main: Refactor _mesa_DrawBuffer.

This could have added a new DD table entry for DrawBuffer that takes an
arbitrary draw buffer, but, after looking at the existing DD functions,
Kenneth Graunke recommended that we just skip calling the DD functions in the
case of ARB_direct_state_access.  The DD implementations for DrawBuffer(s)
have limited functionality, especially with respect to
ARB_direct_state_access.

[Fredrik: Call the driver function when fb is the bound draw buffer]

Reviewed-by: Fredrik Höglund <[email protected]>
Signed-off-by: Fredrik Höglund <[email protected]>

1 files changed, 25 insertions, 17 deletions

diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index a338013fed5..8b52a5392a8 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -242,16 +242,16 @@ read_buffer_enum_to_index(GLenum buffer)
  *
  * See the GL_EXT_framebuffer_object spec for more info.
  */
-void GLAPIENTRY
-_mesa_DrawBuffer(GLenum buffer)
+void
+_mesa_draw_buffer(struct gl_context *ctx, struct gl_framebuffer *fb,
+                  GLenum buffer, const char *caller)
 {
    GLbitfield destMask;
-   GET_CURRENT_CONTEXT(ctx);
 
    FLUSH_VERTICES(ctx, 0);
 
    if (MESA_VERBOSE & VERBOSE_API) {
-      _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
+      _mesa_debug(ctx, "%s %s\n", caller, _mesa_lookup_enum_by_nr(buffer));
    }
 
    if (buffer == GL_NONE) {
@@ -259,33 +259,41 @@ _mesa_DrawBuffer(GLenum buffer)
    }
    else {
       const GLbitfield supportedMask
-         = supported_buffer_bitmask(ctx, ctx->DrawBuffer);
+         = supported_buffer_bitmask(ctx, fb);
       destMask = draw_buffer_enum_to_bitmask(ctx, buffer);
       if (destMask == BAD_MASK) {
          /* totally bogus buffer */
-         _mesa_error(ctx, GL_INVALID_ENUM,
-                     "glDrawBuffer(buffer=0x%x)", buffer);
+         _mesa_error(ctx, GL_INVALID_ENUM, "%s(invalid buffer %s)", caller,
+                     _mesa_lookup_enum_by_nr(buffer));
          return;
       }
       destMask &= supportedMask;
       if (destMask == 0x0) {
          /* none of the named color buffers exist! */
-         _mesa_error(ctx, GL_INVALID_OPERATION,
-                     "glDrawBuffer(buffer=0x%x)", buffer);
+         _mesa_error(ctx, GL_INVALID_OPERATION, "%s(invalid buffer %s)",
+                     caller, _mesa_lookup_enum_by_nr(buffer));
          return;
       }
    }
 
    /* if we get here, there's no error so set new state */
-   _mesa_drawbuffers(ctx, ctx->DrawBuffer, 1, &buffer, &destMask);
+   _mesa_drawbuffers(ctx, fb, 1, &buffer, &destMask);
+
+   /* Call device driver function only if fb is the bound draw buffer */
+   if (fb == ctx->DrawBuffer) {
+      if (ctx->Driver.DrawBuffers)
+         ctx->Driver.DrawBuffers(ctx, 1, &buffer);
+      else if (ctx->Driver.DrawBuffer)
+         ctx->Driver.DrawBuffer(ctx, buffer);
+   }
+}
 
-   /*
-    * Call device driver function.
-    */
-   if (ctx->Driver.DrawBuffers)
-      ctx->Driver.DrawBuffers(ctx, 1, &buffer);
-   else if (ctx->Driver.DrawBuffer)
-      ctx->Driver.DrawBuffer(ctx, buffer);
+
+void GLAPIENTRY
+_mesa_DrawBuffer(GLenum buffer)
+{
+   GET_CURRENT_CONTEXT(ctx);
+   _mesa_draw_buffer(ctx, ctx->DrawBuffer, buffer, "glDrawBuffer");
 }