uniform keyword in HLSL

it seems that in HLSL i can but dont have t开发者_JAVA技巧o provide the uniform keyword for variables which come from the application. right?

why is that so?

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In HLSL global variables are considered uniform by default.

It's also settled that a variable coming out of the vertex shader stage for example is varying (HLSL doesn't need this keyword at all!).

Note that GLSL keywords uniform/varying are inherited from RSL (RenderMan shading language).