mesa: Rename MESA_shader_framebuffer_fetch gl_extensions bits to EXT.

[mesa.git] / src / mesa / drivers / dri / i965 / brw_multisample_state.h

diff --git a/src/mesa/drivers/dri/i965/brw_multisample_state.h b/src/mesa/drivers/dri/i965/brw_multisample_state.h
index 2e0250004da5f25a629cc26bcad9d8d23bc8cc47..6cf324e561c14a30a1911d671f4025d5ec86c8d6 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_multisample_state.h
+++ b/src/mesa/drivers/dri/i965/brw_multisample_state.h
@@ -21,8 +21,31 @@
  * IN THE SOFTWARE.
  */
 
+#ifndef BRW_MULTISAMPLE_STATE_H
+#define BRW_MULTISAMPLE_STATE_H
+
 #include <stdint.h>
 
+/**
+ * Note: There are no standard multisample positions defined in OpenGL
+ * specifications. Implementations have the freedom to pick the positions
+ * which give plausible results. But the Vulkan specification does define
+ * standard sample positions. So, we decided to pick the same pattern in
+ * OpenGL as in Vulkan to keep it uniform across drivers and also to avoid
+ * breaking applications which rely on this standard pattern.
+ */
+
+/**
+ * 1x MSAA has a single sample at the center: (0.5, 0.5) -> (0x8, 0x8).
+ *
+ * 2x MSAA sample positions are (0.25, 0.25) and (0.75, 0.75):
+ *   4 c
+ * 4 0
+ * c   1
+ */
+static const uint32_t
+brw_multisample_positions_1x_2x = 0x0088cc44;
+
 /**
  * Sample positions:
  *   2 6 a e
@@ -35,22 +58,10 @@ static const uint32_t
 brw_multisample_positions_4x = 0xae2ae662;
 
 /**
- * Sample positions are based on a solution to the "8 queens" puzzle.
- * Rationale: in a solution to the 8 queens puzzle, no two queens share
- * a row, column, or diagonal.  This is a desirable property for samples
- * in a multisampling pattern, because it ensures that the samples are
- * relatively uniformly distributed through the pixel.
- *
- * There are several solutions to the 8 queens puzzle (see
- * http://en.wikipedia.org/wiki/Eight_queens_puzzle).  This solution was
- * chosen because it has a queen close to the center; this should
- * improve the accuracy of centroid interpolation, since the hardware
- * implements centroid interpolation by choosing the centermost sample
- * that overlaps with the primitive being drawn.
+ * Sample positions:
  *
- * Note: from the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
+ * From the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
  * Programming Notes):
- *
  *     "When programming the sample offsets (for NUMSAMPLES_4 or _8 and
  *     MSRASTMODE_xxx_PATTERN), the order of the samples 0 to 3 (or 7
  *     for 8X) must have monotonically increasing distance from the
@@ -59,14 +70,42 @@ brw_multisample_positions_4x = 0xae2ae662;
  *
  * Sample positions:
  *   1 3 5 7 9 b d f
- * 1     5
- * 3           2
- * 5               6
- * 7 4
- * 9       0
- * b             3
- * d         1
- * f   7
+ * 1               7
+ * 3     3
+ * 5         0
+ * 7 5
+ * 9             2
+ * b       1
+ * d   4
+ * f           6
  */
 static const uint32_t
-brw_multisample_positions_8x[] = { 0xdbb39d79, 0x3ff55117 };
+brw_multisample_positions_8x[] = { 0x53d97b95, 0xf1bf173d };
+
+/**
+ * Sample positions:
+ *
+ *    0 1 2 3 4 5 6 7 8 9 a b c d e f
+ * 0   15
+ * 1                  9
+ * 2         10
+ * 3                        7
+ * 4                               13
+ * 5                1
+ * 6        4
+ * 7                          3
+ * 8 12
+ * 9                    0
+ * a            2
+ * b                            6
+ * c     11
+ * d                      5
+ * e              8
+ * f                             14
+ */
+static const uint32_t
+brw_multisample_positions_16x[] = {
+   0xc75a7599, 0xb3dbad36, 0x2c42816e, 0x10eff408
+};
+
+#endif /* BRW_MULTISAMPLE_STATE_H */