Cycles: support arbitrary number of motion blur steps for cameras.

18 files changed, 174 insertions, 131 deletions

diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index e3076a8ec2c..707f8756f6f 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -809,7 +809,7 @@ class CYCLES_OBJECT_PT_motion_blur(CyclesButtonsPanel, Panel):
     def poll(cls, context):
         ob = context.object
         if CyclesButtonsPanel.poll(context) and ob:
-            if ob.type in {'MESH', 'CURVE', 'CURVE', 'SURFACE', 'FONT', 'META'}:
+            if ob.type in {'MESH', 'CURVE', 'CURVE', 'SURFACE', 'FONT', 'META', 'CAMERA'}:
                 return True
             if ob.dupli_type == 'GROUP' and ob.dupli_group:
                 return True
@@ -841,11 +841,9 @@ class CYCLES_OBJECT_PT_motion_blur(CyclesButtonsPanel, Panel):
         layout.active = (rd.use_motion_blur and cob.use_motion_blur)
 
         row = layout.row()
-        row.prop(cob, "use_deform_motion", text="Deformation")
-
-        sub = row.row()
-        sub.active = cob.use_deform_motion
-        sub.prop(cob, "motion_steps", text="Steps")
+        if ob.type != 'CAMERA':
+            row.prop(cob, "use_deform_motion", text="Deformation")
+        row.prop(cob, "motion_steps", text="Steps")
 
 
 class CYCLES_OBJECT_PT_cycles_settings(CyclesButtonsPanel, Panel):
diff --git a/intern/cycles/blender/blender_camera.cpp b/intern/cycles/blender/blender_camera.cpp
index e5f885c0012..909db8d9449 100644
--- a/intern/cycles/blender/blender_camera.cpp
+++ b/intern/cycles/blender/blender_camera.cpp
@@ -83,6 +83,8 @@ struct BlenderCamera {
 	Transform matrix;
 
 	float offscreen_dicing_scale;
+
+	int motion_steps;
 };
 
 static void blender_camera_init(BlenderCamera *bcam,
@@ -226,6 +228,10 @@ static void blender_camera_from_object(BlenderCamera *bcam,
 			bcam->sensor_fit = BlenderCamera::HORIZONTAL;
 		else
 			bcam->sensor_fit = BlenderCamera::VERTICAL;
+
+		if(object_use_motion(b_ob, b_ob)) {
+			bcam->motion_steps = object_motion_steps(b_ob);
+		}
 	}
 	else {
 		/* from lamp not implemented yet */
@@ -453,9 +459,7 @@ static void blender_camera_sync(Camera *cam,
 	cam->matrix = blender_camera_matrix(bcam->matrix,
 	                                    bcam->type,
 	                                    bcam->panorama_type);
-	cam->motion.pre = cam->matrix;
-	cam->motion.post = cam->matrix;
-	cam->use_motion = false;
+	cam->motion.resize(bcam->motion_steps, cam->matrix);
 	cam->use_perspective_motion = false;
 	cam->shuttertime = bcam->shuttertime;
 	cam->fov_pre = cam->fov;
@@ -564,20 +568,15 @@ void BlenderSync::sync_camera_motion(BL::RenderSettings& b_render,
 	Transform tfm = get_transform(b_ob_matrix);
 	tfm = blender_camera_matrix(tfm, cam->type, cam->panorama_type);
 
-	if(tfm != cam->matrix) {
-		VLOG(1) << "Camera " << b_ob.name() << " motion detected.";
-		if(motion_time == 0.0f) {
-			/* When motion blur is not centered in frame, cam->matrix gets reset. */
-			cam->matrix = tfm;
-		}
-		else if(motion_time == -1.0f) {
-			cam->motion.pre = tfm;
-			cam->use_motion = true;
-		}
-		else if(motion_time == 1.0f) {
-			cam->motion.post = tfm;
-			cam->use_motion = true;
-		}
+	if(motion_time == 0.0f) {
+		/* When motion blur is not centered in frame, cam->matrix gets reset. */
+		cam->matrix = tfm;
+	}
+
+	/* Set transform in motion array. */
+	int motion_step = cam->motion_step(motion_time);
+	if(motion_step >= 0) {
+		cam->motion[motion_step] = tfm;
 	}
 
