From 77d7931df2d79eebfcfca1c8db630c5c78338413 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Sun, 19 Jan 2020 15:12:49 +0100
Subject: [PATCH] MeshTools: added a STL-less subdivide().

The subdivideInPlace() alone wasn't convenient enough.
---
 doc/changelog.dox                           |  7 ++++++
 src/Magnum/MeshTools/Subdivide.h            | 25 +++++++++++++++++----
 src/Magnum/MeshTools/Test/SubdivideTest.cpp | 15 +++++++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/doc/changelog.dox b/doc/changelog.dox
index 572de1d3e..b18fac2d5 100644
--- a/doc/changelog.dox
+++ b/doc/changelog.dox
@@ -106,6 +106,11 @@ See also:
 -   Added @ref Math::reflect() and @ref Math::refract() (see
     [mosra/magnum#420](https://github.com/mosra/magnum/pull/420))
 
+@subsubsection changelog-latest-new-meshtools MeshTools library
+
+-   Added @ref MeshTools::subdivideInPlace() for allocation-less mesh
+    subdivision
+
 @subsubsection changelog-latest-new-platform Platform libraries
 
 -   Cursor management using @ref Platform::Sdl2Application::setCursor(),
@@ -205,6 +210,8 @@ See also:
 
 @subsubsection changelog-latest-changes-meshtools MeshTools library
 
+-   Added @ref MeshTools::subdivide() that operates on a (growable)
+    @ref Corrade::Containers::Array instead of a @ref std::vector
 -   Added @ref MeshTools::subdivideInPlace() that operates on a partially
     filled array view instead of a @ref std::vector
 -   Added @ref MeshTools::removeDuplicatesIndexedInPlace() that operates
diff --git a/src/Magnum/MeshTools/Subdivide.h b/src/Magnum/MeshTools/Subdivide.h
index 1796c16f4..72f94b845 100644
--- a/src/Magnum/MeshTools/Subdivide.h
+++ b/src/Magnum/MeshTools/Subdivide.h
@@ -30,6 +30,7 @@
  */
 
 #include <vector>
+#include <Corrade/Containers/GrowableArray.h>
 #include <Corrade/Containers/ArrayViewStl.h>
 #include <Corrade/Containers/StridedArrayView.h>
 #include <Corrade/Utility/Assert.h>
@@ -43,18 +44,34 @@ template<class IndexType, class Vertex, class Interpolator> void subdivideInPlac
 #endif
 
 /**
-@brief Subdivide the mesh
+@brief Subdivide a mesh
 @tparam Vertex          Vertex data type
 @tparam Interpolator    See the @p interpolator function parameter
 @param[in,out] indices  Index array to operate on
 @param[in,out] vertices Vertex array to operate on
 @param interpolator     Functor or function pointer which interpolates
     two adjacent vertices: @cpp Vertex interpolator(Vertex a, Vertex b) @ce
+@m_since_latest
 
-Goes through all triangle faces and subdivides them into four new. Removing
-duplicate vertices in the mesh is up to the user.
+Goes through all triangle faces and subdivides them into four new, enlarging
+the @p indices and @p vertices arrays as appropriate. Removing duplicate
+vertices in the mesh is up to the user.
 @see @ref subdivideInPlace(), @ref removeDuplicatesInPlace()
 */
+template<class IndexType, class Vertex, class Interpolator> void subdivide(Containers::Array<IndexType>& indices, Containers::Array<Vertex>& vertices, Interpolator interpolator) {
+    CORRADE_ASSERT(!(indices.size()%3), "MeshTools::subdivide(): index count is not divisible by 3", );
+
+    arrayResize(vertices, Containers::NoInit, vertices.size() + indices.size());
+    arrayResize(indices, Containers::NoInit, indices.size()*4);
+    subdivideInPlace(Containers::stridedArrayView(indices), Containers::stridedArrayView(vertices), interpolator);
+}
+
+/**
+@brief Subdivide a mesh
+
+Same as @ref subdivide(Containers::Array<IndexType>&, Containers::Array<Vertex>&vertices, Interpolator), only
+working on a @ref std::vector.
+*/
 template<class Vertex, class Interpolator> void subdivide(std::vector<UnsignedInt>& indices, std::vector<Vertex>& vertices, Interpolator interpolator) {
     CORRADE_ASSERT(!(indices.size()%3), "MeshTools::subdivide(): index count is not divisible by 3", );
 
@@ -64,7 +81,7 @@ template<class Vertex, class Interpolator> void subdivide(std::vector<UnsignedIn
 }
 
 /**
-@brief Subdivide the mesh in-place
+@brief Subdivide a mesh in-place
 @tparam Vertex          Vertex data type
 @tparam Interpolator    See the @p interpolator function parameter
 @param[in,out] indices  Index array to operate on
diff --git a/src/Magnum/MeshTools/Test/SubdivideTest.cpp b/src/Magnum/MeshTools/Test/SubdivideTest.cpp
index 390b898f4..865d1299e 100644
--- a/src/Magnum/MeshTools/Test/SubdivideTest.cpp
+++ b/src/Magnum/MeshTools/Test/SubdivideTest.cpp
@@ -37,6 +37,7 @@ struct SubdivideTest: TestSuite::Tester {
     explicit SubdivideTest();
 
     void subdivide();
+    void subdivideStl();
     void subdivideWrongIndexCount();
     template<class T> void subdivideInPlace();
     void subdivideInPlaceWrongIndexCount();
@@ -51,6 +52,7 @@ inline Vector1 interpolator(Vector1 a, Vector1 b) { return (a[0]+b[0])/2; }
 
 SubdivideTest::SubdivideTest() {
     addTests({&SubdivideTest::subdivide,
+              &SubdivideTest::subdivideStl,
               &SubdivideTest::subdivideWrongIndexCount,
               &SubdivideTest::subdivideInPlace<UnsignedByte>,
               &SubdivideTest::subdivideInPlace<UnsignedShort>,
@@ -60,6 +62,19 @@ SubdivideTest::SubdivideTest() {
 }
 
 void SubdivideTest::subdivide() {
+    auto positions = Containers::array<Vector1>({0, 2, 6, 8});
+    auto indices = Containers::array<UnsignedInt>({0, 1, 2, 1, 2, 3});
+    MeshTools::subdivide(indices, positions, interpolator);
+
+    CORRADE_COMPARE_AS(indices, Containers::arrayView<UnsignedInt>({
+        4, 5, 6, 7, 8, 9, 0, 4, 6, 4, 1, 5, 6, 5, 2, 1, 7, 9, 7, 2, 8, 9, 8, 3
+    }), TestSuite::Compare::Container);
+    CORRADE_COMPARE_AS(positions, Containers::arrayView<Vector1>({
+        0, 2, 6, 8, 1, 4, 3, 4, 7, 5
+    }), TestSuite::Compare::Container);
+}
+
+void SubdivideTest::subdivideStl() {
     std::vector<Vector1> positions{0, 2, 6, 8};
     std::vector<UnsignedInt> indices{0, 1, 2, 1, 2, 3};
     MeshTools::subdivide(indices, positions, interpolator);