Geometry Nodes: Curve Primitive Circle

This node has two modes: the first mode computes a circle from three
locations and a resolution. The second takes radius and resolution.
The first mode also outputs the center of the computed circle as
a vector.

Differential Revision: https://developer.blender.org/D11650

1 files changed, 227 insertions, 0 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_curve_primitive_circle.cc b/source/blender/nodes/geometry/nodes/node_geo_curve_primitive_circle.cc
new file mode 100644
index 00000000000..93ca5a1a677
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_curve_primitive_circle.cc
@@ -0,0 +1,227 @@
+/*
+ * 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.
+ */
+
+#include "BKE_spline.hh"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "node_geometry_util.hh"
+
+static bNodeSocketTemplate geo_node_curve_primitive_circle_in[] = {
+    {SOCK_INT, N_("Resolution"), 32.0f, 0.0f, 0.0f, 0.0f, 3.0f, 512.0f},
+    {SOCK_VECTOR, N_("Point 1"), -1.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX, PROP_TRANSLATION},
+    {SOCK_VECTOR, N_("Point 2"), 0.0f, 1.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX, PROP_TRANSLATION},
+    {SOCK_VECTOR, N_("Point 3"), 1.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX, PROP_TRANSLATION},
+    {SOCK_FLOAT, N_("Radius"), 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_curve_primitive_circle_out[] = {
+    {SOCK_GEOMETRY, N_("Curve")},
+    {SOCK_VECTOR, N_("Center")},
+    {-1, ""},
+};
+
+static void geo_node_curve_primitive_circle_layout(uiLayout *layout,
+                                                   bContext *UNUSED(C),
+                                                   PointerRNA *ptr)
+{
+  uiItemR(layout, ptr, "mode", UI_ITEM_R_EXPAND, nullptr, ICON_NONE);
+}
+
+namespace blender::nodes {
+
+static void geo_node_curve_primitive_circle_init(bNodeTree *UNUSED(tree), bNode *node)
+{
+  NodeGeometryCurvePrimitiveCircle *data = (NodeGeometryCurvePrimitiveCircle *)MEM_callocN(
+      sizeof(NodeGeometryCurvePrimitiveCircle), __func__);
+
+  data->mode = GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_RADIUS;
+  node->storage = data;
+}
+
+static void geo_node_curve_primitive_circle_update(bNodeTree *UNUSED(ntree), bNode *node)
+{
+  const NodeGeometryCurvePrimitiveCircle *node_storage = (NodeGeometryCurvePrimitiveCircle *)
+                                                             node->storage;
+  const GeometryNodeCurvePrimitiveCircleMode mode = (const GeometryNodeCurvePrimitiveCircleMode)
+                                                        node_storage->mode;
+
+  bNodeSocket *start_socket = ((bNodeSocket *)node->inputs.first)->next;
+  bNodeSocket *middle_socket = start_socket->next;
+  bNodeSocket *end_socket = middle_socket->next;
+  bNodeSocket *radius_socket = end_socket->next;
+
+  bNodeSocket *center_socket = ((bNodeSocket *)node->outputs.first)->next;
+
+  nodeSetSocketAvailability(start_socket, mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS);
+  nodeSetSocketAvailability(middle_socket, mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS);
+  nodeSetSocketAvailability(end_socket, mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS);
+  nodeSetSocketAvailability(center_socket, mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS);
+  nodeSetSocketAvailability(radius_socket, mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_RADIUS);
+}
+
+static bool colinear_f3_f3_f3(const float3 p1, const float3 p2, const float3 p3)
+{
+  const float3 a = (p2 - p1).normalized();
+  const float3 b = (p3 - p1).normalized();
+  return (a == b || a == b * -1.0f);
+}
+
+static std::unique_ptr<CurveEval> create_point_circle_curve(
+    const float3 p1, const float3 p2, const float3 p3, const int resolution, float center_out[3])
+{
+  if (colinear_f3_f3_f3(p1, p2, p3)) {
+    return nullptr;
+  }
+
+  std::unique_ptr<CurveEval> curve = std::make_unique<CurveEval>();
+  std::unique_ptr<PolySpline> spline = std::make_unique<PolySpline>();
+
+  spline->resize(resolution);
+  MutableSpan<float3> positions = spline->positions();
+
+  float3 center;
+  /* Midpoints of P1->P2 and P2->P3. */
+  const float3 q1 = float3::interpolate(p1, p2, 0.5f);
+  const float3 q2 = float3::interpolate(p2, p3, 0.5f);
+
+  /* Normal Vectors of P1->P2 and P2->P3*/
+  const float3 v1 = (p2 - p1).normalized();
+  const float3 v2 = (p3 - p2).normalized();
+
+  /*Normal of plane of main 2 segments P1->P2 and P2->P3. */
+  const float3 v3 = float3::cross(v1, v2).normalized();
+
+  /*Normal of plane of first perpendicular bisector and P1->P2. */
