wflinfo: add GLSL version information to wflinfo

For versions that do not provide a shader version (GL ES 1.x, GL < 2.0)
print "None", otherwise print the value of GL_SHADING_LANGUAGE_VERSION.

None was picked because it is simple, obvious, and unlike N/A can't be
expanded into multiple meanings

v2: - Don't print for gles1, since gles1 doesn't have a shading language
      and will always return FLINFO_GL_ERROR
v3: - Print 'None' for GL ES 1.x and GL < 2.0
    - Only print shader_version in verbose mode

Fixes: https://github.com/waffle-gl/waffle/issues/16
Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/src/utils/wflinfo.c b/src/utils/wflinfo.c
index c2af4dc..6e34c15 100644
--- a/src/utils/wflinfo.c
+++ b/src/utils/wflinfo.c
@@ -209,6 +209,7 @@ enum {
     GL_VERSION                             = 0x1F02,
     GL_EXTENSIONS                          = 0x1F03,
     GL_NUM_EXTENSIONS                      = 0x821D,
+    GL_SHADING_LANGUAGE_VERSION            = 0x8B8C,
 };
 
 #define WINDOW_WIDTH  320
@@ -574,8 +575,25 @@ print_wflinfo(const struct options *opts)
     if (!glGetStringi && use_getstringi)
         error_get_gl_symbol("glGetStringi");
 
-    if (opts->verbose)
+    if (opts->verbose) {
+        // There are two exceptional cases where wflinfo may not get a
+        // version (or a valid version): one is in gles1 and the other
+        // is GL < 2.0. In these cases do not return WFLINFO_GL_ERROR,
+        // return None. This is preferable to returning WFLINFO_GL_ERROR
+        // because it creates a consistant interface for parsers
+        const char *language_str = "None";
+        if ((opts->context_api == WAFFLE_CONTEXT_OPENGL && version >= 20) ||
+                opts->context_api == WAFFLE_CONTEXT_OPENGL_ES2 ||
+                opts->context_api == WAFFLE_CONTEXT_OPENGL_ES3) {
+            language_str = (const char *) glGetString(GL_SHADING_LANGUAGE_VERSION);
+            if (glGetError() != GL_NO_ERROR || language_str == NULL) {
+                language_str = "WFLINFO_GL_ERROR";
+            }
+        }
+
+        printf("OpenGL shading language version string: %s\n", language_str);
         print_extensions(use_getstringi);
+    }
 
     return true;
 }