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, 126 insertions, 0 deletions

diff --git a/intern/cycles/kernel/bvh/bvh_embree.h b/intern/cycles/kernel/bvh/bvh_embree.h
new file mode 100644
index 00000000000..34a099ebb4d
--- /dev/null
+++ b/intern/cycles/kernel/bvh/bvh_embree.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright 2018, Blender Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <embree3/rtcore_ray.h>
+#include <embree3/rtcore_scene.h>
+
+#include "kernel/kernel_compat_cpu.h"
+#include "kernel/split/kernel_split_data_types.h"
+#include "kernel/kernel_globals.h"
+#include "util/util_vector.h"
+
+CCL_NAMESPACE_BEGIN
+
+struct CCLIntersectContext  {
+	typedef enum {
+		RAY_REGULAR = 0,
+		RAY_SHADOW_ALL = 1,
+		RAY_SSS = 2,
+		RAY_VOLUME_ALL = 3,
+		
+	} RayType;
+
+	KernelGlobals *kg;
+	RayType type;
+
+	/* for shadow rays */
+	Intersection *isect_s;
+	int max_hits;
+	int num_hits;
+
+	/* for SSS Rays: */
+	LocalIntersection *ss_isect;
+	int sss_object_id;
+	uint *lcg_state;
+
+	CCLIntersectContext(KernelGlobals *kg_,  RayType type_)
+	{
+		kg = kg_;
+		type = type_;
+		max_hits = 1;
+		num_hits = 0;
+		isect_s = NULL;
+		ss_isect = NULL;
+		sss_object_id = -1;
+		lcg_state = NULL;
+	}
+};
+
+class IntersectContext
+{
+public:
+	IntersectContext(CCLIntersectContext* ctx)
+	{
+		rtcInitIntersectContext(&context);
+		userRayExt = ctx;
+	}
+	RTCIntersectContext context;
+	CCLIntersectContext* userRayExt;
+};
+
+ccl_device_inline void kernel_embree_setup_ray(const Ray& ray, RTCRay& rtc_ray, const uint visibility)
+{
+	rtc_ray.org_x = ray.P.x;
+	rtc_ray.org_y = ray.P.y;
+	rtc_ray.org_z = ray.P.z;
+	rtc_ray.dir_x = ray.D.x;
+	rtc_ray.dir_y = ray.D.y;
+	rtc_ray.dir_z = ray.D.z;
+	rtc_ray.tnear = 0.0f;
+	rtc_ray.tfar = ray.t;
+	rtc_ray.time = ray.time;
+	rtc_ray.mask = visibility;
+}
+
+ccl_device_inline void kernel_embree_setup_rayhit(const Ray& ray, RTCRayHit& rayhit, const uint visibility)
+{
+	kernel_embree_setup_ray(ray, rayhit.ray, visibility);
+	rayhit.hit.geomID = RTC_INVALID_GEOMETRY_ID;
+	rayhit.hit.primID = RTC_INVALID_GEOMETRY_ID;
+}
+
+ccl_device_inline void kernel_embree_convert_hit(KernelGlobals *kg, const RTCRay *ray, const RTCHit *hit, Intersection *isect)
+{
+	bool is_hair = hit->geomID & 1;
+	isect->u = is_hair ? hit->u : 1.0f - hit->v - hit->u;
+	isect->v = is_hair ? hit->v : hit->u;
+	isect->t = ray->tfar;
+	isect->Ng = make_float3(hit->Ng_x, hit->Ng_y, hit->Ng_z);
+	if(hit->instID[0] != RTC_INVALID_GEOMETRY_ID) {
+		RTCScene inst_scene = (RTCScene)rtcGetGeometryUserData(rtcGetGeometry(kernel_data.bvh.scene, hit->instID[0]));
+		isect->prim = hit->primID + (intptr_t)rtcGetGeometryUserData(rtcGetGeometry(inst_scene, hit->geomID)) + kernel_tex_fetch(__object_node, hit->instID[0]/2);
+		isect->object = hit->instID[0]/2;
+	}
+	else {
+		isect->prim = hit->primID + (intptr_t)rtcGetGeometryUserData(rtcGetGeometry(kernel_data.bvh.scene, hit->geomID));
+		isect->object = OBJECT_NONE;
+	}
+	isect->type = kernel_tex_fetch(__prim_type, isect->prim);
+}
+
+ccl_device_inline void kernel_embree_convert_local_hit(KernelGlobals *kg, const RTCRay *ray, const RTCHit *hit, Intersection *isect, int local_object_id)
+{
+	isect->u = 1.0f - hit->v - hit->u;
+	isect->v = hit->u;
+	isect->t = ray->tfar;
+	isect->Ng = make_float3(hit->Ng_x, hit->Ng_y, hit->Ng_z);
+	RTCScene inst_scene = (RTCScene)rtcGetGeometryUserData(rtcGetGeometry(kernel_data.bvh.scene, local_object_id * 2));
+	isect->prim = hit->primID + (intptr_t)rtcGetGeometryUserData(rtcGetGeometry(inst_scene, hit->geomID)) + kernel_tex_fetch(__object_node, local_object_id);
+	isect->object = local_object_id;
+	isect->type = kernel_tex_fetch(__prim_type, isect->prim);
+}
+
+CCL_NAMESPACE_END