- Restored "dither" option for conversion from float -> byte images.

  This now is a post-process option only (used to be in render).
  It is only handled within the Imbuf/ module, on conversions from float
  to byte rect, which atm mostly happens on saving images.

- Small fix: when using Scene RenderLayer nodes, the speed vectors for
  these nodes were not created when that scene had "Do Composite" off.

2 files changed, 31 insertions, 9 deletions

diff --git a/source/blender/imbuf/IMB_imbuf_types.h b/source/blender/imbuf/IMB_imbuf_types.h
index fe82b852eaa..db178841979 100644
--- a/source/blender/imbuf/IMB_imbuf_types.h
+++ b/source/blender/imbuf/IMB_imbuf_types.h
@@ -96,7 +96,8 @@ typedef struct ImBuf{
 	unsigned int   encodedbuffersize; /**< Size of encodedbuffer */
 
 	float *rect_float;		/**< floating point Rect equivilant */
-
+	float dither;			/**< random dither value, for conversion from float -> byte rect */
+	
 	struct MEM_CacheLimiterHandle_s * c_handle; /**< handle for cache limiter */
 	int refcounter;                /**< Refcounter for multiple users */
 } ImBuf;
diff --git a/source/blender/imbuf/intern/divers.c b/source/blender/imbuf/intern/divers.c
index 71292e27611..2fc80f6ddcb 100644
--- a/source/blender/imbuf/intern/divers.c
+++ b/source/blender/imbuf/intern/divers.c
@@ -33,6 +33,7 @@
  */
 
 #include "BLI_blenlib.h"
+#include "BLI_rand.h"
 
 #include "imbuf.h"
 #include "imbuf_patch.h"
@@ -172,6 +173,7 @@ void IMB_rect_from_float(struct ImBuf *ibuf)
 {
 	/* quick method to convert floatbuf to byte */
 	float *tof = ibuf->rect_float;
+	float dither= ibuf->dither;
 	int i;
 	unsigned char *to = (unsigned char *) ibuf->rect;
 	
@@ -181,14 +183,33 @@ void IMB_rect_from_float(struct ImBuf *ibuf)
 		to = (unsigned char *) ibuf->rect;
 	}
 	
-	for (i = ibuf->x * ibuf->y; i > 0; i--) 
-	{
-		to[0] = FTOCHAR(tof[0]);
-		to[1] = FTOCHAR(tof[1]);
-		to[2] = FTOCHAR(tof[2]);
-		to[3] = FTOCHAR(tof[3]);
-		to += 4; 
-		tof += 4;
+	if(dither==0.0f) {
+		for (i = ibuf->x * ibuf->y; i > 0; i--) {
+			to[0] = FTOCHAR(tof[0]);
+			to[1] = FTOCHAR(tof[1]);
+			to[2] = FTOCHAR(tof[2]);
+			to[3] = FTOCHAR(tof[3]);
+			to += 4; 
+			tof += 4;
+		}
+	}
+	else {
+		float dither_value, col;
+		dither= dither/255.0f;
+		for (i = ibuf->x * ibuf->y; i > 0; i--) {
+			dither_value = (BLI_frand()-0.5)*dither; 
+			col= tof[0] + dither_value;
+			to[0] = FTOCHAR(col);
+			col= tof[1] + dither_value;
+			to[1] = FTOCHAR(col);
+			col= tof[2] + dither_value;
+			to[2] = FTOCHAR(col);
+			col= tof[3] + dither_value;
+			to[3] = FTOCHAR(col);
+
+			to += 4; 
+			tof += 4;
+		}
 	}
 }