Geometry Nodes: Add initial version of mesh primitives

This commit includes nodes to build the following primitives:
 - Cone
 - Cylinder
 - Circle
 - Cube
 - UV Sphere
 - Ico Sphere
 - Line
 - Plane/Grid

In general the inputs are the same as the corresponding operators
in the 3D view.

**Line Primitive**
The line primitive has two modes-- adding vertices between two end
points, or adding vertices each at an offset from the start point.
For the former mode, there is a choice between a vertex count
and a distance between each point.

**Plane Primitive**
This commit includes the "Plane" and "Grid" primitives as one node.
Generally primitives are named after the simpler form of the shape they
create (i.e. "Cone" can make some more complex shapes). Also, generally
you want to tweak the number of subdivisions anyway, so defaulting to
plane is not an inconvenience. And generally having fewer redundant
base primitives is better.

**Future Improvements**
A following patch proposes to improve the speed of the cylinder, cone,
and sphere primitives: D10730. Additional possible future improvements
would be adding subdivisions to the cube node and rings to the cone
and cylinder nodes.

Differential Revision: https://developer.blender.org/D10715

1 files changed, 244 insertions, 0 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc
new file mode 100644
index 00000000000..6d286a9d583
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_mesh_primitive_circle.cc
@@ -0,0 +1,244 @@
+/*
+ * 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 "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BKE_mesh.h"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "node_geometry_util.hh"
+
+static bNodeSocketTemplate geo_node_mesh_primitive_circle_in[] = {
+    {SOCK_INT, N_("Vertices"), 32, 0.0f, 0.0f, 0.0f, 3, 4096},
+    {SOCK_FLOAT, N_("Radius"), 1.0f, 0.0f, 0.0f, 0.0f, 0.0f, FLT_MAX, PROP_DISTANCE},
+    {SOCK_VECTOR, N_("Location"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX, PROP_TRANSLATION},
+    {SOCK_VECTOR, N_("Rotation"), 0.0f, 0.0f, 0.0f, 0.0f, -FLT_MAX, FLT_MAX, PROP_EULER},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_mesh_primitive_circle_out[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+static void geo_node_mesh_primitive_circle_layout(uiLayout *layout,
+                                                  bContext *UNUSED(C),
+                                                  PointerRNA *ptr)
+{
+  uiLayoutSetPropSep(layout, true);
+  uiLayoutSetPropDecorate(layout, false);
+  uiItemR(layout, ptr, "fill_type", 0, nullptr, ICON_NONE);
+}
+
+static void geo_node_mesh_primitive_circle_init(bNodeTree *UNUSED(ntree), bNode *node)
+{
+  NodeGeometryMeshCircle *node_storage = (NodeGeometryMeshCircle *)MEM_callocN(
+      sizeof(NodeGeometryMeshCircle), __func__);
+
+  node_storage->fill_type = GEO_NODE_MESH_CIRCLE_FILL_NONE;
+
+  node->storage = node_storage;
+}
+
+namespace blender::nodes {
+
+static int circle_vert_total(const GeometryNodeMeshCircleFillType fill_type, const int verts_num)
+{
+  switch (fill_type) {
+    case GEO_NODE_MESH_CIRCLE_FILL_NONE:
+    case GEO_NODE_MESH_CIRCLE_FILL_NGON:
+      return verts_num;
+    case GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN:
+      return verts_num + 1;
+  }
+  BLI_assert(false);
+  return 0;
+}
+
+static int circle_edge_total(const GeometryNodeMeshCircleFillType fill_type, const int verts_num)
+{
+  switch (fill_type) {
+    case GEO_NODE_MESH_CIRCLE_FILL_NONE:
+    case GEO_NODE_MESH_CIRCLE_FILL_NGON:
+      return verts_num;
+    case GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN:
+      return verts_num * 2;
+  }
+  BLI_assert(false);
+  return 0;
+}
+
+static int circle_corner_total(const GeometryNodeMeshCircleFillType fill_type, const int verts_num)
+{
+  switch (fill_type) {
+    case GEO_NODE_MESH_CIRCLE_FILL_NONE:
+      return 0;
+    case GEO_NODE_MESH_CIRCLE_FILL_NGON:
+      return verts_num;
+    case GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN:
+      return verts_num * 3;
+  }
+  BLI_assert(false);
+  return 0;
+}
+
+static int circle_face_total(const GeometryNodeMeshCircleFillType fill_type, const int verts_num)
+{
+  switch (fill_type) {
+    case GEO_NODE_MESH_CIRCLE_FILL_NONE:
+      return 0;
+    case GEO_NODE_MESH_CIRCLE_FILL_NGON:
+      return 1;
+    case GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN:
+      return verts_num;
+  }
+  BLI_assert(false);
+  return 0;
+}
+
