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-rw-r--r--src/mesa/drivers/dri/i965/brw_defines.h18
-rw-r--r--src/mesa/drivers/dri/i965/brw_sf_state.c28
2 files changed, 45 insertions, 1 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index 590b064c7e..74dbba4fdd 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -225,6 +225,24 @@
#define BRW_RASTRULE_UPPER_LEFT 0
#define BRW_RASTRULE_UPPER_RIGHT 1
+/* These are listed as "Reserved, but not seen as useful"
+ * in Intel documentation (page 212, "Point Rasterization Rule",
+ * section 7.4 "SF Pipeline State Summary", of document
+ * "Intel® 965 Express Chipset Family and Intel® G35 Express
+ * Chipset Graphics Controller Programmer's Reference Manual,
+ * Volume 2: 3D/Media", Revision 1.0b as of January 2008,
+ * available at
+ * http://intellinuxgraphics.org/documentation.html
+ * at the time of this writing).
+ *
+ * These appear to be supported on at least some
+ * i965-family devices, and the BRW_RASTRULE_LOWER_RIGHT
+ * is useful when using OpenGL to render to a FBO
+ * (which has the pixel coordinate Y orientation inverted
+ * with respect to the normal OpenGL pixel coordinate system).
+ */
+#define BRW_RASTRULE_LOWER_LEFT 2
+#define BRW_RASTRULE_LOWER_RIGHT 3
#define BRW_RENDERTARGET_CLAMPRANGE_UNORM 0
#define BRW_RENDERTARGET_CLAMPRANGE_SNORM 1
diff --git a/src/mesa/drivers/dri/i965/brw_sf_state.c b/src/mesa/drivers/dri/i965/brw_sf_state.c
index 93a9686f71..fc4eddda0a 100644
--- a/src/mesa/drivers/dri/i965/brw_sf_state.c
+++ b/src/mesa/drivers/dri/i965/brw_sf_state.c
@@ -231,7 +231,33 @@ sf_unit_create_from_key(struct brw_context *brw, struct brw_sf_unit_key *key,
sf.sf6.line_width = 0;
/* _NEW_POINT */
- sf.sf6.point_rast_rule = BRW_RASTRULE_UPPER_RIGHT; /* opengl conventions */
+ key->render_to_fbo = brw->intel.ctx.DrawBuffer->Name != 0;
+ if (!key->render_to_fbo) {
+ /* Rendering to an OpenGL window */
+ sf.sf6.point_rast_rule = BRW_RASTRULE_UPPER_RIGHT;
+ }
+ else {
+ /* If rendering to an FBO, the pixel coordinate system is
+ * inverted with respect to the normal OpenGL coordinate
+ * system, so BRW_RASTRULE_LOWER_RIGHT is correct.
+ * But this value is listed as "Reserved, but not seen as useful"
+ * in Intel documentation (page 212, "Point Rasterization Rule",
+ * section 7.4 "SF Pipeline State Summary", of document
+ * "Intel® 965 Express Chipset Family and Intel® G35 Express
+ * Chipset Graphics Controller Programmer's Reference Manual,
+ * Volume 2: 3D/Media", Revision 1.0b as of January 2008,
+ * available at
+ * http://intellinuxgraphics.org/documentation.html
+ * at the time of this writing).
+ *
+ * It does work on at least some devices, if not all;
+ * if devices that don't support it can be identified,
+ * the likely failure case is that points are rasterized
+ * incorrectly, which is no worse than occurs without
+ * the value, so we're using it here.
+ */
+ sf.sf6.point_rast_rule = BRW_RASTRULE_LOWER_RIGHT;
+ }
/* XXX clamp max depends on AA vs. non-AA */
sf.sf7.sprite_point = key->point_sprite;