Cycles: Adding field-of-view options to the equirectangular panorama camera

This patch adds the option to set minimum/maximum latitude/longitude values for
the equirectangular panorama camera in Cycles, as discussed in T34400.

The separate functions in kernel_projection.h are needed because the regular
ones are also used as helper functions for environment map sampling.

Reviewers: #cycles, sergey

Reviewed By: #cycles, sergey

Subscribers: dingto, sergey, brecht

Differential Revision: https://developer.blender.org/D960

6 files changed, 75 insertions, 9 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index b61cc66b83c..10c5f2bb58c 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -582,6 +582,34 @@ class CyclesCameraSettings(bpy.types.PropertyGroup):
                 min=0.01, soft_max=15.0, max=100.0,
                 default=10.5,
                 )
+        cls.latitude_min = FloatProperty(
+                name="Min latitude",
+                description="Minimum latitude (vertical angle) for the equirectangular lens",
+                min=-0.5 * math.pi, max=0.5 * math.pi,
+                subtype='ANGLE',
+                default=-0.5 * math.pi,
+                )
+        cls.latitude_max = FloatProperty(
+                name="Max latitude",
+                description="Maximum latitude (vertical angle) for the equirectangular lens",
+                min=-0.5 * math.pi, max=0.5 * math.pi,
+                subtype='ANGLE',
+                default=0.5 * math.pi,
+                )
+        cls.longitude_min = FloatProperty(
+                name="Min longitude",
+                description="Minimum longitude (horizontal angle) for the equirectangular lens",
+                min=-math.pi, max=math.pi,
+                subtype='ANGLE',
+                default=-math.pi,
+                )
+        cls.longitude_max = FloatProperty(
+                name="Max longitude",
+                description="Maximum longitude (horizontal angle) for the equirectangular lens",
+                min=-math.pi, max=math.pi,
+                subtype='ANGLE',
+                default=math.pi,
+                )
 
     @classmethod
     def unregister(cls):
diff --git a/intern/cycles/blender/blender_camera.cpp b/intern/cycles/blender/blender_camera.cpp
index ad98c062d25..e5214fb5c30 100644
--- a/intern/cycles/blender/blender_camera.cpp
+++ b/intern/cycles/blender/blender_camera.cpp
@@ -53,6 +53,10 @@ struct BlenderCamera {
 	PanoramaType panorama_type;
 	float fisheye_fov;
 	float fisheye_lens;
+	float latitude_min;
+	float latitude_max;
+	float longitude_min;
+	float longitude_max;
 
 	enum { AUTO, HORIZONTAL, VERTICAL } sensor_fit;
 	float sensor_width;
@@ -147,6 +151,10 @@ static void blender_camera_from_object(BlenderCamera *bcam, BL::Object b_ob, boo
 
 		bcam->fisheye_fov = RNA_float_get(&ccamera, "fisheye_fov");
 		bcam->fisheye_lens = RNA_float_get(&ccamera, "fisheye_lens");
+		bcam->latitude_min = RNA_float_get(&ccamera, "latitude_min");
+		bcam->latitude_max = RNA_float_get(&ccamera, "latitude_max");
+		bcam->longitude_min = RNA_float_get(&ccamera, "longitude_min");
+		bcam->longitude_max = RNA_float_get(&ccamera, "longitude_max");
 
 		bcam->ortho_scale = b_camera.ortho_scale();
 
@@ -332,6 +340,11 @@ static void blender_camera_sync(Camera *cam, BlenderCamera *bcam, int width, int
 	cam->panorama_type = bcam->panorama_type;
 	cam->fisheye_fov = bcam->fisheye_fov;
 	cam->fisheye_lens = bcam->fisheye_lens;
+	cam->latitude_min = bcam->latitude_min;
+	cam->latitude_max = bcam->latitude_max;
+
+	cam->longitude_min = bcam->longitude_min;
+	cam->longitude_max = bcam->longitude_max;
 
 	/* anamorphic lens bokeh */
 	cam->aperture_ratio = bcam->aperture_ratio;
diff --git a/intern/cycles/kernel/kernel_projection.h b/intern/cycles/kernel/kernel_projection.h
index 6744471d659..ab63f460371 100644
--- a/intern/cycles/kernel/kernel_projection.h
+++ b/intern/cycles/kernel/kernel_projection.h
@@ -55,18 +55,18 @@ ccl_device float3 spherical_to_direction(float theta, float phi)
 
 /* Equirectangular coordinates <-> Cartesian direction */
 
-ccl_device float2 direction_to_equirectangular(float3 dir)
+ccl_device float2 direction_to_equirectangular_range(float3 dir, float4 range)
 {
-	float u = -atan2f(dir.y, dir.x)/(M_2PI_F) + 0.5f;
-	float v = atan2f(dir.z, hypotf(dir.x, dir.y))/M_PI_F + 0.5f;
+	float u = (atan2f(dir.y, dir.x) - range.y) / range.x;
+	float v = (acosf(dir.z / len(dir)) - range.w) / range.z;
 
 	return make_float2(u, v);
 }
 
-ccl_device float3 equirectangular_to_direction(float u, float v)
+ccl_device float3 equirectangular_range_to_direction(float u, float v, float4 range)
 {
-	float phi = M_PI_F*(1.0f - 2.0f*u);
-	float theta = M_PI_F*(1.0f - v);
+	float phi = range.x*u + range.y;
+	float theta = range.z*v + range.w;
 
 	return make_float3(
 		sinf(theta)*cosf(phi),
@@ -74,6 +74,16 @@ ccl_device float3 equirectangular_to_direction(float u, float v)
 		cosf(theta));
 }
 
