[Mesa-dev] [PATCH 1/2] mesa: Add glsl_type::get_scalar_type() function.

[Kenneth Graunke]

On 10/25/2011 04:47 PM, Paul Berry wrote:
> This function is similar to get_base_type(), but when called on
> arrays, it returns the scalar type composing the array.  For example,
> glsl_type(vec4[]) => float_type.
> ---
>  src/glsl/glsl_types.cpp |   23 +++++++++++++++++++++++
>  src/glsl/glsl_types.h   |   11 +++++++++++
>  2 files changed, 34 insertions(+), 0 deletions(-)
> 
> diff --git a/src/glsl/glsl_types.cpp b/src/glsl/glsl_types.cpp
> index c94aec0..03e9987 100644
> --- a/src/glsl/glsl_types.cpp
> +++ b/src/glsl/glsl_types.cpp
> @@ -258,6 +258,29 @@ const glsl_type *glsl_type::get_base_type() const
>  }
>  
>  
> +const glsl_type *glsl_type::get_scalar_type() const
> +{
> +   const glsl_type *type = this;
> +
> +   /* Handle arrays */
> +   while (type->base_type == GLSL_TYPE_ARRAY)
> +      type = type->fields.array;

This is going to be a very short loop; in fact, it's actually equivalent to:

   if (type->base_type == GLSL_TYPE_ARRAY)
      type = type->fields.array;

since GLSL explicitly disallows arrays of arrays.  That said, it doesn't
really hurt anything, so I'm more observing this than objecting to the code.

> +   /* Handle vectors and matrices */
> +   switch (type->base_type) {
> +   case GLSL_TYPE_UINT:
> +      return uint_type;
> +   case GLSL_TYPE_INT:
> +      return int_type;
> +   case GLSL_TYPE_FLOAT:
> +      return float_type;
> +   default:
> +      /* Handle everything else */
> +      return type;
> +   }
> +}
> +
> +
>  void
>  _mesa_glsl_release_types(void)
>  {
> diff --git a/src/glsl/glsl_types.h b/src/glsl/glsl_types.h
> index 0486966..2f849af 100644
> --- a/src/glsl/glsl_types.h
> +++ b/src/glsl/glsl_types.h
> @@ -178,6 +178,17 @@ struct glsl_type {
>     const glsl_type *get_base_type() const;
>  
>     /**
> +    * Get the basic scalar type which this type aggregates.
> +    *
> +    * If the type is a numeric or boolean scalar, vector, or matrix, or an
> +    * array of any of those, this function gets the scalar type of the
> +    * individual components.  For structs and arrays of structs, this function
> +    * returns the struct type.  For samplers and arrays of samplers, this
> +    * function returns the sampler type.
> +    */
> +   const glsl_type *get_scalar_type() const;
> +
> +   /**
>      * Query the type of elements in an array
>      *
>      * \return