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KhronosGroup / MoltenVK

MoltenVK is a Vulkan Portability implementation. It layers a subset of the high-performance, industry-standard Vulkan graphics and compute API over Apple's Metal graphics framework, enabling Vulkan applications to run on macOS, iOS and tvOS.
Apache License 2.0
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Emulate sampler lod bias #2163

Open aitor-lunarg opened 9 months ago

aitor-lunarg commented 9 months ago

2142 tries to tackle this issue exposing internal Metal SPIs. Unfortunately, even with MVK_USE_METAL_PRIVATE_API enabled, there are still CTS tests failing in the M3 chip family. Proposed solution is to emulate as pointed out in https://github.com/KhronosGroup/MoltenVK/pull/2142#issuecomment-1913173117

Failing CTS tests:

dEQP-VK.pipeline.monolithic.sampler.max_sampler_lod_bias.sampler_bias
aitor-lunarg commented 5 months ago

I think it would be beneficial to rework how samplers are passed to Metal so that we pass the following data per sampler:

Then modify the shader to add bias (since bias is implemented in shader for Metal) and handle opaque black and as a nice side effect support custom border color (unsure if MoltenVK has support for this, I think not).

Refer to https://github.com/KhronosGroup/Vulkan-Portability/issues/37#issuecomment-2154637160 for the custom border color.

Mentioning this because it could be a unified effort to support bias and border color since both require similar changes.