VK_FORMAT_R8G8B8A8_SRGB is not a supported vertex buffer format

[lain-dono]

When I try to use wgpu::VertexAttributeDescriptor with format wgpu::VertexFormat::Ushort2Norm, I get the error:

ERROR 2019-03-11T01:06:21Z: gfx_backend_vulkan: [Validation] [ VUID-VkVertexInputAttributeDescription-format-00623 ] Object: VK_NULL_HANDLE (Type = 0) | vkCreateGraphicsPipelines: pCreateInfo[0].pVertexInputState->vertexAttributeDescriptions[2].format (VK_FORMAT_R8G8B8A8_SRGB) is not a supported vertex buffer format. The Vulkan spec states: format must be allowed as a vertex buffer format, as specified by the VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT flag in VkFormatProperties::bufferFeatures returned by vkGetPhysicalDeviceFormatProperties (https://www.khronos.org/registry/vulkan/specs/1.1-extensions/html/vkspec.html#VUID-VkVertexInputAttributeDescription-format-00623)

I think that it is:

wgpu/wgpu-native/src/conv.rs

Lines 376 to 380 in 004b43c

	UcharNorm => H::R8Srgb,
	Uchar2Norm => H::Rg8Srgb,
	Uchar3Norm => H::Rgb8Srgb,
	Uchar4Norm => H::Rgba8Srgb,
	Uchar4NormBgra => H::Bgra8Srgb,

Should be like this:

        UcharNorm => H::R8Unorm, 
        Uchar2Norm => H::Rg8Unorm, 
        Uchar3Norm => H::Rgb8Unorm, 
        Uchar4Norm => H::Rgb8Unorm, 
        Uchar4NormBgra => H::Bgra8Unorm, 

[kvark]

Thanks for filing the issue and fixing it!
btw, it's a convention to say "fixes #xxxx" in your PR description, which tells Github to automatically close the associated issue upon merging

[kvark]

Fixed by #100