Fix [#22082] World gradients look like poo

(nice)

Added dither support to in-progress render float->byte conversions.

diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index 47dd95eb17bbeb8a1223fea8b82327d7c77d09c4..b699ec1abc53d5dfc5d870ed9d95ebf4d923893b 100644 (file)
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -33,6 +33,7 @@
 #include "BLI_blenlib.h"
 #include "BLI_math.h"
 #include "BLI_threads.h"
+#include "BLI_rand.h"
 
 #include "DNA_scene_types.h"
 
@@ -131,23 +132,25 @@ void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, volat
 
        if(ibuf->rect==NULL)
                imb_addrectImBuf(ibuf);
-
+       
        rectf+= 4*(rr->rectx*ymin + xmin);
        rectc= (char *)(ibuf->rect + ibuf->x*rymin + rxmin);
-
+       
        /* XXX make nice consistent functions for this */
        if (scene && (scene->r.color_mgt_flag & R_COLOR_MANAGEMENT)) {
                for(y1= 0; y1<ymax; y1++) {
                        float *rf= rectf;
                        float srgb[3];
                        char *rc= rectc;
+                       const float dither = ibuf->dither / 255.0;
 
                        /* XXX temp. because crop offset */
                        if( rectc >= (char *)(ibuf->rect)) {
                                for(x1= 0; x1<xmax; x1++, rf += 4, rc+=4) {
-                                       srgb[0]= linearrgb_to_srgb(rf[0]);
-                                       srgb[1]= linearrgb_to_srgb(rf[1]);
-                                       srgb[2]= linearrgb_to_srgb(rf[2]);
+                                       const float d = (BLI_frand()-0.5)*dither;
+                                       srgb[0]= d + linearrgb_to_srgb(rf[0]);
+                                       srgb[1]= d + linearrgb_to_srgb(rf[1]);
+                                       srgb[2]= d + linearrgb_to_srgb(rf[2]);
 
                                        rc[0]= FTOCHAR(srgb[0]);
                                        rc[1]= FTOCHAR(srgb[1]);
@@ -162,20 +165,28 @@ void image_buffer_rect_update(Scene *scene, RenderResult *rr, ImBuf *ibuf, volat
                for(y1= 0; y1<ymax; y1++) {
                        float *rf= rectf;
                        char *rc= rectc;
+                       float rgb[3];
+                       const float dither = ibuf->dither / 255.0;
 
                        /* XXX temp. because crop offset */
                        if( rectc >= (char *)(ibuf->rect)) {
                                for(x1= 0; x1<xmax; x1++, rf += 4, rc+=4) {
-                                       rc[0]= FTOCHAR(rf[0]);
-                                       rc[1]= FTOCHAR(rf[1]);
-                                       rc[2]= FTOCHAR(rf[2]);
+                                       const float d = (BLI_frand()-0.5)*dither;
+                                       
+                                       rgb[0] = d + rf[0];
+                                       rgb[1] = d + rf[1];
+                                       rgb[2] = d + rf[2];
+                                       
+                                       rc[0]= FTOCHAR(rgb[0]);
+                                       rc[1]= FTOCHAR(rgb[1]);
+                                       rc[2]= FTOCHAR(rgb[2]);
                                        rc[3]= FTOCHAR(rf[3]);
                                }
                        }
                        rectf += 4*rr->rectx;
                        rectc += 4*ibuf->x;
                }
-       }
+       }       
 }
 
 /* new window uses x,y to set position */