Cycles: Pole merging for spherical stereo

The idea of pole merge is to fade interocular distance after a certain
altitude to zero when altitude goes closer to a pole. This should prevent
annoyances looking up in the sky or down to the bottom.

Works for both panorama and perspective cameras when Spherical Stereo
is enabled.

Reviewers: dfelinto, brecht

Reviewed By: brecht

Subscribers: sebastian_k

Differential Revision: https://developer.blender.org/D1998

4 files changed, 36 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/camera.c b/source/blender/blenkernel/intern/camera.c
index bdf3432e6ea..96bac2c2f41 100644
--- a/source/blender/blenkernel/intern/camera.c
+++ b/source/blender/blenkernel/intern/camera.c
@@ -76,6 +76,8 @@ void BKE_camera_init(Camera *cam)
 	/* stereoscopy 3d */
 	cam->stereo.interocular_distance = 0.065f;
 	cam->stereo.convergence_distance = 30.f * 0.065f;
+	cam->stereo.pole_merge_angle_from = DEG2RAD(60.0f);
+	cam->stereo.pole_merge_angle_to = DEG2RAD(75.0f);
 }
 
 void *BKE_camera_add(Main *bmain, const char *name)
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index 58542d05879..0ea4078a5cb 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -1190,4 +1190,15 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *main)
 			}
 		}
 	}
+
+	{
+		for (Camera *camera = main->camera.first; camera != NULL; camera = camera->id.next) {
+			if (camera->stereo.pole_merge_angle_from == 0.0f &&
+			    camera->stereo.pole_merge_angle_to == 0.0f)
+			{
+				camera->stereo.pole_merge_angle_from = DEG2RAD(60.0f);
+				camera->stereo.pole_merge_angle_to = DEG2RAD(75.0f);
+			}
+		}
+	}
 }
diff --git a/source/blender/makesdna/DNA_camera_types.h b/source/blender/makesdna/DNA_camera_types.h
index 7f2e1aaadf9..68741578f27 100644
--- a/source/blender/makesdna/DNA_camera_types.h
+++ b/source/blender/makesdna/DNA_camera_types.h
@@ -53,6 +53,10 @@ typedef struct CameraStereoSettings {
 	short pivot;
 	short flag;
 	short pad;
+	/* Cut-off angle at which interocular distance start to fade down. */
+	float pole_merge_angle_from;
+	/* Cut-off angle at which interocular distance stops to fade down. */
+	float pole_merge_angle_to;
 } CameraStereoSettings;
 
 typedef struct Camera {
@@ -152,6 +156,7 @@ enum {
 /* stereo->flag */
 enum {
 	CAM_S3D_SPHERICAL       = (1 << 0),
+	CAM_S3D_POLE_MERGE      = (1 << 1),
 };
 
 #ifdef __cplusplus
diff --git a/source/blender/makesrna/intern/rna_camera.c b/source/blender/makesrna/intern/rna_camera.c
index fd81f3aa46c..dcb4d65f3f9 100644
--- a/source/blender/makesrna/intern/rna_camera.c
+++ b/source/blender/makesrna/intern/rna_camera.c
@@ -151,6 +151,24 @@ static void rna_def_camera_stereo_data(BlenderRNA *brna)
 	                         "Render every pixel rotating the camera around the "
 	                         "middle of the interocular distance");
 	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
+
+	prop = RNA_def_property(srna, "use_pole_merge", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "flag", CAM_S3D_POLE_MERGE);
+	RNA_def_property_ui_text(prop, "Use Pole Merge",
+	                         "Fade interocular distance to 0 after the given cutoff angle");
+	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
+
+	prop = RNA_def_property(srna, "pole_merge_angle_from", PROP_FLOAT, PROP_ANGLE);
+	RNA_def_property_range(prop, 0.0f, M_PI / 2.0f);
+	RNA_def_property_ui_text(prop, "Pole Merge Start Angle",
+	                         "Angle at which interocular distance starts to fade to 0");
+	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
+
+	prop = RNA_def_property(srna, "pole_merge_angle_to", PROP_FLOAT, PROP_ANGLE);
+	RNA_def_property_range(prop, 0.0f, M_PI / 2.0f);
+	RNA_def_property_ui_text(prop, "Pole Merge End Angle",
+	                         "Angle at which interocular distance is 0");
+	RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
 }
 
 void RNA_def_camera(BlenderRNA *brna)