3 files changed, 21 insertions, 0 deletions
diff --git a/src/mesa/swrast/s_context.c b/src/mesa/swrast/s_context.c
index 186fda0949f..9d283b0589e 100644
--- a/src/mesa/swrast/s_context.c
+++ b/src/mesa/swrast/s_context.c
@@ -105,6 +105,12 @@ _swrast_update_rasterflags( GLcontext *ctx )
       rasterMask |= ATIFRAGSHADER_BIT;
    }
 
+#if CHAN_TYPE == GL_FLOAT
+   if (ctx->Color.ClampFragmentColor == GL_TRUE) {
+      rasterMask |= CLAMPING_BIT;
+   }
+#endif
+
    SWRAST_CONTEXT(ctx)->_RasterMask = rasterMask;
 }
 
diff --git a/src/mesa/swrast/s_context.h b/src/mesa/swrast/s_context.h
index 3d738819e94..5cfe7627a5d 100644
--- a/src/mesa/swrast/s_context.h
+++ b/src/mesa/swrast/s_context.h
@@ -245,6 +245,7 @@ typedef void (*swrast_tri_func)( GLcontext *ctx, const SWvertex *,
 #define TEXTURE_BIT		0x1000	/**< Texturing really enabled */
 #define FRAGPROG_BIT            0x2000  /**< Fragment program enabled */
 #define ATIFRAGSHADER_BIT       0x4000  /**< ATI Fragment shader enabled */
+#define CLAMPING_BIT            0x8000  /**< Clamp colors to [0,1] */
 /*@}*/
 
 #define _SWRAST_NEW_RASTERMASK (_NEW_BUFFERS|	\
diff --git a/src/mesa/swrast/s_span.c b/src/mesa/swrast/s_span.c
index fbff31b90e3..1cf743ae483 100644
--- a/src/mesa/swrast/s_span.c
+++ b/src/mesa/swrast/s_span.c
@@ -1276,6 +1276,20 @@ _swrast_write_rgba_span( GLcontext *ctx, struct sw_span *span)
       }
    }
 
+   /* Clamp color/alpha values over the range [0.0, 1.0] before storage */
+#if CHAN_TYPE == GL_FLOAT
+   if (ctx->Color.ClampFragmentColor) {
+      GLchan (*rgba)[4] = span->array->rgba;
+      GLuint i;
+      for (i = 0; i < span->end; i++) {
+         rgba[i][RCOMP] = CLAMP(rgba[i][RCOMP], 0.0, CHAN_MAXF);
+         rgba[i][GCOMP] = CLAMP(rgba[i][GCOMP], 0.0, CHAN_MAXF);
+         rgba[i][BCOMP] = CLAMP(rgba[i][BCOMP], 0.0, CHAN_MAXF);
+         rgba[i][ACOMP] = CLAMP(rgba[i][ACOMP], 0.0, CHAN_MAXF);
+      }
+   }
+#endif
+
    if (swrast->_RasterMask & MULTI_DRAW_BIT) {
       /* need to do blend/logicop separately for each color buffer */
       multi_write_rgba_span(ctx, span);