gallium: add st_api feature mask to prevent advertising MS visuals

v2: use a define for the maximum sample count
v3: also test odd sample counts (r300 supports MS3)

While multisample renderbuffers are supported by mesa, MS visuals
are not, so we need a way to tell dri/st not to advertise them even
if the gallium driver does support multisampled surfaces.

Otherwise applications selecting these non-functional visuals would
run into trouble ...

Reviewed-by: Brian Paul <[email protected]>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/gallium/include/state_tracker/st_api.h b/src/gallium/include/state_tracker/st_api.h
index 3af1dfc6d4d..86ab02d2883 100644
--- a/src/gallium/include/state_tracker/st_api.h
+++ b/src/gallium/include/state_tracker/st_api.h
@@ -70,6 +70,17 @@ enum st_profile_type
 #define ST_PROFILE_OPENGL_ES2_MASK   (1 << ST_PROFILE_OPENGL_ES2)
 
 /**
+ * Optional API/state tracker features.
+ */
+enum st_api_feature
+{
+   ST_API_FEATURE_MS_VISUALS  /**< support for multisample visuals */
+};
+
+/* for feature_mask in st_api */
+#define ST_API_FEATURE_MS_VISUALS_MASK (1 << ST_API_FEATURE_MS_VISUALS)
+
+/**
  * New context flags for GL 3.0 and beyond.
  *
  * Profile information (core vs. compatibilty for OpenGL 3.2+) is communicated
@@ -430,6 +441,11 @@ struct st_api
    unsigned profile_mask;
 
    /**
+    * The supported optional features.  Tested with ST_FEATURE_*_MASK.
+    */
+   unsigned feature_mask;
+
+   /**
     * Destroy the API.
     */
    void (*destroy)(struct st_api *stapi);