[Impeller] MoltenVK and triangle fans usage in Vulkan needs workarounds. #158024
Description
Super low priority. On the Mac, there must be a cap check for the triangle primitive topology when the portability subset extension is enabled (which SwiftShader wont enable by Molten will). Otherwise, there will be rendering errors.
--- Vulkan Debug Report ----------------------------------------
| Severity: Error
| Type: { Validation }
| ID Name: VUID-VkPipelineInputAssemblyStateCreateInfo-triangleFans-04452
| ID Number: 1316858618
| Queue Breadcrumbs: [NONE]
| CMD Buffer Breadcrumbs: [NONE]
| Trigger: Validation Error: [ VUID-VkPipelineInputAssemblyStateCreateInfo-triangleFans-04452 ] | MessageID = 0x4e7daafa | vkCreateGraphicsPipelines(): pCreateInfos[0] (portability error): VK_PRIMITIVE_TOPOLOGY_TRIANGLE_FAN is not supported. The Vulkan spec states: If the VK_KHR_portability_subset extension is enabled, and VkPhysicalDevicePortabilitySubsetFeaturesKHR::triangleFans is VK_FALSE, topology must not be VK_PRIMITIVE_TOPOLOGY_TRIANGLE_FAN (https://vulkan.lunarg.com/doc/view/1.3.280.0/mac/1.3-extensions/vkspec.html#VUID-VkPipelineInputAssemblyStateCreateInfo-triangleFans-04452)
-----------------------------------------------------------------