Curves: Rename "Hair" types, variables, and functions to "Curves"

Based on discussions from T95355 and T94193, the plan is to use
the name "Curves" to describe the data-block container for multiple
curves. Eventually this will replace the existing "Curve" data-block.
However, it will be a while before the curve data-block can be replaced
so in order to distinguish the two curve types in the UI, "Hair Curves"
will be used, but eventually changed back to "Curves".

This patch renames "hair-related" files, functions, types, and variable
names to this convention. A deep rename is preferred to keep code
consistent and to avoid any "hair" terminology from leaking, since the
new data-block is meant for all curve types, not just hair use cases.

The downside of this naming is that the difference between "Curve"
and "Curves" has become important. That was considered during
design discussons and deemed acceptable, especially given the
non-permanent nature of the somewhat common conflict.

Some points of interest:
- All DNA compatibility is lost, just like rBf59767ff9729.
- I renamed `ID_HA` to `ID_CV` so there is no complete mismatch.
- `hair_curves` is used where necessary to distinguish from the
  existing "curves" plural.
- I didn't rename any of the cycles/rendering code function names,
  since that is also used by the old hair particle system.

Differential Revision: https://developer.blender.org/D14007

1 files changed, 108 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_curves_types.h b/source/blender/makesdna/DNA_curves_types.h
new file mode 100644
index 00000000000..c7f31557e48
--- /dev/null
+++ b/source/blender/makesdna/DNA_curves_types.h
@@ -0,0 +1,108 @@
+/*
+ * 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.
+ */
+
+/** \file
+ * \ingroup DNA
+ */
+
+#pragma once
+
+#include "DNA_ID.h"
+#include "DNA_customdata_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * A reusable data structure for geometry consisting of many curves. All control point data is
+ * stored contiguously for better efficiency. Data for each curve is stored as a slice of the
+ * main #point_data array.
+ *
+ * The data structure is meant to be embedded in other data-blocks to allow reusing
+ * curve-processing algorithms for multiple Blender data-block types.
+ */
+typedef struct CurvesGeometry {
+  /**
+   * A runtime pointer to the "position" attribute data.
+   * \note This data is owned by #point_data.
+   */
+  float (*position)[3];
+  /**
+   * A runtime pointer to the "radius" attribute data.
+   * \note This data is owned by #point_data.
+   */
+  float *radius;
+
+  /**
+   * The start index of each curve in the point data. The size of each curve can be calculated by
+   * subtracting the offset from the next offset. That is valid even for the last curve because
+   * this array is allocated with a length one larger than the number of splines.
+   *
+   * \note This is *not* stored in #CustomData because its size is one larger than #curve_data.
+   */
+  int *offsets;
+
+  /**
+   * All attributes stored on control points (#ATTR_DOMAIN_POINT).
+   */
+  CustomData point_data;
+
+  /**
+   * All attributes stored on curves (#ATTR_DOMAIN_CURVE).
+   */
+  CustomData curve_data;
+
+  /**
+   * The total number of control points in all curves.
+   */
+  int point_size;
+  /**
+   * The number of curves in the data-block.
+   */
+  int curve_size;
+} CurvesGeometry;
+
+typedef struct Curves {
+  ID id;
+  /* Animation data (must be immediately after id). */
+  struct AnimData *adt;
+
+  CurvesGeometry geometry;
+
+  int flag;
+  int attributes_active_index;
+
+  /* Materials. */
+  struct Material **mat;
+  short totcol;
+  short _pad2[3];
+
+  /* Draw Cache. */
+  void *batch_cache;
+} Curves;
+
+/* Curves.flag */
+enum {
+  HA_DS_EXPAND = (1 << 0),
+};
+
+/* Only one material supported currently. */
+#define CURVES_MATERIAL_NR 1
+
+#ifdef __cplusplus
+}
+#endif