[Mesa-dev] [PATCH] glsl: do not emit error for non written varyings on OpenGL ES

[Tapani Pälli]

Patch fixes following test case from 'shaders-with-varyings' WebGL
conformance suite: "vertex shader with unused varying and fragment
shader with used varying must succeed"

Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
---
 src/glsl/link_varyings.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
index 54ceae1..fb2d88c 100644
--- a/src/glsl/link_varyings.cpp
+++ b/src/glsl/link_varyings.cpp
@@ -1451,7 +1451,7 @@ assign_varying_locations(struct gl_context *ctx,
 
          if (var && var->data.mode == ir_var_shader_in &&
              var->data.is_unmatched_generic_inout) {
-            if (prog->Version <= 120) {
+            if (prog->Version <= 120 && !prog->IsES) {
                /* On page 25 (page 31 of the PDF) of the GLSL 1.20 spec:
                 *
                 *     Only those varying variables used (i.e. read) in
@@ -1463,6 +1463,16 @@ assign_varying_locations(struct gl_context *ctx,
                 * We interpret this text as meaning that the VS must
                 * write the variable for the FS to read it.  See
                 * "glsl1-varying read but not written" in piglit.
+                *
+                * Note that this is not an error on OpenGL ES:
+                *
+                * On Page 91 (Page 97 of the PDF) of the GLSL ES 1.0 spec:
+                *
+                *     If the vertex shader declares but doesn't write to a
+                *     varying and the fragment shader declares and reads it,
+                *     is this and error?
+                *
+                *     RESOLUTION: No.
                 */
 
                linker_error(prog, "%s shader varying %s not written "
-- 
1.9.3