Hair Info Length Attribute

Goal is to add the length attribute to the Hair Info node, for better control over color gradients or similar along the hair.

Reviewed By: #eevee_viewport, brecht

Differential Revision: https://developer.blender.org/D10481

1 files changed, 18 insertions, 0 deletions

diff --git a/intern/cycles/blender/blender_curves.cpp b/intern/cycles/blender/blender_curves.cpp
index 6fe5ea41fff..c7851e40543 100644
--- a/intern/cycles/blender/blender_curves.cpp
+++ b/intern/cycles/blender/blender_curves.cpp
@@ -283,10 +283,13 @@ static void ExportCurveSegments(Scene *scene, Hair *hair, ParticleCurveData *CDa
     return;
 
   Attribute *attr_intercept = NULL;
+  Attribute *attr_length = NULL;
   Attribute *attr_random = NULL;
 
   if (hair->need_attribute(scene, ATTR_STD_CURVE_INTERCEPT))
     attr_intercept = hair->attributes.add(ATTR_STD_CURVE_INTERCEPT);
+  if (hair->need_attribute(scene, ATTR_STD_CURVE_LENGTH))
+    attr_length = hair->attributes.add(ATTR_STD_CURVE_LENGTH);
   if (hair->need_attribute(scene, ATTR_STD_CURVE_RANDOM))
     attr_random = hair->attributes.add(ATTR_STD_CURVE_RANDOM);
 
@@ -336,6 +339,11 @@ static void ExportCurveSegments(Scene *scene, Hair *hair, ParticleCurveData *CDa
         num_curve_keys++;
       }
 
+      if (attr_length != NULL)
+      {
+        attr_length->add(CData->curve_length[curve]);
+      }
+
       if (attr_random != NULL) {
         attr_random->add(hash_uint2_to_float(num_curves, 0));
       }
@@ -657,11 +665,16 @@ static void export_hair_curves(Scene *scene, Hair *hair, BL::Hair b_hair)
 
   /* Add requested attributes. */
   Attribute *attr_intercept = NULL;
+  Attribute *attr_length = NULL;
   Attribute *attr_random = NULL;
 
   if (hair->need_attribute(scene, ATTR_STD_CURVE_INTERCEPT)) {
     attr_intercept = hair->attributes.add(ATTR_STD_CURVE_INTERCEPT);
   }
+  if (hair->need_attribute(scene, ATTR_STD_CURVE_LENGTH))
+  {
+    attr_length = hair->attributes.add(ATTR_STD_CURVE_LENGTH);
+  }
   if (hair->need_attribute(scene, ATTR_STD_CURVE_RANDOM)) {
     attr_random = hair->attributes.add(ATTR_STD_CURVE_RANDOM);
   }
@@ -714,6 +727,11 @@ static void export_hair_curves(Scene *scene, Hair *hair, BL::Hair b_hair)
       }
     }
 
+  	if (attr_length) 
+    {
+      attr_length->add(length);
+    }
+
     /* Random number per curve. */
     if (attr_random != NULL) {
       attr_random->add(hash_uint2_to_float(b_curve.index(), 0));