 	if(cam->type == CAMERA_PERSPECTIVE) {
diff --git a/intern/cycles/kernel/geom/geom_object.h b/intern/cycles/kernel/geom/geom_object.h
index a7191c50e97..67d039e1bc7 100644
--- a/intern/cycles/kernel/geom/geom_object.h
+++ b/intern/cycles/kernel/geom/geom_object.h
@@ -82,7 +82,7 @@ ccl_device_inline Transform object_fetch_transform_motion(KernelGlobals *kg, int
 	const ccl_global DecomposedMotionTransform *motion = &kernel_tex_fetch(__objects, object).tfm;
 
 	Transform tfm;
-	transform_motion_interpolate(&tfm, motion, time);
+	transform_motion_array_interpolate(&tfm, &motion->pre, 3, time);
 
 	return tfm;
 }
diff --git a/intern/cycles/kernel/kernel_camera.h b/intern/cycles/kernel/kernel_camera.h
index a0be0ba6454..b73ad47dad3 100644
--- a/intern/cycles/kernel/kernel_camera.h
+++ b/intern/cycles/kernel/kernel_camera.h
@@ -91,11 +91,12 @@ ccl_device void camera_sample_perspective(KernelGlobals *kg, float raster_x, flo
 	Transform cameratoworld = kernel_data.cam.cameratoworld;
 
 #ifdef __CAMERA_MOTION__
-	if(kernel_data.cam.have_motion) {
-		ccl_constant DecomposedMotionTransform *motion = &kernel_data.cam.motion;
-		transform_motion_interpolate_constant(&cameratoworld,
-		                                      motion,
-		                                      ray->time);
+	if(kernel_data.cam.num_motion_steps) {
+		transform_motion_array_interpolate(
+			&cameratoworld,
+			kernel_tex_array(__camera_motion),
+			kernel_data.cam.num_motion_steps,
+			ray->time);
 	}
 #endif
 
@@ -197,11 +198,12 @@ ccl_device void camera_sample_orthographic(KernelGlobals *kg, float raster_x, fl
 	Transform cameratoworld = kernel_data.cam.cameratoworld;
 
 #ifdef __CAMERA_MOTION__
-	if(kernel_data.cam.have_motion) {
-		ccl_constant DecomposedMotionTransform *motion = &kernel_data.cam.motion;
-		transform_motion_interpolate_constant(&cameratoworld,
-		                                      motion,
-		                                      ray->time);
+	if(kernel_data.cam.num_motion_steps) {
+		transform_motion_array_interpolate(
+			&cameratoworld,
+			kernel_tex_array(__camera_motion),
+			kernel_data.cam.num_motion_steps,
+			ray->time);
 	}
 #endif
 
@@ -227,6 +229,7 @@ ccl_device void camera_sample_orthographic(KernelGlobals *kg, float raster_x, fl
 /* Panorama Camera */
 
 ccl_device_inline void camera_sample_panorama(ccl_constant KernelCamera *cam,
+                                              const ccl_global DecomposedTransform *cam_motion,
                                               float raster_x, float raster_y,
                                               float lens_u, float lens_v,
                                               ccl_addr_space Ray *ray)
@@ -269,11 +272,12 @@ ccl_device_inline void camera_sample_panorama(ccl_constant KernelCamera *cam,
 	Transform cameratoworld = cam->cameratoworld;
 
 #ifdef __CAMERA_MOTION__
-	if(cam->have_motion) {
-		ccl_constant DecomposedMotionTransform *motion = &cam->motion;
-		transform_motion_interpolate_constant(&cameratoworld,
-		                                      motion,
-		                                      ray->time);
+	if(cam->num_motion_steps) {
+		transform_motion_array_interpolate(
+			&cameratoworld,
+			cam_motion,
+			cam->num_motion_steps,
+			ray->time);
 	}
 #endif
 
