Curve Decimate: new tool to simplify bezier curves

Access from the curve clean-up menu

7 files changed, 439 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_curve.h b/source/blender/blenkernel/BKE_curve.h
index a900ba43443..30db8f45059 100644
--- a/source/blender/blenkernel/BKE_curve.h
+++ b/source/blender/blenkernel/BKE_curve.h
@@ -218,4 +218,14 @@ struct EvaluationContext;
 void BKE_curve_eval_geometry(struct EvaluationContext *eval_ctx,
                              struct Curve *curve);
 
+/* curve_decimate.c */
+unsigned int BKE_curve_decimate_bezt_array(
+        struct BezTriple *bezt_array, const unsigned int bezt_array_len, const unsigned int resolu, const bool is_cyclic,
+        const char flag_test, const char flag_set,
+        const float error_sq_max, const unsigned int error_target_len);
+
+void BKE_curve_decimate_nurb(
+        struct Nurb *nu, const unsigned int resolu,
+        const float error_sq_max, const unsigned int error_target_len);
+
 #endif  /* __BKE_CURVE_H__ */
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 51598ede862..74c69c5aeb9 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -49,6 +49,7 @@ set(INC
 	../../../intern/smoke/extern
 	../../../intern/atomic
 	../../../intern/libmv
+	../../../extern/curve_fit_nd
 )
 
