Manipulator: experimental lamp positioning tool

- New manipulator tracks lamps to position under cursor.
- Works with multiple lamps, keeping relative offsets.
- Holding Ctrl moves the lamp.
- Access via manipulator or Shift-T.

Code could be improved, but like to get feedback from users.

3 files changed, 388 insertions, 0 deletions

diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index f6fb3cc75b8..3e655fa04a4 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -55,6 +55,7 @@ void OBJECT_OT_scale_clear(struct wmOperatorType *ot);
 void OBJECT_OT_origin_clear(struct wmOperatorType *ot);
 void OBJECT_OT_visual_transform_apply(struct wmOperatorType *ot);
 void OBJECT_OT_transform_apply(struct wmOperatorType *ot);
+void OBJECT_OT_transform_axis_target(struct wmOperatorType *ot);
 void OBJECT_OT_origin_set(struct wmOperatorType *ot);
 
 /* object_relations.c */
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index ca02457ba39..07922f2d3b2 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -61,6 +61,7 @@ void ED_operatortypes_object(void)
 	WM_operatortype_append(OBJECT_OT_origin_clear);
 	WM_operatortype_append(OBJECT_OT_visual_transform_apply);
 	WM_operatortype_append(OBJECT_OT_transform_apply);
+	WM_operatortype_append(OBJECT_OT_transform_axis_target);
 	WM_operatortype_append(OBJECT_OT_origin_set);
 	
 	WM_operatortype_append(OBJECT_OT_mode_set);
diff --git a/source/blender/editors/object/object_transform.c b/source/blender/editors/object/object_transform.c
index 19f9c779132..cf68bd3e419 100644
--- a/source/blender/editors/object/object_transform.c
+++ b/source/blender/editors/object/object_transform.c
@@ -39,10 +39,12 @@
 #include "DNA_scene_types.h"
 #include "DNA_group_types.h"
 #include "DNA_lattice_types.h"
+#include "DNA_lamp_types.h"
 
 #include "BLI_math.h"
 #include "BLI_listbase.h"
 #include "BLI_utildefines.h"
+#include "BLI_array.h"
 
 #include "BKE_context.h"
 #include "BKE_curve.h"
@@ -72,6 +74,8 @@
 #include "ED_screen.h"
 #include "ED_view3d.h"
 
+#include "MEM_guardedalloc.h"
+
 #include "object_intern.h"
 
