Default line width causes drawState error

[ioquatix]

Vulkan-Hpp/vulkan/vulkan.hpp

Line 7079 in 43ec5d8

PipelineRasterizationStateCreateInfo( PipelineRasterizationStateCreateFlags flags_ = PipelineRasterizationStateCreateFlags(), Bool32 depthClampEnable_ = 0, Bool32 rasterizerDiscardEnable_ = 0, PolygonMode polygonMode_ = PolygonMode::eFill, CullModeFlags cullMode_ = CullModeFlags(), FrontFace frontFace_ = FrontFace::eCounterClockwise, Bool32 depthBiasEnable_ = 0, float depthBiasConstantFactor_ = 0, float depthBiasClamp_ = 0, float depthBiasSlopeFactor_ = 0, float lineWidth_ = 0 )

causes

[T+0.098 main ERROR] DS Attempt to set lineWidth to 0.000000 but physical device limits line width to between [0.500000, 10.000000]!

Is there a reasonable default (e.g. 1?)

[asuessenbach]

Unfortunately, vk.xml does not specify any defaults.
And I don't see, how one could derive some default that's more meaningful than just zero. I would have expected that value to be supported on every platform, at least as a value with some special meaning.

[ioquatix]

Yeah, that makes sense. Unfortunately, as a default, it's not valid at least on this hardware.

[mtavenrath]

During the last Khronos Vulkan DevU event the idea came up to something like a 'vk_defaults.xml' file where one could define multiple useful default parameters for CreateInfo structs. This file could be used to create a factory library which would allow you to write something like:

foo::createComponentMapping(foo::ComponentMapping::RGBA)
or
foo::createComponentMapping(foo::ComponentMapping::BGRA

The idea is to have reasonable defaults for all objects where applicable with the option for developers to define their own default values.

One question which comes up if Vulkan-Hpp should use this file too for the default values. Since this will affect source code compatibility unfortunately I'd have to say no.

[ioquatix]

@mtavenrath That's an awesome idea.

If you are worried about source code compatibility, I guess I could relate. But:

1/ Bump major version?
2/ It hasn't been a problem in the past? (major changes to header breaking existing code)
3/ Make it optional?

[mtavenrath]

Default values should be implemented outside of Vulkan-Hpp in a factory-like utility library. Closing.