 set(INC_SYS
@@ -91,6 +92,7 @@ set(SRC
 	intern/context.c
 	intern/crazyspace.c
 	intern/curve.c
+	intern/curve_decimate.c
 	intern/customdata.c
 	intern/customdata_file.c
 	intern/data_transfer.c
diff --git a/source/blender/blenkernel/intern/curve_decimate.c b/source/blender/blenkernel/intern/curve_decimate.c
new file mode 100644
index 00000000000..7983c63c99d
--- /dev/null
+++ b/source/blender/blenkernel/intern/curve_decimate.c
@@ -0,0 +1,339 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/curve_decimate.c
+ *  \ingroup bke
+ */
+
+#include "DNA_curve_types.h"
+
+#include "MEM_guardedalloc.h"
+#include "BLI_heap.h"
+#include "BLI_math_vector.h"
+
+#include "BKE_curve.h"
+
+#include "curve_fit_nd.h"
+
+#include "BLI_strict_flags.h"
+
+struct Knot {
+	struct Knot *next, *prev;
+	uint point_index;  /* index in point array */
+	uint knot_index;  /* index in knot array*/
+	float tan[2][3];
+	float handles[2];
+
+	HeapNode *heap_node;
+	uint can_remove : 1;
+	uint is_removed : 1;
+
+#ifndef NDEBUG
+	const float *co;
+#endif
+};
+
+struct Removal {
+	uint knot_index;
+	/* handles for prev/next knots */
+	float handles[2];
+};
+
+static float knot_remove_error_value(
+        const float tan_l[3], const float tan_r[3],
+        const float (*points)[3], const uint points_len,
+        /* avoid having to re-calculate again */
+        float r_handle_factors[2])
+{
+	const uint dims = 3;
+	float error_sq = FLT_MAX;
+	uint error_sq_index;
+	float handle_factors[2][3];
+
+	curve_fit_cubic_to_points_single_fl(
+	        &points[0][0], points_len, NULL, dims, 0.0f,
+	        tan_l, tan_r,
+	        handle_factors[0], handle_factors[1],
+	        &error_sq, &error_sq_index);
+
+	sub_v3_v3(handle_factors[0], points[0]);
+	r_handle_factors[0] = dot_v3v3(tan_l, handle_factors[0]);
+
+	sub_v3_v3(handle_factors[1], points[points_len - 1]);
+	r_handle_factors[1] = dot_v3v3(tan_r, handle_factors[1]);
+
+	return error_sq;
+}
+
+static void knot_remove_error_recalculate(
+        Heap *heap, const float (*points)[3], const uint points_len,
+        struct Knot *k, const float error_sq_max)
+{
+	BLI_assert(k->can_remove);
+	float handles[2];
+
+#ifndef NDEBUG
+	BLI_assert(equals_v3v3(points[k->prev->point_index], k->prev->co));
+	BLI_assert(equals_v3v3(points[k->next->point_index], k->next->co));
+#endif
+
+	const float (*points_offset)[3];
+	uint points_offset_len;
+
+	if (k->prev->point_index < k->next->point_index) {
+		points_offset = &points[k->prev->point_index];
+		points_offset_len = (k->next->point_index - k->prev->point_index) + 1;
+	}
+	else {
+		points_offset = &points[k->prev->point_index];
+		points_offset_len = ((k->next->point_index + points_len) - k->prev->point_index) + 1;
+	}
+
+	const float cost_sq = knot_remove_error_value(
+	        k->prev->tan[1], k->next->tan[0],
+	        points_offset, points_offset_len,
+	        handles);
+
+	if (cost_sq < error_sq_max) {
+		struct Removal *r;
+		if (k->heap_node) {
+			r = BLI_heap_node_ptr(k->heap_node);
+		}
+		else {
+			r = MEM_mallocN(sizeof(*r), __func__);
+			r->knot_index = k->knot_index;
+		}
+
+		copy_v2_v2(r->handles, handles);
+
+		BLI_heap_insert_or_update(heap, &k->heap_node, cost_sq, r);
+	}
+	else {
+		if (k->heap_node) {
+			struct Removal *r;
+			r = BLI_heap_node_ptr(k->heap_node);
+			BLI_heap_remove(heap, k->heap_node);
+
+			MEM_freeN(r);
+
+			k->heap_node = NULL;
+		}
+	}
+}
+
+static void curve_decimate(
+        const float (*points)[3], const uint points_len,
+        struct Knot *knots, const uint knots_len,
+        float error_sq_max, const uint error_target_len)
+{
+	Heap *heap = BLI_heap_new_ex(knots_len);
+	for (uint i = 0; i < knots_len; i++) {
+		struct Knot *k = &knots[i];
+		if (k->can_remove) {
+			knot_remove_error_recalculate(heap, points, points_len, k, error_sq_max);
+		}
+	}
+
+	uint knots_len_remaining = knots_len;
+
+	while ((knots_len_remaining > error_target_len) &&
+	       (BLI_heap_is_empty(heap) == false))
+	{
+		struct Knot *k;
+
+		{
+			struct Removal *r = BLI_heap_popmin(heap);
+			k = &knots[r->knot_index];
+			k->heap_node = NULL;
+			k->prev->handles[1] = r->handles[0];
+			k->next->handles[0] = r->handles[1];
+			MEM_freeN(r);
+		}
+
+		struct Knot *k_prev = k->prev;
+		struct Knot *k_next = k->next;
+
+		/* remove ourselves */
+		k_next->prev = k_prev;
+		k_prev->next = k_next;
+
+		k->next = NULL;
+		k->prev = NULL;
+		k->is_removed = true;
+
+		if (k_prev->can_remove) {
