Cycles: Implement camera zoom motion blur

Works totally similar to camera motion blur and majority of the changes are
related on just passing extra arguments to sync() functions.

Couple of things still to look into:

- Motion pass will not include motion caused by the zoom.
- Only perspective cameras are supported currently.
- Motion is being interpolated on projected coordinates, which might give
  different results from constructing projection matrix from interpolated
  field of view.

  This could be good enough for us, but we need to consider improving this
  at some point.

Reviewers: juicyfruit, dingto

Reviewed By: dingto

Differential Revision: https://developer.blender.org/D1383

1 files changed, 6 insertions, 2 deletions

diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 46e5d6b2a31..ba8cba1dc83 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -778,7 +778,7 @@ typedef struct KernelCamera {
 
 	/* motion blur */
 	float shuttertime;
-	int have_motion;
+	int have_motion, have_perspective_motion;
 
 	/* clipping */
 	float nearclip;
@@ -796,7 +796,6 @@ typedef struct KernelCamera {
 	float inv_aperture_ratio;
 
 	int is_inside_volume;
-	int pad2;
 
 	/* more matrices */
 	Transform screentoworld;
@@ -810,6 +809,11 @@ typedef struct KernelCamera {
 	Transform worldtocamera;
 
 	MotionTransform motion;
+
+	/* Denotes changes in the projective matrix, namely in rastertocamera.
+	 * Used for camera zoom motion blur,
+	 */
+	PerspectiveMotionTransform perspective_motion;
 } KernelCamera;
 
 typedef struct KernelFilm {