 /*************************** Clear Transformation ****************************/
@@ -1124,3 +1128,385 @@ void OBJECT_OT_origin_set(wmOperatorType *ot)
 	ot->prop = RNA_def_enum(ot->srna, "type", prop_set_center_types, 0, "Type", "");
 	RNA_def_enum(ot->srna, "center", prop_set_bounds_types, V3D_AROUND_CENTER_MEAN, "Center", "");
 }
+
+/* -------------------------------------------------------------------- */
+
+/** \name Transform Axis Target
+ *
+ * Note this is an experemental operator to point lamps/cameras at objects.
+ * We may re-work how this behaves based on user feedback.
+ * - campbell.
+ * \{ */
+
+/* When using multiple objects, apply their relative rotational offset to the active object. */
+#define USE_RELATIVE_ROTATION
+
+struct XFormAxisItem {
+	Object *ob;
+	float rot_mat[3][3];
+	void *obtfm;
+	float xform_dist;
+
+#ifdef USE_RELATIVE_ROTATION
+	/* use when translating multiple */
+	float xform_rot_offset[3][3];
+#endif
+};
+
+struct XFormAxisData {
+	ViewContext vc;
+	struct {
+		float depth;
+		float normal[3];
+		bool is_depth_valid;
+		bool is_normal_valid;
+	} prev;
+
+	struct XFormAxisItem *object_data;
+	uint object_data_len;
+	bool is_translate;
+
+	int init_event;
+};
+
+static bool object_is_target_compat(const Object *ob)
+{
+	if (ob->type == OB_LAMP) {
+		const Lamp *la = ob->data;
+		if (ELEM(la->type, LA_SUN, LA_SPOT, LA_HEMI, LA_AREA)) {
+			return true;
+		}
+	}
+	/* We might want to enable this later, for now just lamps */
+#if 0
+	else if (ob->type == OB_CAMERA) {
+		return true;
+	}
+#endif
+	return false;
+}
+
+static void object_transform_axis_target_free_data(wmOperator *op)
+{
+	struct XFormAxisData *xfd = op->customdata;
+	struct XFormAxisItem *item = xfd->object_data;
+	for (int i = 0; i < xfd->object_data_len; i++, item++) {
+		MEM_freeN(item->obtfm);
+	}
+	MEM_freeN(xfd->object_data);
+	MEM_freeN(xfd);
+	op->customdata = NULL;
+}
+
+/* We may want to expose as alternative to: BKE_object_apply_rotation */
+static void object_apply_rotation(Object *ob, const float rmat[3][3])
+{
+	float size[3];
+	float loc[3];
+	float rmat4[4][4];
+	copy_m4_m3(rmat4, rmat);
+
+	copy_v3_v3(size, ob->size);
+	copy_v3_v3(loc, ob->loc);
+	BKE_object_apply_mat4(ob, rmat4, true, true);
+	copy_v3_v3(ob->size, size);
+	copy_v3_v3(ob->loc, loc);
+}
+/* We may want to extract this to: BKE_object_apply_location */
+static void object_apply_location(Object *ob, const float loc[3])
+{
+	/* quick but weak */
+	Object ob_prev = *ob;
+	float mat[4][4];
+	copy_m4_m4(mat, ob->obmat);
+	copy_v3_v3(mat[3], loc);
+	BKE_object_apply_mat4(ob, mat, true, true);
+	copy_v3_v3(mat[3], ob->loc);
+	*ob = ob_prev;
+	copy_v3_v3(ob->loc, mat[3]);
+}
+
+static void object_orient_to_location(
+        Object *ob, float rot_orig[3][3], const float axis[3], const float location[3])
+{
+	float delta[3];
+	sub_v3_v3v3(delta, ob->obmat[3], location);
+	if (normalize_v3(delta) != 0.0f) {
+		if (len_squared_v3v3(delta, axis) > FLT_EPSILON) {
+			float delta_rot[3][3];
+			float final_rot[3][3];
+			rotation_between_vecs_to_mat3(delta_rot, axis, delta);
+
+			mul_m3_m3m3(final_rot, delta_rot, rot_orig);
+
+			object_apply_rotation(ob, final_rot);
+
+			DEG_id_tag_update(&ob->id, OB_RECALC_OB);
+		}
+	}
+}
+
+static void object_transform_axis_target_cancel(bContext *C, wmOperator *op)
+{
+	struct XFormAxisData *xfd = op->customdata;
+	struct XFormAxisItem *item = xfd->object_data;
+	for (int i = 0; i < xfd->object_data_len; i++, item++) {
+		BKE_object_tfm_restore(item->ob, item->obtfm);
+		DEG_id_tag_update(&item->ob->id, OB_RECALC_OB);
+		WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, item->ob);
+	}
+
+	object_transform_axis_target_free_data(op);
+}
+
+static int object_transform_axis_target_invoke(bContext *C, wmOperator *op, const wmEvent *event)
