mipmapped, which could cause aliasing and other rendering issues. Further investigation might involve experimenting with different texture formats, adjusting texture filtering settings, and profiling the rendering pipeline to determine whether the texture format is contributing to the flickering. Ultimately, the goal is to ensure that the textures are being handled correctly by the D3D11 renderer, and that they are not causing any rendering errors.

Potential Solutions and Workarounds

Based on the debugging steps and log analysis, here are some potential solutions and workarounds to try:

  1. Clear the Shader Cache: Delete the dx11_shader_cache.bin and dx11oit_shader_cache.bin files in Flycast's data directory. This will force Flycast to recompile the shaders, which might fix any corruption issues.
  2. Experiment with Texture Filtering Settings: Try changing the texture filtering settings in Flycast's graphics options. Anisotropic filtering or different filtering modes might help to reduce or eliminate the flickering.
  3. Update Graphics Drivers: Ensure you have the latest graphics drivers installed for your NVIDIA GTX 1050. Newer drivers often include bug fixes and performance improvements that could resolve the issue. You can update graphics drivers by visiting the NVIDIA website or using the NVIDIA GeForce Experience application. Updated drivers might include bug fixes or performance improvements that specifically address rendering issues with D3D11. It is also possible that the existing drivers are corrupted or outdated, which could be causing the flickering. Therefore, updating the drivers is a good first step in troubleshooting the issue. Another possibility is that the drivers are not properly configured for the specific hardware configuration, which could be causing performance bottlenecks and rendering artifacts. Further investigation might involve experimenting with different driver versions, adjusting graphics settings within the NVIDIA control panel, and profiling the rendering pipeline to determine whether the drivers are contributing to the flickering. Ultimately, the goal is to ensure that the drivers are functioning correctly and that they are not causing any rendering errors.
  4. Try Different Transparency Sorting Modes: Although the user mentioned that transparency sorting didn't seem to affect the issue, it's still worth experimenting with different modes to see if any of them make a difference.
  5. Force Use of Integrated Graphics (if possible): While the user had trouble forcing Flycast to use the integrated GPU, if you can manage to do so, it would be a valuable test to see if the issue is specific to the discrete GPU.
  6. Report the Bug to Flycast Developers: If none of the above solutions work, report the bug to the Flycast developers on their GitHub page. Provide detailed information about your hardware and software configuration, the debugging steps you've taken, and the logs you've gathered. The flickering dots issue is a rendering problem that requires specific debugging and potential code-level fixes. Reporting the bug allows the developers to investigate the issue and potentially implement a solution in a future version of Flycast.

Conclusion

The flickering dots issue in Gauntlet Legends with Flycast's Direct3D 11 renderer is a peculiar problem, but hopefully, with these debugging steps and potential solutions, you can get your game running smoothly. Remember to experiment with different settings and report your findings to the Flycast developers to help them improve the emulator for everyone. Happy gaming, guys!