@@ -392,12 +396,16 @@ ccl_device_inline void camera_sample(KernelGlobals *kg,
 #endif
 
 	/* sample */
-	if(kernel_data.cam.type == CAMERA_PERSPECTIVE)
+	if(kernel_data.cam.type == CAMERA_PERSPECTIVE) {
 		camera_sample_perspective(kg, raster_x, raster_y, lens_u, lens_v, ray);
-	else if(kernel_data.cam.type == CAMERA_ORTHOGRAPHIC)
+	}
+	else if(kernel_data.cam.type == CAMERA_ORTHOGRAPHIC) {
 		camera_sample_orthographic(kg, raster_x, raster_y, lens_u, lens_v, ray);
-	else
-		camera_sample_panorama(&kernel_data.cam, raster_x, raster_y, lens_u, lens_v, ray);
+	}
+	else {
+		const ccl_global DecomposedTransform *cam_motion = kernel_tex_array(__camera_motion);
+		camera_sample_panorama(&kernel_data.cam, cam_motion, raster_x, raster_y, lens_u, lens_v, ray);
+	}
 }
 
 /* Utilities */
diff --git a/intern/cycles/kernel/kernel_compat_cpu.h b/intern/cycles/kernel/kernel_compat_cpu.h
index 61cd90e9d2a..d26b668cb11 100644
--- a/intern/cycles/kernel/kernel_compat_cpu.h
+++ b/intern/cycles/kernel/kernel_compat_cpu.h
@@ -118,6 +118,7 @@ template<typename T> struct texture  {
 #define kernel_tex_fetch_ssef(tex, index) (kg->tex.fetch_ssef(index))
 #define kernel_tex_fetch_ssei(tex, index) (kg->tex.fetch_ssei(index))
 #define kernel_tex_lookup(tex, t, offset, size) (kg->tex.lookup(t, offset, size))
+#define kernel_tex_array(tex) (kg->tex.data)
 
 #define kernel_data (kg->__data)
 
diff --git a/intern/cycles/kernel/kernel_compat_cuda.h b/intern/cycles/kernel/kernel_compat_cuda.h
index 9bd7a572f5f..ac63bcf7ac9 100644
--- a/intern/cycles/kernel/kernel_compat_cuda.h
+++ b/intern/cycles/kernel/kernel_compat_cuda.h
@@ -137,6 +137,7 @@ ccl_device_inline uint ccl_num_groups(uint d)
 
 /* Use arrays for regular data. */
 #define kernel_tex_fetch(t, index) t[(index)]
+#define kernel_tex_array(t) (t)
 
 #define kernel_data __data
 
diff --git a/intern/cycles/kernel/kernel_compat_opencl.h b/intern/cycles/kernel/kernel_compat_opencl.h
index b02e3bc576d..671c47e2225 100644
--- a/intern/cycles/kernel/kernel_compat_opencl.h
+++ b/intern/cycles/kernel/kernel_compat_opencl.h
@@ -144,7 +144,8 @@
 
 /* data lookup defines */
 #define kernel_data (*kg->data)
-#define kernel_tex_fetch(tex, index) ((const ccl_global tex##_t*)(kg->buffers[kg->tex.cl_buffer] + kg->tex.data))[(index)]
+#define kernel_tex_array(tex) ((const ccl_global tex##_t*)(kg->buffers[kg->tex.cl_buffer] + kg->tex.data))
+#define kernel_tex_fetch(tex, index) kernel_tex_array(tex)[(index)]
 
 /* define NULL */
 #define NULL 0
diff --git a/intern/cycles/kernel/kernel_textures.h b/intern/cycles/kernel/kernel_textures.h
index 564b3f0f79c..56de5b27605 100644
--- a/intern/cycles/kernel/kernel_textures.h
+++ b/intern/cycles/kernel/kernel_textures.h
@@ -35,6 +35,9 @@ KERNEL_TEX(KernelObject, __objects)
 KERNEL_TEX(Transform, __object_motion_pass)
 KERNEL_TEX(uint, __object_flag)
 
