Curve Decimate: new tool to simplify bezier curves

Access from the curve clean-up menu

1 files changed, 339 insertions, 0 deletions

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;
+}