Added Uniform descriptor type

[tomhog]

Pull Request Template

Description

The Uniform implements a DescriptorBuffer using a DataList of values and the bindingIndex etc. I've also added a UniformValue for convince. This is basically the same as Value only it allows structs as it doesn't implement the serialization of the value it stores. I've also added BasicUniformValue which does implement serialization and macroed all the basic types.

• [x ] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• osg2vsg has been updated to use a Uniform to represent material data. The material struct is usable in the shader.

[vsg-dev]

@tomhog could you regenerate this PR related to the InterfaceImplementation branch as currently this PR is pulling in all my changes in the InterfaceImplementation branch,

[vsg-dev]

I have manually merged this PR into my local InterfaceImplementation branch and get just the changes made. I can potentially check in from there. I am getting compile errors though:
[ 33%] Building CXX object src/vsg/CMakeFiles/vsg.dir/platform/unix/Xcb_Window.cpp.o
In file included from /home/robert/Vulkan/VulkanSceneGraphPrototype/src/vsg/vk/Uniform.cpp:14:0:
/home/robert/Vulkan/VulkanSceneGraphPrototype/include/vsg/vk/Uniform.h: In member function ‘void vsg::BasicUniformValue::read(vsg::Input&)’:
/home/robert/Vulkan/VulkanSceneGraphPrototype/include/vsg/vk/Uniform.h:98:33: error: there are no arguments to ‘value’ that depend on a template parameter, so a declaration of ‘value’ must be available [-fpermissive]
input.read("Value", value());
^~~~~
/home/robert/Vulkan/VulkanSceneGraphPrototype/include/vsg/vk/Uniform.h:98:33: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)
/home/robert/Vulkan/VulkanSceneGraphPrototype/include/vsg/vk/Uniform.h: In member function ‘void vsg::BasicUniformValue::write(vsg::Output&) const’:
/home/robert/Vulkan/VulkanSceneGraphPrototype/include/vsg/vk/Uniform.h:104:35: error: there are no arguments to ‘value’ that depend on a template parameter, so a declaration of ‘value’ must be available [-fpermissive]
output.write("Value", value());
^~~~~
src/vsg/CMakeFiles/vsg.dir/build.make:1622: recipe for target 'src/vsg/CMakeFiles/vsg.dir/vk/Uniform.cpp.o' failed
make[2]: *** [src/vsg/CMakeFiles/vsg.dir/vk/Uniform.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
CMakeFiles/Makefile2:277: recipe for target 'src/vsg/CMakeFiles/vsg.dir/all' failed
make[1]: *** [src/vsg/CMakeFiles/vsg.dir/all] Error 2
Makefile:129: recipe for target 'all' failed
make: *** [all] Error 2

[vsg-dev]

I have got it compiling with the follow change:
diff --git a/include/vsg/vk/Uniform.h b/include/vsg/vk/Uniform.h
index 503d125..91ee51d 100644
--- a/include/vsg/vk/Uniform.h
+++ b/include/vsg/vk/Uniform.h
@@ -95,13 +95,13 @@ namespace vsg
void read(Input& input) override
{
base_type::read(input);

•        input.read("Value", value());
  

•        input.read("Value", base_type::value());
     }
  
     void write(Output& output) const override
     {
         base_type::write(output);
  

•        output.write("Value", value());
  

•        output.write("Value", base_type::value());
     }
  

  };

I'll do a manual merge into new branch for the osg2vsg changes and play around with the new functionality.

[vsg-dev]

I have merged this PR and my change to the branch:

 https://github.com/vsg-dev/VulkanSceneGraphPrototype/tree/tomhog-topic-multitexturing-ii

I'll close this PR and work with the branch above.