+/* cameras */
+KERNEL_TEX(DecomposedTransform, __camera_motion)
+
 /* triangles */
 KERNEL_TEX(uint, __tri_shader)
 KERNEL_TEX(float4, __tri_vnormal)
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 6743cc62894..2c3b7ba29a4 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -1173,7 +1173,7 @@ typedef struct KernelCamera {
 
 	/* motion blur */
 	float shuttertime;
-	int have_motion, have_perspective_motion;
+	int num_motion_steps, have_perspective_motion;
 
 	/* clipping */
 	float nearclip;
@@ -1201,8 +1201,6 @@ typedef struct KernelCamera {
 	ProjectionTransform worldtondc;
 	Transform worldtocamera;
 
-	DecomposedMotionTransform motion;
-
 	/* Stores changes in the projeciton matrix. Use for camera zoom motion
 	 * blur and motion pass output for perspective camera. */
 	ProjectionTransform perspective_pre;
diff --git a/intern/cycles/render/camera.cpp b/intern/cycles/render/camera.cpp
index a1c6a279956..38936ffc094 100644
--- a/intern/cycles/render/camera.cpp
+++ b/intern/cycles/render/camera.cpp
@@ -82,6 +82,7 @@ NODE_DEFINE(Camera)
 	SOCKET_FLOAT(bladesrotation, "Blades Rotation", 0.0f);
 
 	SOCKET_TRANSFORM(matrix, "Matrix", transform_identity());
+	SOCKET_TRANSFORM_ARRAY(motion, "Motion", array<Transform>());
 
 	SOCKET_FLOAT(aperture_ratio, "Aperture Ratio", 1.0f);
 
@@ -151,9 +152,6 @@ Camera::Camera()
 	height = 512;
 	resolution = 1;
 
-	motion.pre = transform_identity();
-	motion.post = transform_identity();
-	use_motion = false;
 	use_perspective_motion = false;
 
 	shutter_curve.resize(RAMP_TABLE_SIZE);
@@ -317,15 +315,22 @@ void Camera::update(Scene *scene)
 	kcam->ndctoworld = ndctoworld;
 
 	/* camera motion */
-	kcam->have_motion = 0;
+	kcam->num_motion_steps = 0;
 	kcam->have_perspective_motion = 0;
+	kernel_camera_motion.clear();
+
+	/* Test if any of the transforms are actually different. */
+	bool have_motion = false;
+	for(size_t i = 0; i < motion.size(); i++) {
+		have_motion = have_motion || motion[i] != matrix;
+	}
 
 	if(need_motion == Scene::MOTION_PASS) {
 		/* TODO(sergey): Support perspective (zoom, fov) motion. */
 		if(type == CAMERA_PANORAMA) {
-			if(use_motion) {
-				kcam->motion_pass_pre = transform_inverse(motion.pre);
-				kcam->motion_pass_post = transform_inverse(motion.post);
+			if(have_motion) {
+				kcam->motion_pass_pre = transform_inverse(motion[0]);
+				kcam->motion_pass_post = transform_inverse(motion[motion.size()-1]);
 			}
 			else {
 				kcam->motion_pass_pre = kcam->worldtocamera;
@@ -333,9 +338,9 @@ void Camera::update(Scene *scene)
 			}
 		}
 		else {
-			if(use_motion) {
-				kcam->perspective_pre = cameratoraster * transform_inverse(motion.pre);
-				kcam->perspective_post = cameratoraster * transform_inverse(motion.post);
+			if(have_motion) {
+				kcam->perspective_pre = cameratoraster * transform_inverse(motion[0]);
+				kcam->perspective_post = cameratoraster * transform_inverse(motion[motion.size()-1]);
 			}
 			else {
 				kcam->perspective_pre = worldtoraster;
@@ -344,9 +349,10 @@ void Camera::update(Scene *scene)
 		}
 	}
 	else if(need_motion == Scene::MOTION_BLUR) {
-		if(use_motion) {
-			transform_motion_decompose(&kcam->motion, &motion, &matrix);
-			kcam->have_motion = 1;
+		if(have_motion) {
+			kernel_camera_motion.resize(motion.size());
+			transform_motion_decompose(kernel_camera_motion.data(), motion.data(), motion.size());
+			kcam->num_motion_steps = motion.size();
 		}
 
