Cycles: Enabled quaternion motion blur with Embree.

Bringing Embree's motion blur closer to Cycles' native blur.
This requries Embree 3.8.0 or newer.

Differential Revision: https://developer.blender.org/D6575

1 files changed, 13 insertions, 2 deletions

diff --git a/intern/cycles/bvh/bvh_embree.cpp b/intern/cycles/bvh/bvh_embree.cpp
index 851fdad7842..35c1b463b49 100644
--- a/intern/cycles/bvh/bvh_embree.cpp
+++ b/intern/cycles/bvh/bvh_embree.cpp
@@ -563,9 +563,20 @@ void BVHEmbree::add_instance(Object *ob, int i)
   rtcSetGeometryTimeStepCount(geom_id, num_motion_steps);
 
   if (ob->use_motion()) {
+    array<DecomposedTransform> decomp(ob->motion.size());
+    transform_motion_decompose(decomp.data(), ob->motion.data(), ob->motion.size());
     for (size_t step = 0; step < num_motion_steps; ++step) {
-      rtcSetGeometryTransform(
-          geom_id, step, RTC_FORMAT_FLOAT3X4_ROW_MAJOR, (const float *)&ob->motion[step]);
+      RTCQuaternionDecomposition rtc_decomp;
+      rtcInitQuaternionDecomposition(&rtc_decomp);
+      rtcQuaternionDecompositionSetQuaternion(
+          &rtc_decomp, decomp[step].x.w, decomp[step].x.x, decomp[step].x.y, decomp[step].x.z);
+      rtcQuaternionDecompositionSetScale(
+          &rtc_decomp, decomp[step].y.w, decomp[step].z.w, decomp[step].w.w);
+      rtcQuaternionDecompositionSetTranslation(
+          &rtc_decomp, decomp[step].y.x, decomp[step].y.y, decomp[step].y.z);
+      rtcQuaternionDecompositionSetSkew(
+          &rtc_decomp, decomp[step].z.x, decomp[step].z.y, decomp[step].w.x);
+      rtcSetGeometryTransformQuaternion(geom_id, step, &rtc_decomp);
     }
   }
   else {