[Mesa-dev] [PATCH 02/17] mesa: Track per-stage shader input and output limits independently

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

In OpenGL 3.2 these are independently queryable.  In addition, the spec
has different minimum-maximums for various values.
GL_MAX_VERTEX_OUTPUT_COMPONENTS is 64, but
GL_MAX_GEOMETRY_OUTPUT_COMPONENTS (and GL_MAX_FRAGMENT_INPUT_COMPONENTS)
is 128.

In OpenGL ES 3.0 these are also independently queryable.  The spec has
different minimum-maximums for various values.
GL_MAX_VERTEX_OUTPUT_VECTORS is 16, but GL_MAX_FRAGMENT_INTPUT_VECTORS
is 15.

None of these values are used yet.  I have just added space to the
structures.  Future patches will add users and eventually remove some
old fields.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: Paul Berry <stereotype441 at gmail.com>
Cc: Marek Olšák <maraeo at gmail.com>
Cc: Brian Paul <brianp at vmware.com>
Cc: Zack Rusin <zackr at vmware.com>
---
 src/mesa/main/mtypes.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index ca7111e..17bc31d 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2824,6 +2824,30 @@ struct gl_program_constants
    GLuint MaxNativeParameters;
    /* For shaders */
    GLuint MaxUniformComponents;  /**< Usually == MaxParameters * 4 */
+
+   /**
+    * \name Per-stage input / output limits
+    *
+    * Previous to OpenGL 3.2, the intrastage data limits were advertised with
+    * a single value: GL_MAX_VARYING_COMPONENTS (GL_MAX_VARYING_VECTORS in
+    * ES).  This is stored as \c gl_constants::MaxVarying.
+    *
+    * Starting with OpenGL 3.2, the limits are advertised with per-stage
+    * variables.  Each stage as a certain number of outputs that it can feed
+    * to the next stage and a certain number inputs that it can consume from
+    * the previous stage.
+    *
+    * Vertex shader inputs do not participate this in this accounting.
+    * These are tracked exclusively by \c gl_program_constants::MaxAttribs.
+    *
+    * Fragment shader outputs do not participate this in this accounting.
+    * These are tracked exclusively by \c gl_constants::MaxDrawBuffers.
+    */
+   /*@{*/
+   GLuint MaxInputComponents;
+   GLuint MaxOutputComponents;
+   /*@}*/
+
    /* ES 2.0 and GL_ARB_ES2_compatibility */
    struct gl_precision LowFloat, MediumFloat, HighFloat;
    struct gl_precision LowInt, MediumInt, HighInt;
-- 
1.8.1.4