 		/* TODO(sergey): Support other types of camera. */
@@ -469,6 +475,16 @@ void Camera::device_update(Device * /* device */,
 	}
 
 	dscene->data.cam = kernel_camera;
+
+	size_t num_motion_steps = kernel_camera_motion.size();
+	if(num_motion_steps) {
+		DecomposedTransform *camera_motion = dscene->camera_motion.alloc(num_motion_steps);
+		memcpy(camera_motion, kernel_camera_motion.data(), sizeof(*camera_motion) * num_motion_steps);
+		dscene->camera_motion.copy_to_device();
+	}
+	else {
+		dscene->camera_motion.free();
+	}
 }
 
 void Camera::device_update_volume(Device * /*device*/,
@@ -495,10 +511,11 @@ void Camera::device_update_volume(Device * /*device*/,
 }
 
 void Camera::device_free(Device * /*device*/,
-                         DeviceScene * /*dscene*/,
+                         DeviceScene *dscene,
                          Scene *scene)
 {
 	scene->lookup_tables->remove_table(&shutter_table_offset);
+	dscene->camera_motion.free();
 }
 
 bool Camera::modified(const Camera& cam)
@@ -509,7 +526,6 @@ bool Camera::modified(const Camera& cam)
 bool Camera::motion_modified(const Camera& cam)
 {
 	return !((motion == cam.motion) &&
-	         (use_motion == cam.use_motion) &&
 	         (use_perspective_motion == cam.use_perspective_motion));
 }
 
@@ -706,17 +722,17 @@ float Camera::world_to_raster_size(float3 P)
 		 * may be a better way to do this, but calculating differentials from the
 		 * point directly ahead seems to produce good enough results. */
 #if 0
-		float2 dir = direction_to_panorama(&kernel_camera, normalize(D));
+		float2 dir = direction_to_panorama(&kernel_camera, kernel_camera_motion.data(), normalize(D));
 		float3 raster = transform_perspective(&cameratoraster, make_float3(dir.x, dir.y, 0.0f));
 
 		ray.t = 1.0f;
-		camera_sample_panorama(&kernel_camera, raster.x, raster.y, 0.0f, 0.0f, &ray);
+		camera_sample_panorama(&kernel_camera, kernel_camera_motion.data(), raster.x, raster.y, 0.0f, 0.0f, &ray);
 		if(ray.t == 0.0f) {
 			/* No differentials, just use from directly ahead. */
-			camera_sample_panorama(&kernel_camera, 0.5f*width, 0.5f*height, 0.0f, 0.0f, &ray);
+			camera_sample_panorama(&kernel_camera, kernel_camera_motion.data(), 0.5f*width, 0.5f*height, 0.0f, 0.0f, &ray);
 		}
 #else
-		camera_sample_panorama(&kernel_camera, 0.5f*width, 0.5f*height, 0.0f, 0.0f, &ray);
+		camera_sample_panorama(&kernel_camera, kernel_camera_motion.data(), 0.5f*width, 0.5f*height, 0.0f, 0.0f, &ray);
 #endif
 
 		differential_transfer(&ray.dP, ray.dP, ray.D, ray.dD, ray.D, dist);
@@ -728,4 +744,27 @@ float Camera::world_to_raster_size(float3 P)
 	return res;
 }
 
+bool Camera::use_motion() const
+{
+	return motion.size() > 1;
+}
+
+float Camera::motion_time(int step) const
+{
+	return (use_motion()) ? 2.0f * step / (motion.size() - 1) - 1.0f : 0.0f;
+}
+
+int Camera::motion_step(float time) const
+{
+	if(use_motion()) {
+		for(int step = 0; step < motion.size(); step++) {
+			if(time == motion_time(step)) {
+				return step;
+			}
+		}
+	}
+
+	return -1;
+}
+
 CCL_NAMESPACE_END
diff --git a/intern/cycles/render/camera.h b/intern/cycles/render/camera.h
index 8f49a372f24..37d05c01bd9 100644
--- a/intern/cycles/render/camera.h
+++ b/intern/cycles/render/camera.h
@@ -141,8 +141,8 @@ public:
 	Transform matrix;
 
