glsl: Distinguish between no interpolation qualifier and 'smooth'

Previously, we treated the 'smooth' qualifier as equivalent to no
qualifier at all.  However, this is incorrect for the built-in color
variables (gl_FrontColor, gl_BackColor, gl_FrontSecondaryColor, and
gl_BackSecondaryColor).  For those variables, if there is no qualifier
at all, interpolation should be flat if the shade model is GL_FLAT,
and smooth if the shade model is GL_SMOOTH.

To make this possible, I added a new value to the
glsl_interp_qualifier enum, INTERP_QUALIFIER_NONE.

Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 9410e3ff67a..aa3fa6aecf0 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -1793,9 +1793,13 @@ typedef enum
 /**
  * The possible interpolation qualifiers that can be applied to a fragment
  * shader input in GLSL.
+ *
+ * Note: INTERP_QUALIFIER_NONE must be 0 so that memsetting the
+ * gl_fragment_program data structure to 0 causes the default behavior.
  */
 enum glsl_interp_qualifier
 {
+   INTERP_QUALIFIER_NONE = 0,
    INTERP_QUALIFIER_SMOOTH,
    INTERP_QUALIFIER_FLAT,
    INTERP_QUALIFIER_NOPERSPECTIVE
@@ -1906,7 +1910,7 @@ struct gl_fragment_program
    /**
     * GLSL interpolation qualifier associated with each fragment shader input.
     * For inputs that do not have an interpolation qualifier specified in
-    * GLSL, the value is INTERP_QUALIFIER_SMOOTH.
+    * GLSL, the value is INTERP_QUALIFIER_NONE.
     */
    enum glsl_interp_qualifier InterpQualifier[FRAG_ATTRIB_MAX];
 };