[Mesa-dev] [RFC 3/3] mesa: call DrawBuffer(s) driver hook in update_framebuffer for windows-system FB

[Timothy Arceri]

From: Boyan Ding <boyan.j.ding at gmail.com>

When draw buffers are changed on a bound framebuffer, DrawBuffer(s) hook
should be called. However, it is missing in update_framebuffer with
window-system framebuffer, in which FB's draw buffer state should match
context state, potentially resulting in a change.

Note: This seems to be needed because gallium delays creating the front
buffer. i965 works fine without this change.

V2 (Timothy Arceri):
 - Rebased on merged/simplified DrawBuffer driver function
 - Move DrawBuffer call outside fb->ColorDrawBuffer[0] !=
   ctx->Color.DrawBuffer[0] check to make piglit pass.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99116
---
 src/mesa/main/framebuffer.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
index 249e775f8cb..81d3b370e73 100644
--- a/src/mesa/main/framebuffer.c
+++ b/src/mesa/main/framebuffer.c
@@ -623,6 +623,12 @@ update_framebuffer(struct gl_context *ctx, struct gl_framebuffer *fb)
          _mesa_drawbuffers(ctx, fb, ctx->Const.MaxDrawBuffers,
                            ctx->Color.DrawBuffer, NULL);
       }
+
+      /* Call device driver function if fb is the bound draw buffer. */
+      if (fb == ctx->DrawBuffer) {
+         if (ctx->Driver.DrawBuffer)
+            ctx->Driver.DrawBuffer(ctx);
+      }
    }
    else {
       /* This is a user-created framebuffer.
-- 
2.17.0