 	/* motion */
-	MotionTransform motion;
-	bool use_motion, use_perspective_motion;
+	array<Transform> motion;
+	bool use_perspective_motion;
 	float fov_pre, fov_post;
 
 	/* computed camera parameters */
@@ -176,6 +176,7 @@ public:
 
 	/* Kernel camera data, copied here for dicing. */
 	KernelCamera kernel_camera;
+	array<DecomposedTransform> kernel_camera_motion;
 
 	/* functions */
 	Camera();
@@ -199,6 +200,11 @@ public:
 	/* Calculates the width of a pixel at point in world space. */
 	float world_to_raster_size(float3 P);
 
+	/* Motion blur. */
+	float motion_time(int step) const;
+	int motion_step(float time) const;
+	bool use_motion() const;
+
 private:
 	/* Private utility functions. */
 	float3 transform_raster_to_world(float raster_x, float raster_y);
diff --git a/intern/cycles/render/object.cpp b/intern/cycles/render/object.cpp
index 6201775b992..bde340ae928 100644
--- a/intern/cycles/render/object.cpp
+++ b/intern/cycles/render/object.cpp
@@ -139,9 +139,10 @@ void Object::compute_bounds(bool motion_blur)
 		if(mtfm.post == transform_empty()) {
 			mtfm.post = tfm;
 		}
+		mtfm.mid = tfm;
 
 		DecomposedMotionTransform decomp;
-		transform_motion_decompose(&decomp, &mtfm, &tfm);
+		transform_motion_decompose(&decomp.pre, &mtfm.pre, 3);
 
 		bounds = BoundBox::empty;
 
@@ -151,7 +152,7 @@ void Object::compute_bounds(bool motion_blur)
 		for(float t = 0.0f; t < 1.0f; t += (1.0f/128.0f)) {
 			Transform ttfm;
 
-			transform_motion_interpolate(&ttfm, &decomp, t);
+			transform_motion_array_interpolate(&ttfm, &decomp.pre, 3, t);
 			bounds.grow(mbounds.transformed(&ttfm));
 		}
 	}
@@ -422,8 +423,10 @@ void ObjectManager::device_update_object_transform(UpdateObjectTransformState *s
 		if(ob->use_motion) {
 			/* decompose transformations for interpolation. */
 			DecomposedMotionTransform decomp;
+			MotionTransform mtfm = ob->motion;
+			mtfm.mid = tfm;
 
-			transform_motion_decompose(&decomp, &ob->motion, &ob->tfm);
+			transform_motion_decompose(&decomp.pre, &mtfm.pre, 3);
 			kobject.tfm = decomp;
 			flag |= SD_OBJECT_MOTION;
 			state->have_motion = true;
diff --git a/intern/cycles/render/scene.cpp b/intern/cycles/render/scene.cpp
index e9b9b417e30..6fc6e453aff 100644
--- a/intern/cycles/render/scene.cpp
+++ b/intern/cycles/render/scene.cpp
@@ -62,6 +62,7 @@ DeviceScene::DeviceScene(Device *device)
   objects(device, "__objects", MEM_TEXTURE),
   object_motion_pass(device, "__object_motion_pass", MEM_TEXTURE),
   object_flag(device, "__object_flag", MEM_TEXTURE),
+  camera_motion(device, "__camera_motion", MEM_TEXTURE),
   attributes_map(device, "__attributes_map", MEM_TEXTURE),
   attributes_float(device, "__attributes_float", MEM_TEXTURE),
   attributes_float3(device, "__attributes_float3", MEM_TEXTURE),
diff --git a/intern/cycles/render/scene.h b/intern/cycles/render/scene.h
index aebd84f92d8..74e1df2f1d2 100644
--- a/intern/cycles/render/scene.h
+++ b/intern/cycles/render/scene.h
@@ -90,6 +90,9 @@ public:
 	device_vector<Transform> object_motion_pass;
 	device_vector<uint> object_flag;
 
