i965: fix polygon face orientation when rendering to FBO

In the i965, the FBO coordinate system is inverted from the standard
OpenGL/Mesa coordinate system; that means that the viewport and the
polygon face orientation have to be inverted if rendering to a FBO.

The viewport was already being handled correctly; but polygon face
was not.  This caused a conform failure when rendering to texture with
two-sided lighting enabled.

This fixes the problem in the i965 driver, and adds to the comment about
the gl_framebuffer "Name" field so that this isn't a surprise to other
driver writers.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index f2058641911..9080c83da4e 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2236,7 +2236,15 @@ struct gl_renderbuffer_attachment
 struct gl_framebuffer
 {
    _glthread_Mutex Mutex;  /**< for thread safety */
-   GLuint Name;            /**< if zero, this is a window system framebuffer */
+   /**
+    * If zero, this is a window system framebuffer.  If non-zero, this
+    * is a FBO framebuffer; note that for some devices (i.e. those with
+    * a natural pixel coordinate system for FBOs that differs from the 
+    * OpenGL/Mesa coordinate system), this means that both the viewport
+    * and polygon face orientation will have to be inverted.
+    */
+   GLuint Name;
+
    GLint RefCount;
    GLboolean DeletePending;