+ccl_device float2 direction_to_equirectangular(float3 dir)
+{
+	return direction_to_equirectangular_range(dir, make_float4(-M_2_PI_F, M_PI_F, -M_PI_F, M_PI_F));
+}
+
+ccl_device float3 equirectangular_to_direction(float u, float v)
+{
+	return equirectangular_range_to_direction(u, v, make_float4(-M_2_PI_F, M_PI_F, -M_PI_F, M_PI_F));
+}
+
 /* Fisheye <-> Cartesian direction */
 
 ccl_device float2 direction_to_fisheye(float3 dir, float fov)
@@ -180,7 +190,7 @@ ccl_device float3 panorama_to_direction(KernelGlobals *kg, float u, float v)
 {
 	switch(kernel_data.cam.panorama_type) {
 		case PANORAMA_EQUIRECTANGULAR:
-			return equirectangular_to_direction(u, v);
+			return equirectangular_range_to_direction(u, v, kernel_data.cam.equirectangular_range);
 		case PANORAMA_FISHEYE_EQUIDISTANT:
 			return fisheye_to_direction(u, v, kernel_data.cam.fisheye_fov);
 		case PANORAMA_FISHEYE_EQUISOLID:
@@ -194,7 +204,7 @@ ccl_device float2 direction_to_panorama(KernelGlobals *kg, float3 dir)
 {
 	switch(kernel_data.cam.panorama_type) {
 		case PANORAMA_EQUIRECTANGULAR:
-			return direction_to_equirectangular(dir);
+			return direction_to_equirectangular_range(dir, kernel_data.cam.equirectangular_range);
 		case PANORAMA_FISHEYE_EQUIDISTANT:
 			return direction_to_fisheye(dir, kernel_data.cam.fisheye_fov);
 		case PANORAMA_FISHEYE_EQUISOLID:
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index a230acb2fbc..77d3ea874d0 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -767,6 +767,7 @@ typedef struct KernelCamera {
 	int panorama_type;
 	float fisheye_fov;
 	float fisheye_lens;
+	float4 equirectangular_range;
 
 	/* matrices */
 	Transform cameratoworld;
diff --git a/intern/cycles/render/camera.cpp b/intern/cycles/render/camera.cpp
index 54f1be2f384..5b0d51e60c2 100644
--- a/intern/cycles/render/camera.cpp
+++ b/intern/cycles/render/camera.cpp
@@ -47,6 +47,10 @@ Camera::Camera()
 	panorama_type = PANORAMA_EQUIRECTANGULAR;
 	fisheye_fov = M_PI_F;
 	fisheye_lens = 10.5f;
+	latitude_min = -M_PI_2_F;
+	latitude_max = M_PI_2_F;
+	longitude_min = -M_PI_F;
+	longitude_max = M_PI_F;
 	fov = M_PI_4_F;
 
 	sensorwidth = 0.036f;
@@ -253,6 +257,8 @@ void Camera::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 	kcam->panorama_type = panorama_type;
 	kcam->fisheye_fov = fisheye_fov;
 	kcam->fisheye_lens = fisheye_lens;
+	kcam->equirectangular_range = make_float4(longitude_min - longitude_max, -longitude_min,
+	                                          latitude_min -  latitude_max, -latitude_min + M_PI_2_F);
 
 	/* sensor size */
 	kcam->sensorwidth = sensorwidth;
@@ -316,7 +322,11 @@ bool Camera::modified(const Camera& cam)
 		(aperture_ratio == cam.aperture_ratio) &&
 		(panorama_type == cam.panorama_type) &&
 		(fisheye_fov == cam.fisheye_fov) &&
-		(fisheye_lens == cam.fisheye_lens));
+		(fisheye_lens == cam.fisheye_lens) &&
+		(latitude_min == cam.latitude_min) &&
+		(latitude_max == cam.latitude_max) &&
+		(longitude_min == cam.longitude_min) &&
+		(longitude_max == cam.longitude_max));
 }
 
 bool Camera::motion_modified(const Camera& cam)
diff --git a/intern/cycles/render/camera.h b/intern/cycles/render/camera.h
index f809c060741..9525cce8109 100644
--- a/intern/cycles/render/camera.h
+++ b/intern/cycles/render/camera.h
@@ -53,6 +53,10 @@ public:
 	PanoramaType panorama_type;
 	float fisheye_fov;
 	float fisheye_lens;
+	float latitude_min;
+	float latitude_max;
+	float longitude_min;
+	float longitude_max;
 
 	/* anamorphic lens bokeh */
 	float aperture_ratio;