tgsi: add caps for fragment coord conventions (v3)

Changes in v3:
- Renumber caps to accomodate caps to add to master in the meantime
- Document caps
- Add unsupported caps to *_screen.c too

Changes in v2:
- Split for properties patch
- Use positive caps instead of negative caps

This adds 4 caps to indicate support of each of the fragment coord
conventions.

All drivers are also modifed to add the appropriate caps.

Some drivers were incorrectly using non-Gallium-default conventions,
and caps for them have them set so that they will behave correctly
after the later state tracker patches.

This drivers are softpipe/llvmpipe (uses integer rather than half
integer) and pre-nv50 Nouveau (uses lower left rather than upper left).

Other drivers might be broken. With this patchset, fixing them is
only a matter of exposing the appropriate caps that match the behavior
of the existing code.

Drivers are encouraged to support all conventions themselves for better
performance, and this feature is added to softpipe in a later patch.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/gallium/drivers/nv20/nv20_screen.c b/src/gallium/drivers/nv20/nv20_screen.c
index 7782cbe3a8e..df9401bcce0 100644
--- a/src/gallium/drivers/nv20/nv20_screen.c
+++ b/src/gallium/drivers/nv20/nv20_screen.c
@@ -44,6 +44,12 @@ nv20_screen_get_param(struct pipe_screen *screen, int param)
 		return 0;
 	case PIPE_CAP_INDEP_BLEND_FUNC:
 		return 0;
+	case PIPE_CAP_TGSI_FS_COORD_ORIGIN_LOWER_LEFT:
+	case PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_HALF_INTEGER:
+		return 1;
+	case PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT:
+	case PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_INTEGER:
+		return 0;
 	default:
 		NOUVEAU_ERR("Unknown PIPE_CAP %d\n", param);
 		return 0;