[Mesa-dev] [PATCH 03/19] glsl: Refactor code for creating gl_PerVertex interface block.

[Paul Berry]

Currently, we create just a single gl_PerVertex interface block for
geometry shader inputs.  In later patches, we'll also need to create
an interface block for geometry and vertex shader outputs.  Moving the
code into its own class will make reuse easier.
---
 src/glsl/builtin_variables.cpp | 72 ++++++++++++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 23 deletions(-)

diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
index 91518ba..0ab7dda 100644
--- a/src/glsl/builtin_variables.cpp
+++ b/src/glsl/builtin_variables.cpp
@@ -293,6 +293,51 @@ static const struct gl_builtin_uniform_desc _mesa_builtin_uniform_desc[] = {
 
 namespace {
 
+/**
+ * Data structure that accumulates fields for the gl_PerVertex interface
+ * block.
+ */
+class per_vertex_accumulator
+{
+public:
+   per_vertex_accumulator();
+   void add_field(int slot, const glsl_type *type, const char *name);
+   const glsl_type *construct_interface_instance() const;
+
+private:
+   glsl_struct_field fields[10];
+   unsigned num_fields;
+};
+
+
+per_vertex_accumulator::per_vertex_accumulator()
+   : num_fields(0)
+{
+}
+
+
+void
+per_vertex_accumulator::add_field(int slot, const glsl_type *type,
+                                  const char *name)
+{
+   assert(this->num_fields < ARRAY_SIZE(this->fields));
+   this->fields[this->num_fields].type = type;
+   this->fields[this->num_fields].name = name;
+   this->fields[this->num_fields].row_major = false;
+   this->fields[this->num_fields].location = slot;
+   this->num_fields++;
+}
+
+
+const glsl_type *
+per_vertex_accumulator::construct_interface_instance() const
+{
+   return glsl_type::get_interface_instance(this->fields, this->num_fields,
+                                            GLSL_INTERFACE_PACKING_STD140,
+                                            "gl_PerVertex");
+}
+
+
 class builtin_variable_generator
 {
 public:
@@ -359,16 +404,7 @@ private:
    const glsl_type * const mat3_t;
    const glsl_type * const mat4_t;
 
-   /**
-    * Array where the contents of the gl_PerVertex interface instance are
-    * accumulated.
-    */
-   glsl_struct_field per_vertex_fields[10];
-
-   /**
-    * Number of elements of per_vertex_fields which have been populated.
-    */
-   unsigned num_per_vertex_fields;
+   per_vertex_accumulator per_vertex;
 };
 
 
@@ -379,8 +415,7 @@ builtin_variable_generator::builtin_variable_generator(
      bool_t(glsl_type::bool_type), int_t(glsl_type::int_type),
      float_t(glsl_type::float_type), vec2_t(glsl_type::vec2_type),
      vec3_t(glsl_type::vec3_type), vec4_t(glsl_type::vec4_type),
-     mat3_t(glsl_type::mat3_type), mat4_t(glsl_type::mat4_type),
-     num_per_vertex_fields(0)
+     mat3_t(glsl_type::mat3_type), mat4_t(glsl_type::mat4_type)
 {
 }
 
@@ -768,13 +803,7 @@ builtin_variable_generator::add_varying(int slot, const glsl_type *type,
 {
    switch (state->target) {
    case geometry_shader:
-      assert(this->num_per_vertex_fields <
-             ARRAY_SIZE(this->per_vertex_fields));
-      this->per_vertex_fields[this->num_per_vertex_fields].type = type;
-      this->per_vertex_fields[this->num_per_vertex_fields].name = name;
-      this->per_vertex_fields[this->num_per_vertex_fields].row_major = false;
-      this->per_vertex_fields[this->num_per_vertex_fields].location = slot;
-      this->num_per_vertex_fields++;
+      this->per_vertex.add_field(slot, type, name);
       /* FALLTHROUGH */
    case vertex_shader:
       add_output(slot, type, name);
@@ -824,10 +853,7 @@ builtin_variable_generator::generate_varyings()
 
    if (state->target == geometry_shader) {
       const glsl_type *per_vertex_type =
-         glsl_type::get_interface_instance(this->per_vertex_fields,
-                                           this->num_per_vertex_fields,
-                                           GLSL_INTERFACE_PACKING_STD140,
-                                           "gl_PerVertex");
+         this->per_vertex.construct_interface_instance();
       ir_variable *var = add_variable("gl_in", array(per_vertex_type, 0),
                                       ir_var_shader_in, -1);
       var->init_interface_type(per_vertex_type);
-- 
1.8.4