Add Chromium-only Blender WebEngine parity work

blender-5.2.0/intern/cycles/scene/mesh_subdivision.cpp

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+/* SPDX-FileCopyrightText: 2011-2025 Blender Foundation
+ *
+ * SPDX-License-Identifier: Apache-2.0 */
+
+#include "scene/attribute.h"
+#include "scene/mesh.h"
+
+#include "subd/interpolation.h"
+#include "subd/osd.h"
+#include "subd/patch.h"
+#include "subd/split.h"
+
+#include "util/algorithm.h"
+#include "util/vector.h"
+
+CCL_NAMESPACE_BEGIN
+
+void Mesh::tessellate(SubdParams &params)
+{
+  /* reset the number of subdivision vertices, in case the Mesh was not cleared
+   * between calls or data updates */
+  num_subd_added_verts = 0;
+  const int num_faces = get_num_subd_faces();
+
+  /* If there are no faces there is nothing to subdivide, and the required
+   * subd position attribute may not exist. */
+  if (num_faces == 0) {
+    return;
+  }
+
+#ifdef WITH_OPENSUBDIV
+  OsdMesh osd_mesh(*this);
+  OsdData osd_data;
+
+  if (subdivision_type == SUBDIVISION_CATMULL_CLARK) {
+    if (get_num_subd_faces()) {
+      osd_data.build(osd_mesh);
+    }
+  }
+  else
+#endif
+  {
+    /* force linear subdivision if OpenSubdiv is unavailable to avoid
+     * falling into catmull-clark code paths by accident
+     */
+    subdivision_type = SUBDIVISION_LINEAR;
+  }
+
+  /* count patches */
+  int num_patches = 0;
+  for (int f = 0; f < num_faces; f++) {
+    SubdFace face = get_subd_face(f);
+
+    if (face.is_quad()) {
+      num_patches++;
+    }
+    else {
+      num_patches += face.num_corners;
+    }
+  }
+
+  /* build patches from faces */
+#ifdef WITH_OPENSUBDIV
+  if (subdivision_type == SUBDIVISION_CATMULL_CLARK) {
+    vector<OsdPatch> osd_patches(num_patches, OsdPatch(osd_data));
+    OsdPatch *patch = osd_patches.data();
+
+    for (int f = 0; f < num_faces; f++) {
+      SubdFace face = get_subd_face(f);
+
+      if (face.is_quad()) {
+        patch->patch_index = face.ptex_offset;
+        patch->from_ngon = false;
+        patch->shader = face.shader;
+        patch->smooth = face.smooth;
+        patch++;
+      }
+      else {
+        for (int corner = 0; corner < face.num_corners; corner++) {
+          patch->patch_index = face.ptex_offset + corner;
+          patch->from_ngon = true;
+          patch->shader = face.shader;
+          patch->smooth = face.smooth;
+          patch++;
+        }
+      }
+    }
+
+    /* Split patches. */
+    DiagSplit split(params);
+    split.split_patches(osd_patches.data(), sizeof(OsdPatch));
+
+    /* Setup interpolation. */
+    SubdAttributeInterpolation interpolation(*this, osd_mesh, osd_data);
+
+    /* Dice patches. */
+    EdgeDice dice(params, split.get_num_verts(), split.get_num_triangles(), interpolation);
+    dice.dice(split);
+  }
+  else
+#endif
+  {
+    vector<LinearQuadPatch> linear_patches(num_patches);
+    LinearQuadPatch *patch = linear_patches.data();
+    const Attribute *subd_attr_P = subd_attributes.find(ATTR_STD_POSITION);
+    const packed_float3 *verts = subd_attr_P->data<packed_float3>();
+
+    for (int f = 0; f < num_faces; f++) {
+      SubdFace face = get_subd_face(f);
+
+      if (face.is_quad()) {
+        /* Simple quad case. */
+        float3 *hull = patch->hull;
+
+        patch->patch_index = face.ptex_offset;
+        patch->from_ngon = false;
+
+        hull[0] = verts[subd_face_corners[face.start_corner + 0]];
+        hull[1] = verts[subd_face_corners[face.start_corner + 1]];
+        hull[2] = verts[subd_face_corners[face.start_corner + 3]];
+        hull[3] = verts[subd_face_corners[face.start_corner + 2]];
+
+        patch->shader = face.shader;
+        patch->smooth = face.smooth;
+        patch++;
+      }
+      else {
+        /* N-gon split into N quads. */
+        float3 center_vert = zero_float3();
+
+        const float inv_num_corners = 1.0f / float(face.num_corners);
+        for (int corner = 0; corner < face.num_corners; corner++) {
+          center_vert += verts[subd_face_corners[face.start_corner + corner]] * inv_num_corners;
+        }
+
+        for (int corner = 0; corner < face.num_corners; corner++) {
+          float3 *hull = patch->hull;
+
+          patch->patch_index = face.ptex_offset + corner;
+          patch->from_ngon = true;
+
+          patch->shader = face.shader;
+          patch->smooth = face.smooth;
+
+          const int v0 = subd_face_corners[face.start_corner + mod(corner + 0, face.num_corners)];
+          const int v1 = subd_face_corners[face.start_corner + mod(corner + 1, face.num_corners)];
+          const int v3 = subd_face_corners[face.start_corner +
+                                           mod(corner + face.num_corners - 1, face.num_corners)];
+
+          hull[0] = verts[v0];
+          hull[1] = 0.5f * (verts[v0] + verts[v1]);
+          hull[2] = 0.5f * (verts[v3] + verts[v0]);
+          hull[3] = center_vert;
+
+          patch++;
+        }
+      }
+    }
+
+    /* Split patches. */
+    DiagSplit split(params);
+    split.split_patches(linear_patches.data(), sizeof(LinearQuadPatch));
+
+    /* Setup interpolation. */
+#ifdef WITH_OPENSUBDIV
+    SubdAttributeInterpolation interpolation(*this, osd_mesh, osd_data);
+#else
+    SubdAttributeInterpolation interpolation(*this);
+#endif
+
+    /* Dice patches. */
+    EdgeDice dice(params, split.get_num_verts(), split.get_num_triangles(), interpolation);
+    dice.dice(split);
+  }
+
+  // TODO: Free subd base data? Or will this break interactive updates?
+}
+
+CCL_NAMESPACE_END