mesa: implement GetMultisamplefv

Actual sample locations deferred to a driverfunc since only the driver
really knows where they will be.

V2: - pass the draw buffer to the driverfunc; don't fallback to pixel
      center if driverfunc is missing.
    - rename GetSampleLocation to GetSamplePosition
    - invert y sample position for winsys FBOs, at Paul's suggestion

Signed-off-by: Chris Forbes <[email protected]>
Reviewed-by: Paul Berry <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mesa/main/dd.h b/src/mesa/main/dd.h
index 9c818ccd86a..49071162617 100644
--- a/src/mesa/main/dd.h
+++ b/src/mesa/main/dd.h
@@ -833,6 +833,14 @@ struct dd_function_table {
     * This should be equivalent to glGetInteger64v(GL_TIMESTAMP);
     */
    uint64_t (*GetTimestamp)(struct gl_context *ctx);
+
+   /**
+    * \name GL_ARB_texture_multisample
+    */
+   void (*GetSamplePosition)(struct gl_context *ctx,
+                             struct gl_framebuffer *fb,
+                             GLuint index,
+                             GLfloat *outValue);
 };