+	/* cameras */
+	device_vector<DecomposedTransform> camera_motion;
+
 	/* attributes */
 	device_vector<uint4> attributes_map;
 	device_vector<float> attributes_float;
diff --git a/intern/cycles/render/session.cpp b/intern/cycles/render/session.cpp
index e8d9558c38d..5732faf2a36 100644
--- a/intern/cycles/render/session.cpp
+++ b/intern/cycles/render/session.cpp
@@ -656,7 +656,7 @@ DeviceRequestedFeatures Session::get_requested_device_features()
 	 */
 	requested_features.use_hair = false;
 	requested_features.use_object_motion = false;
-	requested_features.use_camera_motion = scene->camera->use_motion;
+	requested_features.use_camera_motion = scene->camera->use_motion();
 	foreach(Object *object, scene->objects) {
 		Mesh *mesh = object->mesh;
 		if(mesh->num_curves()) {
diff --git a/intern/cycles/util/util_transform.cpp b/intern/cycles/util/util_transform.cpp
index e4e0d627497..206c3da23eb 100644
--- a/intern/cycles/util/util_transform.cpp
+++ b/intern/cycles/util/util_transform.cpp
@@ -261,18 +261,18 @@ static void transform_decompose(DecomposedTransform *decomp, const Transform *tf
 	decomp->w = make_float4(scale.y.z, scale.z.x, scale.z.y, scale.z.z);
 }
 
-void transform_motion_decompose(DecomposedMotionTransform *decomp, const MotionTransform *motion, const Transform *mid)
+void transform_motion_decompose(DecomposedTransform *decomp, const Transform *motion, size_t size)
 {
-	transform_decompose(&decomp->pre, &motion->pre);
-	transform_decompose(&decomp->mid, mid);
-	transform_decompose(&decomp->post, &motion->post);
-
-	/* ensure rotation around shortest angle, negated quaternions are the same
-	 * but this means we don't have to do the check in quat_interpolate */
-	if(dot(decomp->pre.x, decomp->mid.x) < 0.0f)
-		decomp->pre.x = -decomp->pre.x;
-	if(dot(decomp->mid.x, decomp->post.x) < 0.0f)
-		decomp->mid.x = -decomp->mid.x;
+	for(size_t i = 0; i < size; i++) {
+		transform_decompose(decomp + i, motion + i);
+
+		if(i > 0) {
+			/* Ensure rotation around shortest angle, negated quaternions are the same
+			 * but this means we don't have to do the check in quat_interpolate */
+			if(dot(decomp[i-1].x, decomp[i].x) < 0.0f)
+				decomp[i-1].x = -decomp[i-1].x;
+		}
+	}
 }
 
 Transform transform_from_viewplane(BoundBox2D& viewplane)
diff --git a/intern/cycles/util/util_transform.h b/intern/cycles/util/util_transform.h
index 12f8405f233..ade74364876 100644
--- a/intern/cycles/util/util_transform.h
+++ b/intern/cycles/util/util_transform.h
@@ -409,58 +409,28 @@ ccl_device_inline void transform_compose(Transform *tfm, const DecomposedTransfo
 	tfm->z = make_float4(dot(rotation_z, scale_x), dot(rotation_z, scale_y), dot(rotation_z, scale_z), decomp->y.z);
 }
 
-ccl_device void transform_motion_interpolate(Transform *tfm, const ccl_global DecomposedMotionTransform *motion, float t)
+/* Interpolate from array of decomposed transforms. */
+ccl_device void transform_motion_array_interpolate(Transform *tfm,
+                                                   const ccl_global DecomposedTransform *motion,
+                                                   uint numsteps,
+                                                   float time)
 {
-	DecomposedTransform decomp;
-
-	/* linear interpolation for rotation and scale */
-	if(t < 0.5f) {
-		t *= 2.0f;
-
-		decomp.x = quat_interpolate(motion->pre.x, motion->mid.x, t);
-		decomp.y = (1.0f - t)*motion->pre.y + t*motion->mid.y;
-		decomp.z = (1.0f - t)*motion->pre.z + t*motion->mid.z;
-		decomp.w = (1.0f - t)*motion->pre.w + t*motion->mid.w;
-	}
-	else {
-		t = (t - 0.5f)*2.0f;
+	/* Figure out which steps we need to interpolate. */
+	int maxstep = numsteps-1;
+	int step = min((int)(time*maxstep), maxstep-1);
+	float t = time*maxstep - step;
 