+  const float3 v4 = float3::cross(v3, v1).normalized();
+
+  /* Determine Centerpoint from the intersection of 3 planes. */
+  float plane_1[4], plane_2[4], plane_3[4];
+  plane_from_point_normal_v3(plane_1, q1, v3);
+  plane_from_point_normal_v3(plane_2, q1, v1);
+  plane_from_point_normal_v3(plane_3, q2, v2);
+
+  /* If the 3 planes do not intersect at one point, just return empty geometry. */
+  if (!isect_plane_plane_plane_v3(plane_1, plane_2, plane_3, center)) {
+    return nullptr;
+  }
+
+  /* Get the radius from the centerpoint to p1. */
+  const float r = float3::distance(p1, center);
+  const float theta_step = ((2 * M_PI) / (float)resolution);
+  for (const int i : IndexRange(resolution)) {
+
+    /* Formula for a circle around a point and 2 unit vectors perp. to each other and the axis of
+     * the cirlce from
+     * https://math.stackexchange.com/questions/73237/parametric-equation-of-a-circle-in-3d-space
+     */
+
+    const float theta = theta_step * i;
+    positions[i] = center + r * cos(theta) * v1 + r * sin(theta) * v4;
+  }
+
+  spline->radii().fill(1.0f);
+  spline->tilts().fill(0.0f);
+  spline->set_cyclic(true);
+  curve->add_spline(std::move(spline));
+  curve->attributes.reallocate(curve->splines().size());
+
+  copy_v3_v3(center_out, center);
+  return curve;
+}
+
+static std::unique_ptr<CurveEval> create_radius_circle_curve(const int resolution,
+                                                             const float radius)
+{
+  std::unique_ptr<CurveEval> curve = std::make_unique<CurveEval>();
+  std::unique_ptr<PolySpline> spline = std::make_unique<PolySpline>();
+
+  spline->resize(resolution);
+  MutableSpan<float3> positions = spline->positions();
+
+  const float theta_step = (2.0f * M_PI) / float(resolution);
+  for (int i : IndexRange(resolution)) {
+    const float theta = theta_step * i;
+    const float x = radius * cos(theta);
+    const float y = radius * sin(theta);
+    positions[i] = float3(x, y, 0.0f);
+  }
+  spline->radii().fill(1.0f);
+  spline->tilts().fill(0.0f);
+  spline->set_cyclic(true);
+  curve->add_spline(std::move(spline));
+  curve->attributes.reallocate(curve->splines().size());
+  return curve;
+}
+
+static void geo_node_curve_primitive_circle_exec(GeoNodeExecParams params)
+{
+  const NodeGeometryCurvePrimitiveCircle *node_storage =
+      (NodeGeometryCurvePrimitiveCircle *)params.node().storage;
+
+  const GeometryNodeCurvePrimitiveCircleMode mode = (GeometryNodeCurvePrimitiveCircleMode)
+                                                        node_storage->mode;
+
+  std::unique_ptr<CurveEval> curve;
+  if (mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS) {
+    float center_point[3];
+    curve = create_point_circle_curve(params.extract_input<float3>("Point 1"),
+                                      params.extract_input<float3>("Point 2"),
+                                      params.extract_input<float3>("Point 3"),
+                                      std::max(params.extract_input<int>("Resolution"), 3),
+                                      center_point);
+    if (curve) {
+      params.set_output("Center", float3(center_point));
+    }
+    else {
+      params.set_output("Center", float3(0, 0, 0));
+    }
+  }
+  else if (mode == GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_RADIUS) {
+    curve = create_radius_circle_curve(std::max(params.extract_input<int>("Resolution"), 3),
+                                       params.extract_input<float>("Radius"));
+  }
+
+  if (curve) {
+    params.set_output("Curve", GeometrySet::create_with_curve(curve.release()));
+  }
+  else {
+    params.set_output("Curve", GeometrySet());
+  }
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_curve_primitive_circle()
+{
+  static bNodeType ntype;
+  geo_node_type_base(&ntype, GEO_NODE_CURVE_PRIMITIVE_CIRCLE, "Circle", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(
+      &ntype, geo_node_curve_primitive_circle_in, geo_node_curve_primitive_circle_out);
+
+  node_type_init(&ntype, blender::nodes::geo_node_curve_primitive_circle_init);
+  node_type_update(&ntype, blender::nodes::geo_node_curve_primitive_circle_update);
+  node_type_storage(&ntype,
+                    "NodeGeometryCurvePrimitiveCircle",
+                    node_free_standard_storage,
+                    node_copy_standard_storage);
+
+  ntype.geometry_node_execute = blender::nodes::geo_node_curve_primitive_circle_exec;
+  ntype.draw_buttons = geo_node_curve_primitive_circle_layout;
+  nodeRegisterType(&ntype);
+}
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