mesa: add comments and change Index2D to just Index2

1 files changed, 13 insertions, 3 deletions

diff --git a/src/mesa/program/prog_instruction.h b/src/mesa/program/prog_instruction.h
index cb5beb9b00..dacbc33704 100644
--- a/src/mesa/program/prog_instruction.h
+++ b/src/mesa/program/prog_instruction.h
@@ -272,9 +272,19 @@ struct prog_src_register
     */
    GLuint Negate:4;
 
-   GLuint HasIndex2D:1;
-   GLuint RelAddr2D:1;
-   GLint Index2D:(INST_INDEX_BITS+1); /**< Extra bit here for sign bit.
+   /**
+    * Is the register two-dimensional.
+    * Two dimensional registers are of the
+    * REGISTER[index][index2] format.
+    * They are used by the geometry shaders where
+    * the first index is the index within an array
+    * and the second index is the semantic of the
+    * array, e.g. gl_PositionIn[index] would become
+    * INPUT[index][gl_PositionIn]
+    */
+   GLuint HasIndex2:1;
+   GLuint RelAddr2:1;
+   GLint Index2:(INST_INDEX_BITS+1); /**< Extra bit here for sign bit.
                                        * May be negative for relative
                                        * addressing. */
 };