+static Mesh *create_circle_mesh(const float radius,
+                                const int verts_num,
+                                const GeometryNodeMeshCircleFillType fill_type)
+{
+  Mesh *mesh = BKE_mesh_new_nomain(circle_vert_total(fill_type, verts_num),
+                                   circle_edge_total(fill_type, verts_num),
+                                   0,
+                                   circle_corner_total(fill_type, verts_num),
+                                   circle_face_total(fill_type, verts_num));
+  MutableSpan<MVert> verts{mesh->mvert, mesh->totvert};
+  MutableSpan<MLoop> loops{mesh->mloop, mesh->totloop};
+  MutableSpan<MEdge> edges{mesh->medge, mesh->totedge};
+  MutableSpan<MPoly> polys{mesh->mpoly, mesh->totpoly};
+
+  float angle = 0.0f;
+  const float angle_delta = 2.0f * M_PI / static_cast<float>(verts_num);
+  for (MVert &vert : verts) {
+    copy_v3_v3(vert.co, float3(std::cos(angle) * radius, std::sin(angle) * radius, 0.0f));
+    angle += angle_delta;
+  }
+  if (fill_type == GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN) {
+    copy_v3_v3(verts.last().co, float3(0));
+  }
+
+  /* Point all vertex normals in the up direction. */
+  const short up_normal[3] = {0, 0, SHRT_MAX};
+  for (MVert &vert : verts) {
+    copy_v3_v3_short(vert.no, up_normal);
+  }
+
+  /* Create outer edges. */
+  for (const int i : IndexRange(verts_num)) {
+    MEdge &edge = edges[i];
+    edge.v1 = i;
+    edge.v2 = (i + 1) % verts_num;
+  }
+
+  /* Set loose edge flags. */
+  if (fill_type == GEO_NODE_MESH_CIRCLE_FILL_NONE) {
+    for (const int i : IndexRange(verts_num)) {
+      MEdge &edge = edges[i];
+      edge.flag |= ME_LOOSEEDGE;
+    }
+  }
+
+  /* Create triangle fan edges. */
+  if (fill_type == GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN) {
+    for (const int i : IndexRange(verts_num)) {
+      MEdge &edge = edges[verts_num + i];
+      edge.v1 = verts_num;
+      edge.v2 = i;
+    }
+  }
+
+  /* Create corners and faces. */
+  if (fill_type == GEO_NODE_MESH_CIRCLE_FILL_NGON) {
+    MPoly &poly = polys[0];
+    poly.loopstart = 0;
+    poly.totloop = loops.size();
+
+    for (const int i : IndexRange(verts_num)) {
+      MLoop &loop = loops[i];
+      loop.e = i;
+      loop.v = i;
+    }
+  }
+  else if (fill_type == GEO_NODE_MESH_CIRCLE_FILL_TRIANGLE_FAN) {
+    for (const int i : IndexRange(verts_num)) {
+      MPoly &poly = polys[i];
+      poly.loopstart = 3 * i;
+      poly.totloop = 3;
+
+      MLoop &loop_a = loops[3 * i];
+      loop_a.e = i;
+      loop_a.v = i;
+      MLoop &loop_b = loops[3 * i + 1];
+      loop_b.e = verts_num + ((i + 1) % verts_num);
+      loop_b.v = (i + 1) % verts_num;
+      MLoop &loop_c = loops[3 * i + 2];
+      loop_c.e = verts_num + i;
+      loop_c.v = verts_num;
+    }
+  }
+
+  return mesh;
+}
+
+static void geo_node_mesh_primitive_circle_exec(GeoNodeExecParams params)
+{
+  const bNode &node = params.node();
+  const NodeGeometryMeshCircle &storage = *(const NodeGeometryMeshCircle *)node.storage;
+
+  const GeometryNodeMeshCircleFillType fill_type = (const GeometryNodeMeshCircleFillType)
+                                                       storage.fill_type;
+
+  const int verts_num = params.extract_input<int>("Vertices");
+  if (verts_num < 3) {
+    params.set_output("Geometry", GeometrySet());
+    return;
+  }
+
+  const float radius = params.extract_input<float>("Radius");
+  const float3 location = params.extract_input<float3>("Location");
+  const float3 rotation = params.extract_input<float3>("Rotation");
+
+  Mesh *mesh = create_circle_mesh(radius, verts_num, fill_type);
+
+  BLI_assert(BKE_mesh_is_valid(mesh));
+
+  transform_mesh(mesh, location, rotation, float3(1));
+
+  params.set_output("Geometry", GeometrySet::create_with_mesh(mesh));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_mesh_primitive_circle()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_MESH_PRIMITIVE_CIRCLE, "Circle", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(
+      &ntype, geo_node_mesh_primitive_circle_in, geo_node_mesh_primitive_circle_out);
+  node_type_init(&ntype, geo_node_mesh_primitive_circle_init);
+  node_type_storage(
+      &ntype, "NodeGeometryMeshCircle", node_free_standard_storage, node_copy_standard_storage);
+  ntype.geometry_node_execute = blender::nodes::geo_node_mesh_primitive_circle_exec;
+  ntype.draw_buttons = geo_node_mesh_primitive_circle_layout;
+  nodeRegisterType(&ntype);
+}