+			knot_remove_error_recalculate(heap, points, points_len, k_prev, error_sq_max);
+		}
+
+		if (k_next->can_remove) {
+			knot_remove_error_recalculate(heap, points, points_len, k_next, error_sq_max);
+		}
+
+		knots_len_remaining -= 1;
+	}
+
+	BLI_heap_free(heap, MEM_freeN);
+}
+
+
+uint BKE_curve_decimate_bezt_array(
+        BezTriple *bezt_array, const uint bezt_array_len,
+        const uint resolu, const bool is_cyclic,
+        const char flag_test, const char flag_set,
+        const float error_sq_max, const uint error_target_len)
+{
+	const uint bezt_array_last = bezt_array_len - 1;
+	const uint points_len = BKE_curve_calc_coords_axis_len(bezt_array_len, resolu, is_cyclic, true);
+
+	float (*points)[3] = MEM_mallocN((sizeof(float[3]) * points_len * (is_cyclic ? 2 : 1)), __func__);
+
+	BKE_curve_calc_coords_axis(bezt_array, bezt_array_len, resolu, is_cyclic, false, 0, sizeof(float[3]), &points[0][0]);
+	BKE_curve_calc_coords_axis(bezt_array, bezt_array_len, resolu, is_cyclic, false, 1, sizeof(float[3]), &points[0][1]);
+	BKE_curve_calc_coords_axis(bezt_array, bezt_array_len, resolu, is_cyclic, false, 2, sizeof(float[3]), &points[0][2]);
+
+	const uint knots_len = bezt_array_len;
+	struct Knot *knots = MEM_mallocN((sizeof(*knots) * bezt_array_len), __func__);
+
+	if (is_cyclic) {
+		memcpy(points[points_len], points[0], sizeof(float[3]) * points_len);
+	}
+
+	for (uint i = 0; i < bezt_array_len; i++) {
+		knots[i].heap_node = NULL;
+		knots[i].can_remove = (bezt_array[i].f2 & flag_test) != 0;
+		knots[i].is_removed = false;
+		knots[i].next = &knots[i + 1];
+		knots[i].prev = &knots[i - 1];
+		knots[i].point_index = i * resolu;
+		knots[i].knot_index = i;
+
+		sub_v3_v3v3(knots[i].tan[0], bezt_array[i].vec[0], bezt_array[i].vec[1]);
+		knots[i].handles[0] = normalize_v3(knots[i].tan[0]);
+
+		sub_v3_v3v3(knots[i].tan[1], bezt_array[i].vec[1], bezt_array[i].vec[2]);
+		knots[i].handles[1] = -normalize_v3(knots[i].tan[1]);
+
+#ifndef NDEBUG
+		knots[i].co = bezt_array[i].vec[1];
+		BLI_assert(equals_v3v3(knots[i].co, points[knots[i].point_index]));
+#endif
+	}
+
+	if (is_cyclic) {
+		knots[0].prev = &knots[bezt_array_last];
+		knots[bezt_array_last].next = &knots[0];
+	}
+	else {
+		knots[0].prev = NULL;
+		knots[bezt_array_last].next = NULL;
+
+		/* always keep end-points */
+		knots[0].can_remove = false;
+		knots[bezt_array_last].can_remove = false;
+	}
+
+	curve_decimate(points, points_len, knots, knots_len, error_sq_max, error_target_len);
+
+	MEM_freeN(points);
+
+	uint knots_len_decimated = knots_len;
+
+	/* Update handle type on modifications. */
+#define HANDLE_UPDATE(a, b) \
+	{ \
+		if (a == HD_VECT) { \
+			a = HD_FREE; \
+		} \
+		else if (a == HD_AUTO) { \
+			a = HD_ALIGN; \
+		} \
+		/* opposite handle */ \
+		if (b == HD_AUTO) { \
+			b = HD_ALIGN; \
+		} \
+	} ((void)0)
+
+	for (uint i = 0; i < bezt_array_len; i++) {
+		if (knots[i].is_removed) {
+			/* caller must remove */
+			bezt_array[i].f2 |= flag_set;
+			knots_len_decimated--;
+		}
+		else {
+			bezt_array[i].f2 &= (char)~flag_set;
+			if (is_cyclic || i != 0) {
+				uint i_prev = (i != 0) ? i - 1 : bezt_array_last;
+				if (knots[i_prev].is_removed) {
+					madd_v3_v3v3fl(bezt_array[i].vec[0], bezt_array[i].vec[1], knots[i].tan[0], knots[i].handles[0]);
+					HANDLE_UPDATE(bezt_array[i].h1, bezt_array[i].h2);
+				}
+			}
+			if (is_cyclic || i != bezt_array_last) {
+				uint i_next = (i != bezt_array_last) ? i + 1 : 0;
+				if (knots[i_next].is_removed) {
+					madd_v3_v3v3fl(bezt_array[i].vec[2], bezt_array[i].vec[1], knots[i].tan[1], knots[i].handles[1]);
+					HANDLE_UPDATE(bezt_array[i].h2, bezt_array[i].h1);
+				}
+			}
+		}
+	}
+
+#undef HANDLE_UPDATE
+
+	MEM_freeN(knots);
+
+	return knots_len_decimated;
+}
+#define SELECT 1
+
+
+void BKE_curve_decimate_nurb(
+        Nurb *nu, const uint resolu,
+        const float error_sq_max, const uint error_target_len)
+{
+	const char flag_test = BEZT_FLAG_TEMP_TAG;
+
+	const uint pntsu_dst = BKE_curve_decimate_bezt_array(
+	        nu->bezt, (uint)nu->pntsu, resolu, (nu->flagu & CU_NURB_CYCLIC) != 0,
+	        SELECT, flag_test,
+	        error_sq_max, error_target_len);
+
+	if (pntsu_dst == (uint)nu->pntsu) {
+		return;
+	}
+
+	BezTriple *bezt_src = nu->bezt;
+	BezTriple *bezt_dst = MEM_mallocN(sizeof(BezTriple) * pntsu_dst, __func__);
+
+	int i_src = 0, i_dst = 0;
+
+	while (i_src < nu->pntsu) {
+		if ((bezt_src[i_src].f2 & flag_test) == 0) {
