Fix T78956: banding artifacts of vertex colors in Cycles

Byte colors must be encoded in sRGB and converted to linear on lookup,
to avoid precision loss.

1 files changed, 5 insertions, 4 deletions

diff --git a/intern/cycles/blender/blender_mesh.cpp b/intern/cycles/blender/blender_mesh.cpp
index e40e1f5f001..b78a2c30b5e 100644
--- a/intern/cycles/blender/blender_mesh.cpp
+++ b/intern/cycles/blender/blender_mesh.cpp
@@ -346,7 +346,7 @@ static void attr_create_vertex_color(Scene *scene, Mesh *mesh, BL::Mesh &b_mesh,
         for (int i = 0; i < n; i++) {
           float4 color = get_float4(l->data[p->loop_start() + i].color());
           /* Compress/encode vertex color using the sRGB curve. */
-          *(cdata++) = color_float4_to_uchar4(color_srgb_to_linear_v4(color));
+          *(cdata++) = color_float4_to_uchar4(color);
         }
       }
     }
@@ -368,9 +368,10 @@ static void attr_create_vertex_color(Scene *scene, Mesh *mesh, BL::Mesh &b_mesh,
         float4 c3 = get_float4(l->data[li[2]].color());
 
         /* Compress/encode vertex color using the sRGB curve. */
-        cdata[0] = color_float4_to_uchar4(color_srgb_to_linear_v4(c1));
-        cdata[1] = color_float4_to_uchar4(color_srgb_to_linear_v4(c2));
-        cdata[2] = color_float4_to_uchar4(color_srgb_to_linear_v4(c3));
+        cdata[0] = color_float4_to_uchar4(c1);
+        cdata[1] = color_float4_to_uchar4(c2);
+        cdata[2] = color_float4_to_uchar4(c3);
+
         cdata += 3;
       }
     }