[Mesa-dev] [RFC PATCH 21/56] glsl: Add tessellation shader defines and built-in variables.

[Ian Romanick]

On 09/20/2014 06:41 PM, Chris Forbes wrote:
> From: Fabian Bieler <fabianbieler at fastmail.fm>
> 
> ---
>  src/glsl/builtin_variables.cpp | 62 +++++++++++++++++++++++++++++++++++++++++-
>  src/glsl/glcpp/glcpp-parse.y   |  3 ++
>  2 files changed, 64 insertions(+), 1 deletion(-)
> 
> diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
> index 5b6f4ae..7ba0fe8 100644
> --- a/src/glsl/builtin_variables.cpp
> +++ b/src/glsl/builtin_variables.cpp
> @@ -343,6 +343,8 @@ public:
>     void generate_constants();
>     void generate_uniforms();
>     void generate_vs_special_vars();
> +   void generate_tcs_special_vars();
> +   void generate_tes_special_vars();
>     void generate_gs_special_vars();
>     void generate_fs_special_vars();
>     void generate_cs_special_vars();
> @@ -842,6 +844,40 @@ builtin_variable_generator::generate_vs_special_vars()
>  
>  
>  /**
> + * Generate variables which only exist in tessellation control shaders.
> + */
> +void
> +builtin_variable_generator::generate_tcs_special_vars()
> +{
> +   add_input(-1, int_t, "gl_PatchVerticesIn");
> +   add_input(VARYING_SLOT_PRIMITIVE_ID, int_t, "gl_PrimitiveID");// XXX: or sysval?
> +   add_system_value(SYSTEM_VALUE_INVOCATION_ID, int_t, "gl_InvocationID");
> +
> +   add_output(VARYING_SLOT_TESS_LEVEL_OUTER,
> +                    array(float_t, 4), "gl_TessLevelOuter");
> +   add_output(VARYING_SLOT_TESS_LEVEL_INNER,
> +                    array(float_t, 2), "gl_TessLevelInner");
> +}
> +
> +
> +/**
> + * Generate variables which only exist in tessellation evaluation shaders.
> + */
> +void
> +builtin_variable_generator::generate_tes_special_vars()
> +{
> +   add_input(-1, int_t, "gl_PatchVerticesIn");
> +   add_input(VARYING_SLOT_PRIMITIVE_ID, int_t, "gl_PrimitiveID");// XXX: or sysval?
> +   add_system_value(SYSTEM_VALUE_TESS_COORD, vec3_t, "gl_TessCoord");
> +
> +   add_input(VARYING_SLOT_TESS_LEVEL_OUTER,
> +                    array(float_t, 4), "gl_TessLevelOuter");
> +   add_input(VARYING_SLOT_TESS_LEVEL_INNER,
> +                    array(float_t, 2), "gl_TessLevelInner");
> +}
> +
> +
> +/**
>   * Generate variables which only exist in geometry shaders.
>   */
>  void
> @@ -964,6 +1000,9 @@ builtin_variable_generator::add_varying(int slot, const glsl_type *type,
>                                          const char *name_as_gs_input)
>  {
>     switch (state->stage) {
> +   case MESA_SHADER_TESS_CTRL:
> +   case MESA_SHADER_TESS_EVAL:
> +      // XXX: is this correct?
>     case MESA_SHADER_GEOMETRY:
>        this->per_vertex_in.add_field(slot, type, name);
>        /* FALLTHROUGH */
> @@ -1016,13 +1055,28 @@ builtin_variable_generator::generate_varyings()
>        }
>     }
>  
> +   if (state->stage == MESA_SHADER_TESS_CTRL ||
> +       state->stage == MESA_SHADER_TESS_EVAL) {
> +      const glsl_type *per_vertex_in_type =
> +         this->per_vertex_in.construct_interface_instance();
> +      add_variable("gl_in", array(per_vertex_in_type, state->Const.MaxPatchVertices),

This looks wrong, but I believe that it is correct.  Maybe add a spec
quotation?

    /* Section 7.1 (Built-In Language Variables) of the GLSL 4.00 spec
     * says:
     *
     *    "In the tessellation control language, built-in variables are
     *    intrinsically declared as:
     *
     *        in gl_PerVertex {
     *            vec4 gl_Position;
     *            float gl_PointSize;
     *            float gl_ClipDistance[];
     *        } gl_in[gl_MaxPatchVertices];"
     */

It may also be worth adding a similar quotation to the
MESA_SHADER_GEOMETRY case below.

> +                   ir_var_shader_in, -1);
> +   }
>     if (state->stage == MESA_SHADER_GEOMETRY) {
>        const glsl_type *per_vertex_in_type =
>           this->per_vertex_in.construct_interface_instance();
>        add_variable("gl_in", array(per_vertex_in_type, 0),
>                     ir_var_shader_in, -1);
>     }
> -   if (state->stage == MESA_SHADER_VERTEX || state->stage == MESA_SHADER_GEOMETRY) {
> +   if (state->stage == MESA_SHADER_TESS_CTRL) {
> +      const glsl_type *per_vertex_out_type =
> +         this->per_vertex_out.construct_interface_instance();
> +      add_variable("gl_out", array(per_vertex_out_type, 0),
> +                   ir_var_shader_out, -1);
> +   }
> +   if (state->stage == MESA_SHADER_VERTEX ||
> +       state->stage == MESA_SHADER_TESS_EVAL ||
> +       state->stage == MESA_SHADER_GEOMETRY) {
>        const glsl_type *per_vertex_out_type =
>           this->per_vertex_out.construct_interface_instance();
>        const glsl_struct_field *fields = per_vertex_out_type->fields.structure;
> @@ -1057,6 +1111,12 @@ _mesa_glsl_initialize_variables(exec_list *instructions,
>     case MESA_SHADER_VERTEX:
>        gen.generate_vs_special_vars();
>        break;
> +   case MESA_SHADER_TESS_CTRL:
> +      gen.generate_tcs_special_vars();
> +      break;
> +   case MESA_SHADER_TESS_EVAL:
> +      gen.generate_tes_special_vars();
> +      break;
>     case MESA_SHADER_GEOMETRY:
>        gen.generate_gs_special_vars();
>        break;
> diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
> index f1119eb..e0ec3b6 100644
> --- a/src/glsl/glcpp/glcpp-parse.y
> +++ b/src/glsl/glcpp/glcpp-parse.y
> @@ -2472,6 +2472,9 @@ _glcpp_parser_handle_version_declaration(glcpp_parser_t *parser, intmax_t versio
>  
>                if (extensions->ARB_derivative_control)
>                   add_builtin_define(parser, "GL_ARB_derivative_control", 1);
> +
> +	      if (extensions->ARB_tessellation_shader)
> +	         add_builtin_define(parser, "GL_ARB_tessellation_shader", 1);
>  	   }
>  	}
>  
>