+			bezt_dst[i_dst] = bezt_src[i_src];
+			i_dst++;
+		}
+		i_src++;
+	}
+
+	MEM_freeN(bezt_src);
+
+	nu->bezt = bezt_dst;
+	nu->pntsu = i_dst;
+}
diff --git a/source/blender/editors/curve/curve_intern.h b/source/blender/editors/curve/curve_intern.h
index 02c76a840f1..bf1e22ae170 100644
--- a/source/blender/editors/curve/curve_intern.h
+++ b/source/blender/editors/curve/curve_intern.h
@@ -109,6 +109,7 @@ void CURVE_OT_radius_set(struct wmOperatorType *ot);
 void CURVE_OT_spline_weight_set(struct wmOperatorType *ot);
 void CURVE_OT_handle_type_set(struct wmOperatorType *ot);
 void CURVE_OT_normals_make_consistent(struct wmOperatorType *ot);
+void CURVE_OT_decimate(struct wmOperatorType *ot);
 void CURVE_OT_shade_smooth(struct wmOperatorType *ot);
 void CURVE_OT_shade_flat(struct wmOperatorType *ot);
 void CURVE_OT_tilt_clear(struct wmOperatorType *ot);
diff --git a/source/blender/editors/curve/curve_ops.c b/source/blender/editors/curve/curve_ops.c
index 5d637b113d8..4dfd4a5c0f0 100644
--- a/source/blender/editors/curve/curve_ops.c
+++ b/source/blender/editors/curve/curve_ops.c
@@ -94,6 +94,7 @@ void ED_operatortypes_curve(void)
 	WM_operatortype_append(CURVE_OT_spline_weight_set);
 	WM_operatortype_append(CURVE_OT_handle_type_set);
 	WM_operatortype_append(CURVE_OT_normals_make_consistent);
+	WM_operatortype_append(CURVE_OT_decimate);
 	WM_operatortype_append(CURVE_OT_shade_smooth);
 	WM_operatortype_append(CURVE_OT_shade_flat);
 	WM_operatortype_append(CURVE_OT_tilt_clear);
diff --git a/source/blender/editors/curve/editcurve.c b/source/blender/editors/curve/editcurve.c
index d14e7eccdf8..ee83f212463 100644
--- a/source/blender/editors/curve/editcurve.c
+++ b/source/blender/editors/curve/editcurve.c
@@ -5905,6 +5905,86 @@ void CURVE_OT_dissolve_verts(wmOperatorType *ot)
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
+static bool nurb_bezt_flag_any(const Nurb *nu, const char flag_test)
+{
+	BezTriple *bezt = nu->bezt;
+	int i;
+
+	for (i = nu->pntsu, bezt = nu->bezt; i--; bezt++) {
+		if (bezt->f2 & flag_test) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static int curve_decimate_exec(bContext *C, wmOperator *op)
+{
+	Object *obedit = CTX_data_edit_object(C);
+	Curve *cu = (Curve *)obedit->data;
+	bool all_supported = true;
+	bool changed = false;
+
+	{
+		const float error_sq_max = FLT_MAX;
+		float ratio = RNA_float_get(op->ptr, "ratio");
+
+		ListBase *editnurb = object_editcurve_get(obedit);
+		Nurb *nu;
+
+		for (nu = editnurb->first; nu; nu = nu->next) {
+			if (nu->type == CU_BEZIER) {
+				if ((nu->pntsu > 2) && nurb_bezt_flag_any(nu, SELECT)) {
+					const int error_target_len = max_ii(2, nu->pntsu * ratio);
+					if (error_target_len != nu->pntsu) {
+						BKE_curve_decimate_nurb(nu, cu->resolu, error_sq_max, error_target_len);
+						changed = true;
+					}
+				}
+			}
+			else {
+				all_supported = false;
+			}
+		}
+	}
+
+	if (all_supported == false) {
+		BKE_report(op->reports, RPT_WARNING, "Only bezier curves are supported");
+	}
+
+	if (changed) {
+		cu->actnu = cu->actvert = CU_ACT_NONE;
+		if (ED_curve_updateAnimPaths(obedit->data)) {
+			WM_event_add_notifier(C, NC_OBJECT | ND_KEYS, obedit);
+		}
+
+		WM_event_add_notifier(C, NC_GEOM | ND_DATA, obedit->data);
+		DAG_id_tag_update(obedit->data, 0);
+	}
+
+	return OPERATOR_FINISHED;
+}
+
+void CURVE_OT_decimate(wmOperatorType *ot)
+{
+	/* identifiers */
+	ot->name = "Decimate Curve";
+	ot->description = "Simplify selected curves";
+	ot->idname = "CURVE_OT_decimate";
+
+	/* api callbacks */
+	ot->exec = curve_decimate_exec;
+	ot->poll = ED_operator_editcurve;
+
+	/* flags */
+	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+	/* properties */
+	RNA_def_float_factor(ot->srna, "ratio", 1.0f, 0.0f, 1.0f, "Ratio", "", 0.0f, 1.0f);
+}
+
+
 /********************** shade smooth/flat operator *********************/
 
 static int shade_smooth_exec(bContext *C, wmOperator *op)
diff --git a/source/blender/makesdna/DNA_curve_types.h b/source/blender/makesdna/DNA_curve_types.h
index 16647e78eff..a25c00915d2 100644
--- a/source/blender/makesdna/DNA_curve_types.h
+++ b/source/blender/makesdna/DNA_curve_types.h
@@ -379,6 +379,12 @@ enum {
 
 /* *************** BEZTRIPLE **************** */
 
+/* BezTriple.f1,2,3 */
+typedef enum eBezTriple_Flag {
+	/* SELECT */
+	BEZT_FLAG_TEMP_TAG = (1 << 1),  /* always clear. */
+} eBezTriple_Flag;
+
 /* h1 h2 (beztriple) */
 typedef enum eBezTriple_Handle {
 	HD_FREE = 0,