+{
+	ViewContext vc;
+	view3d_set_viewcontext(C, &vc);
+
+	if (!object_is_target_compat(vc.obact)) {
+		/* Falls back to texture space transform. */
+		return OPERATOR_PASS_THROUGH;
+	}
+
+	ED_view3d_autodist_init(C, vc.depsgraph, vc.ar, vc.v3d, 0);
+
+	if (vc.rv3d->depths != NULL) {
+		vc.rv3d->depths->damaged = true;
+	}
+	ED_view3d_depth_update(vc.ar);
+
+	if (vc.rv3d->depths == NULL) {
+		BKE_report(op->reports, RPT_WARNING, "Unable to access depth buffer, using view plane");
+		return OPERATOR_CANCELLED;
+	}
+
+	ED_region_tag_redraw(vc.ar);
+
+	struct XFormAxisData *xfd;
+	xfd = op->customdata = MEM_callocN(sizeof(struct XFormAxisData), __func__);
+
+	/* Don't change this at runtime. */
+	xfd->vc = vc;
+	xfd->vc.mval[0] = event->mval[0];
+	xfd->vc.mval[1] = event->mval[1];
+
+	xfd->prev.depth = 1.0f;
+	xfd->prev.is_depth_valid = false;
+	xfd->prev.is_normal_valid = false;
+	xfd->is_translate = false;
+
+	xfd->init_event = WM_userdef_event_type_from_keymap_type(event->type);
+
+	{
+		struct XFormAxisItem *object_data = NULL;
+		BLI_array_declare(object_data);
+
+		struct XFormAxisItem *item = BLI_array_append_ret(object_data);
+		item->ob = xfd->vc.obact;
+
+		CTX_DATA_BEGIN (C, Object *, ob, selected_editable_objects)
+		{
+			if ((ob != xfd->vc.obact) && object_is_target_compat(ob)) {
+				item = BLI_array_append_ret(object_data);
+				item->ob = ob;
+			}
+		}
+		CTX_DATA_END;
+
+		xfd->object_data = object_data;
+		xfd->object_data_len = BLI_array_count(object_data);
+
+		if (xfd->object_data_len != BLI_array_count(object_data)) {
+			xfd->object_data = MEM_reallocN(xfd->object_data, xfd->object_data_len * sizeof(*xfd->object_data));
+		}
+	}
+
+	{
+		struct XFormAxisItem *item = xfd->object_data;
+		for (int i = 0; i < xfd->object_data_len; i++, item++) {
+			item->obtfm = BKE_object_tfm_backup(item->ob);
+			BKE_object_rot_to_mat3(item->ob, item->rot_mat, true);
+		}
+	}
+
+	WM_event_add_modal_handler(C, op);
+
+	return OPERATOR_RUNNING_MODAL;
+}
+
+static int object_transform_axis_target_modal(bContext *C, wmOperator *op, const wmEvent *event)
+{
+	struct XFormAxisData *xfd = op->customdata;
+	ARegion *ar = xfd->vc.ar;
+
+	view3d_operator_needs_opengl(C);
+
+	const bool is_translate = (event->ctrl != 0);
+	const bool is_translate_init = is_translate && (xfd->is_translate != is_translate);
+
+	if (event->type == MOUSEMOVE || is_translate_init) {
+		const ViewDepths *depths = xfd->vc.rv3d->depths;
+		if (depths &&
+		    ((unsigned int)event->mval[0] < depths->w) &&
+		    ((unsigned int)event->mval[1] < depths->h))
+		{
+			double depth = (double)ED_view3d_depth_read_cached(&xfd->vc, event->mval);
+			float location_world[3];
+			if (depth == 1.0f) {
+				if (xfd->prev.is_depth_valid) {
+					depth = (double)xfd->prev.depth;
+				}
+			}
+			if ((depth > depths->depth_range[0]) && (depth < depths->depth_range[1])) {
+				xfd->prev.depth = depth;
+				xfd->prev.is_depth_valid = true;
+				if (ED_view3d_depth_unproject(ar, event->mval, depth, location_world)) {
+					if (is_translate) {
+
+						float normal[3];
+						bool normal_found = false;
+						if (ED_view3d_depth_read_cached_normal(&xfd->vc, event->mval, normal)) {
+							normal_found = true;
+
+							/* cheap attempt to smooth normals out a bit! */
+							const uint ofs = 2;
+							for (uint x = -ofs; x <= ofs; x += ofs / 2) {
+								for (uint y = -ofs; y <= ofs; y += ofs / 2) {
+									if (x != 0 && y != 0) {
+										int mval_ofs[2] = {event->mval[0] + x, event->mval[1] + y};
+										float n[3];
+										if (ED_view3d_depth_read_cached_normal(
+										        &xfd->vc, mval_ofs, n))
+										{
+											add_v3_v3(normal, n);
+										}
+									}
+								}
+							}
+							normalize_v3(normal);
+						}
