[Mesa-dev] [PATCH 2/8] glsl: add ir_variable::determine_interpolation_mode() function.

[Paul Berry]

This function determines how a variable should be interpolated based
both on interpolation qualifiers and the current shade model.
---
 src/glsl/ir.cpp |   15 +++++++++++++++
 src/glsl/ir.h   |   11 +++++++++++
 2 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index a833c80..0b5c35a 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1354,6 +1354,21 @@ ir_variable::interpolation_string() const
 }
 
 
+ir_variable_interpolation
+ir_variable::determine_interpolation_mode(bool flat_shade)
+{
+   if (this->interpolation != ir_var_interp_unspecified)
+      return (ir_variable_interpolation) this->interpolation;
+   int location = this->location;
+   bool is_gl_Color =
+      location == FRAG_ATTRIB_COL0 || location == FRAG_ATTRIB_COL1;
+   if (flat_shade && is_gl_Color)
+      return ir_var_interp_flat;
+   else
+      return ir_var_interp_smooth;
+}
+
+
 ir_function_signature::ir_function_signature(const glsl_type *return_type)
    : return_type(return_type), is_defined(false), _function(NULL)
 {
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index e8ce28d..6262369 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -298,6 +298,17 @@ public:
    const char *interpolation_string() const;
 
    /**
+    * Determine how this variable should be interpolated based on its
+    * interpolation qualifier (if present), whether it is gl_Color or
+    * gl_SecondaryColor, and whether flatshading is enabled in the current GL
+    * state.
+    *
+    * The return value will always be either ir_var_interp_smooth,
+    * ir_var_interp_noperspective, or ir_var_interp_flat.
+    */
+   ir_variable_interpolation determine_interpolation_mode(bool flat_shade);
+
+   /**
     * Delcared name of the variable
     */
    const char *name;
-- 
1.7.6.4