Cycles: Improved robustness of hair motion blur.motion_curve_fix

In some instances, the number of control vertices of a hair could change mid-frame.
Cycles would then be unable to calculate proper motion blur for those hairs. This adds
interpolated CVs to fill in for the missing data. While this will not necessarily result in
a fully accurate reconstruction of the guide hair, it preserves motion blur instead of disabling it.

Reviewers: #cycles, sergey

Reviewed By: #cycles, sergey

Subscribers: sergey, brecht, #cycles

Tags: #cycles

Differential Revision: https://developer.blender.org/D3695

1 files changed, 12 insertions, 2 deletions

diff --git a/intern/cycles/util/util_types_int4_impl.h b/intern/cycles/util/util_types_int4_impl.h
index 07cdc88f2dc..c058f86c400 100644
--- a/intern/cycles/util/util_types_int4_impl.h
+++ b/intern/cycles/util/util_types_int4_impl.h
@@ -43,12 +43,12 @@ __forceinline int4::int4(const __m128i& a)
 {
 }
 
-__forceinline int4::operator const __m128i&(void) const
+__forceinline int4::operator const __m128i&() const
 {
 	return m128;
 }
 
-__forceinline int4::operator __m128i&(void)
+__forceinline int4::operator __m128i&()
 {
 	return m128;
 }
@@ -104,6 +104,16 @@ ccl_device_inline int4 make_int4(const float3& f)
 	return a;
 }
 
+ccl_device_inline int4 make_int4(const float4& f)
+{
+#ifdef __KERNEL_SSE__
+	int4 a(_mm_cvtps_epi32(f.m128));
+#else
+	int4 a = {(int)f.x, (int)f.y, (int)f.z, (int)f.w};
+#endif
+	return a;
+}
+
 ccl_device_inline void print_int4(const char *label, const int4& a)
 {
 	printf("%s: %d %d %d %d\n", label, a.x, a.y, a.z, a.w);