+						else if (xfd->prev.is_normal_valid) {
+							copy_v3_v3(normal, xfd->prev.normal);
+							normal_found = true;
+						}
+
+						if (normal_found) {
+#ifdef USE_RELATIVE_ROTATION
+							if (is_translate_init && xfd->object_data_len > 1) {
+								float xform_rot_offset_inv_first[3][3];
+								struct XFormAxisItem *item = xfd->object_data;
+								for (int i = 0; i < xfd->object_data_len; i++, item++) {
+									copy_m3_m4(item->xform_rot_offset, item->ob->obmat);
+									normalize_m3(item->xform_rot_offset);
+
+									if (i == 0) {
+										invert_m3_m3(xform_rot_offset_inv_first, xfd->object_data[0].xform_rot_offset);
+									}
+									else {
+										mul_m3_m3m3(item->xform_rot_offset,
+										            item->xform_rot_offset,
+										            xform_rot_offset_inv_first);
+									}
+								}
+							}
+
+#endif
+
+							struct XFormAxisItem *item = xfd->object_data;
+							for (int i = 0; i < xfd->object_data_len; i++, item++) {
+								if (is_translate_init) {
+									float ob_axis[3];
+									item->xform_dist = len_v3v3(item->ob->obmat[3], location_world);
+									normalize_v3_v3(ob_axis, item->ob->obmat[2]);
+									/* Scale to avoid adding distance when moving between surfaces. */
+									float scale = fabsf(dot_v3v3(ob_axis, normal));
+									item->xform_dist *= scale;
+								}
+
+								float target_normal[3];
+								copy_v3_v3(target_normal, normal);
+
+#ifdef USE_RELATIVE_ROTATION
+								if (i != 0) {
+									mul_m3_v3(item->xform_rot_offset, target_normal);
+								}
+#endif
+								{
+									float loc[3];
+
+									copy_v3_v3(loc, location_world);
+									madd_v3_v3fl(loc, target_normal, item->xform_dist);
+									object_apply_location(item->ob, loc);
+									copy_v3_v3(item->ob->obmat[3], loc);  /* so orient behaves as expected */
+								}
+
+								object_orient_to_location(item->ob, item->rot_mat, item->rot_mat[2], location_world);
+								WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, item->ob);
+							}
+							copy_v3_v3(xfd->prev.normal, normal);
+							xfd->prev.is_normal_valid = true;
+						}
+					}
+					else {
+						struct XFormAxisItem *item = xfd->object_data;
+						for (int i = 0; i < xfd->object_data_len; i++, item++) {
+							object_orient_to_location(item->ob, item->rot_mat, item->rot_mat[2], location_world);
+							WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, item->ob);
+						}
+						xfd->prev.is_normal_valid = false;
+					}
+				}
+			}
+		}
+		xfd->is_translate = is_translate;
+
+		ED_region_tag_redraw(xfd->vc.ar);
+	}
+
+	bool is_finished = false;
+
+	if (ISMOUSE(xfd->init_event)) {
+		if ((event->type == xfd->init_event) && (event->val == KM_RELEASE)) {
+			is_finished = true;
+		}
+	}
+	else {
+		if (ELEM(event->type, LEFTMOUSE, RETKEY, PADENTER)) {
+			is_finished = true;
+		}
+	}
+
+	if (is_finished) {
+		object_transform_axis_target_free_data(op);
+		return OPERATOR_FINISHED;
+	}
+	else if (ELEM(event->type, ESCKEY, RIGHTMOUSE)) {
+		object_transform_axis_target_cancel(C, op);
+		return OPERATOR_CANCELLED;
+	}
+
+
+	return OPERATOR_RUNNING_MODAL;
+}
+
+void OBJECT_OT_transform_axis_target(wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name = "Interactive Lamp Track to Cursor";
+	ot->description = "Interactively point cameras and lamps to a location (Ctrl translates)";
+	ot->idname = "OBJECT_OT_transform_axis_target";
+
+	/* api callbacks */
+	ot->invoke = object_transform_axis_target_invoke;
+	ot->cancel = object_transform_axis_target_cancel;
+	ot->modal = object_transform_axis_target_modal;
+	ot->poll = ED_operator_region_view3d_active;
+
+	/* flags */
+	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_BLOCKING;
+}
+
+#undef USE_RELATIVE_ROTATION
+
+/** \} */