5 files changed, 49 insertions, 0 deletions

diff --git a/mesalib/src/mesa/program/prog_print.c b/mesalib/src/mesa/program/prog_print.c
index cf852132d..fa9063f5b 100644
--- a/mesalib/src/mesa/program/prog_print.c
+++ b/mesalib/src/mesa/program/prog_print.c
@@ -311,6 +311,7 @@ arb_output_attrib_string(GLint index, GLenum progType)
       "result.depth", /* FRAG_RESULT_DEPTH */
       "result.(one)", /* FRAG_RESULT_STENCIL */
       "result.color", /* FRAG_RESULT_COLOR */
+      "result.samplemask", /* FRAG_RESULT_SAMPLE_MASK */
       "result.color[0]", /* FRAG_RESULT_DATA0 (named for GLSL's gl_FragData) */
       "result.color[1]",
       "result.color[2]",
diff --git a/mesalib/src/mesa/program/prog_statevars.c b/mesalib/src/mesa/program/prog_statevars.c
index 145c07c67..f6fd53576 100644
--- a/mesalib/src/mesa/program/prog_statevars.c
+++ b/mesalib/src/mesa/program/prog_statevars.c
@@ -349,6 +349,9 @@ _mesa_fetch_state(struct gl_context *ctx, const gl_state_index state[],
          }
       }
       return;
+   case STATE_NUM_SAMPLES:
+      ((int *)value)[0] = ctx->DrawBuffer->Visual.samples;
+      return;
    case STATE_DEPTH_RANGE:
       value[0] = ctx->Viewport.Near;                     /* near       */
       value[1] = ctx->Viewport.Far;                      /* far        */
@@ -665,6 +668,9 @@ _mesa_program_state_flags(const gl_state_index state[STATE_LENGTH])
    case STATE_PROGRAM_MATRIX:
       return _NEW_TRACK_MATRIX;
 
+   case STATE_NUM_SAMPLES:
+      return _NEW_BUFFERS;
+
    case STATE_DEPTH_RANGE:
       return _NEW_VIEWPORT;
 
@@ -852,6 +858,9 @@ append_token(char *dst, gl_state_index k)
    case STATE_TEXENV_COLOR:
       append(dst, "texenv");
       break;
+   case STATE_NUM_SAMPLES:
+      append(dst, "numsamples");
+      break;
    case STATE_DEPTH_RANGE:
       append(dst, "depth.range");
       break;
@@ -1027,6 +1036,8 @@ _mesa_program_state_string(const gl_state_index state[STATE_LENGTH])
       break;
    case STATE_FOG_COLOR:
       break;
+   case STATE_NUM_SAMPLES:
+      break;
    case STATE_DEPTH_RANGE:
       break;
    case STATE_FRAGMENT_PROGRAM:
diff --git a/mesalib/src/mesa/program/prog_statevars.h b/mesalib/src/mesa/program/prog_statevars.h
index ec22b7376..23a9f48c3 100644
--- a/mesalib/src/mesa/program/prog_statevars.h
+++ b/mesalib/src/mesa/program/prog_statevars.h
@@ -103,6 +103,8 @@ typedef enum gl_state_index_ {
 
    STATE_TEXENV_COLOR,
 
+   STATE_NUM_SAMPLES,    /* An integer, not a float like the other state vars */
+
    STATE_DEPTH_RANGE,
 
    STATE_VERTEX_PROGRAM,
diff --git a/mesalib/src/mesa/program/program.c b/mesalib/src/mesa/program/program.c
index 093d37297..a102ec17a 100644
--- a/mesalib/src/mesa/program/program.c
+++ b/mesalib/src/mesa/program/program.c
@@ -32,6 +32,7 @@
 #include "main/glheader.h"
 #include "main/context.h"
 #include "main/hash.h"
+#include "main/macros.h"
 #include "program.h"
 #include "prog_cache.h"
 #include "prog_parameter.h"
@@ -1024,3 +1025,34 @@ _mesa_postprocess_program(struct gl_context *ctx, struct gl_program *prog)
 
    }
 }
+
+/* Gets the minimum number of shader invocations per fragment.
+ * This function is useful to determine if we need to do per
+ * sample shading or per fragment shading.
+ */
+GLint
+_mesa_get_min_invocations_per_fragment(struct gl_context *ctx,
+                                       const struct gl_fragment_program *prog)
+{
+   /* From ARB_sample_shading specification:
+    * "Using gl_SampleID in a fragment shader causes the entire shader
+    *  to be evaluated per-sample."
+    *
+    * "Using gl_SamplePosition in a fragment shader causes the entire
+    *  shader to be evaluated per-sample."
+    *
+    * "If MULTISAMPLE or SAMPLE_SHADING_ARB is disabled, sample shading
+    *  has no effect."
+    */
+   if (ctx->Multisample.Enabled) {
+      if (prog->Base.SystemValuesRead & (SYSTEM_BIT_SAMPLE_ID |
+                                         SYSTEM_BIT_SAMPLE_POS))
+         return MAX2(ctx->DrawBuffer->Visual.samples, 1);
+      else if (ctx->Multisample.SampleShading)
+         return MAX2(ceil(ctx->Multisample.MinSampleShadingValue *
+                          ctx->DrawBuffer->Visual.samples), 1);
+      else
+         return 1;
+   }
+   return 1;
+}
diff --git a/mesalib/src/mesa/program/program.h b/mesalib/src/mesa/program/program.h
index 34965ab99..353ccab47 100644
--- a/mesalib/src/mesa/program/program.h
+++ b/mesalib/src/mesa/program/program.h
@@ -187,6 +187,9 @@ _mesa_valid_register_index(const struct gl_context *ctx,
 extern void
 _mesa_postprocess_program(struct gl_context *ctx, struct gl_program *prog);
 
+extern GLint
+_mesa_get_min_invocations_per_fragment(struct gl_context *ctx,
+                                       const struct gl_fragment_program *prog);
 
 static inline GLuint
 _mesa_program_target_to_index(GLenum v)