-		decomp.x = quat_interpolate(motion->mid.x, motion->post.x, t);
-		decomp.y = (1.0f - t)*motion->mid.y + t*motion->post.y;
-		decomp.z = (1.0f - t)*motion->mid.z + t*motion->post.z;
-		decomp.w = (1.0f - t)*motion->mid.w + t*motion->post.w;
-	}
-
-	/* compose rotation, translation, scale into matrix */
-	transform_compose(tfm, &decomp);
-}
+	const ccl_global DecomposedTransform *a = motion + step;
+	const ccl_global DecomposedTransform *b = motion + step + 1;
 
-ccl_device void transform_motion_interpolate_constant(Transform *tfm, ccl_constant DecomposedMotionTransform *motion, float t)
-{
-	/* possible optimization: is it worth it adding a check to skip scaling?
-	 * it's probably quite uncommon to have scaling objects. or can we skip
-	 * just shearing perhaps? */
+	/* Interpolate rotation, translation and scale. */
 	DecomposedTransform decomp;
+	decomp.x = quat_interpolate(a->x, b->x, t);
+	decomp.y = (1.0f - t)*a->y + t*b->y;
+	decomp.z = (1.0f - t)*a->z + t*b->z;
+	decomp.w = (1.0f - t)*a->w + t*b->w;
 
-	/* linear interpolation for rotation and scale */
-	if(t < 0.5f) {
-		t *= 2.0f;
-
-		decomp.x = quat_interpolate(motion->pre.x, motion->mid.x, t);
-		decomp.y = (1.0f - t)*motion->pre.y + t*motion->mid.y;
-		decomp.z = (1.0f - t)*motion->pre.z + t*motion->mid.z;
-		decomp.w = (1.0f - t)*motion->pre.w + t*motion->mid.w;
-	}
-	else {
-		t = (t - 0.5f)*2.0f;
-
-		decomp.x = quat_interpolate(motion->mid.x, motion->post.x, t);
-		decomp.y = (1.0f - t)*motion->mid.y + t*motion->post.y;
-		decomp.z = (1.0f - t)*motion->mid.z + t*motion->post.z;
-		decomp.w = (1.0f - t)*motion->mid.w + t*motion->post.w;
-	}
-
-	/* compose rotation, translation, scale into matrix */
+	/* Compose rotation, translation, scale into matrix. */
 	transform_compose(tfm, &decomp);
 }
 
@@ -479,7 +449,7 @@ ccl_device_inline bool operator==(const MotionTransform& A, const MotionTransfor
 }
 
 float4 transform_to_quat(const Transform& tfm);
-void transform_motion_decompose(DecomposedMotionTransform *decomp, const MotionTransform *motion, const Transform *mid);
+void transform_motion_decompose(DecomposedTransform *decomp, const Transform *motion, size_t size);
 Transform transform_from_viewplane(BoundBox2D& viewplane);
 
 #endif
diff --git a/intern/cycles/util/util_vector.h b/intern/cycles/util/util_vector.h
index 625c19c7c46..e98e4e34181 100644
--- a/intern/cycles/util/util_vector.h
+++ b/intern/cycles/util/util_vector.h
@@ -215,6 +215,18 @@ public:
 		return data_;
 	}
 
+	T* resize(size_t newsize, const T& value)
+	{
+		size_t oldsize = size();
+		resize(newsize);
+
+		for(size_t i = oldsize; i < size(); i++) {
+			data_[i] = value;
+		}
+
+		return data_;
+	}
+
 	void clear()
 	{
 		if(data_ != NULL) {