MeshTools: common helper for remapping MeshAttributeData to new arrays.

So all the locations don't need to be explicitly tested when anything
happens with this -- already way too complex -- MeshAttributeData
constructor.

src/Magnum/MeshTools/CMakeLists.txt

@@ -70,6 +70,7 @@ set(MagnumMeshTools_HEADERS
     visibility.h)
 
 set(MagnumMeshTools_INTERNAL_HEADERS
+    Implementation/remapAttributeData.h
     Implementation/Tipsify.h)
 
 if(MAGNUM_BUILD_DEPRECATED)

src/Magnum/MeshTools/CompressIndices.cpp

@@ -31,6 +31,7 @@
 
 #include "Magnum/Math/FunctionsBatch.h"
 #include "Magnum/MeshTools/Copy.h"
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
 #include "Magnum/Trade/MeshData.h"
 
 #ifdef MAGNUM_BUILD_DEPRECATED
@@ -130,6 +131,7 @@ Trade::MeshData compressIndices(Trade::MeshData&& mesh, MeshIndexType atLeast) {
 
     /* Transfer vertex data as-is, as those don't need any changes. Release if
        possible. */
+    const Containers::ArrayView<const char> originalVertexData = mesh.vertexData();
     Containers::Array<char> vertexData;
     const UnsignedInt vertexCount = mesh.vertexCount();
     if(mesh.vertexDataFlags() & Trade::DataFlag::Owned)
@@ -160,15 +162,12 @@ Trade::MeshData compressIndices(Trade::MeshData&& mesh, MeshIndexType atLeast) {
         result = compressIndicesImplementation<UnsignedByte>(indices, atLeast, offset);
     }
 
-    /* Recreate the attribute array */
+    /* Recreate the attribute array with each attribute being shifted by the
+       offset calculated above */
     const UnsignedInt newVertexCount = vertexCount - offset;
     Containers::Array<Trade::MeshAttributeData> attributeData{mesh.attributeCount()};
     for(UnsignedInt i = 0, max = attributeData.size(); i != max; ++i) {
-        const UnsignedInt stride = mesh.attributeStride(i);
+        attributeData[i] = Implementation::remapAttributeData(mesh.attributeData(i), newVertexCount, originalVertexData, vertexData.exceptPrefix(offset*mesh.attributeStride(i)));
-        attributeData[i] = Trade::MeshAttributeData{mesh.attributeName(i),
-            mesh.attributeFormat(i),
-            Containers::StridedArrayView1D<const void>{vertexData, vertexData.data() + mesh.attributeOffset(i) + offset*stride, newVertexCount, stride},
-            mesh.attributeArraySize(i)};
     }
 
     Trade::MeshIndexData indices{result.second(), result.first()};

src/Magnum/MeshTools/Concatenate.cpp

@@ -29,6 +29,8 @@
 #include <unordered_map>
 #include <Corrade/Utility/Algorithms.h>
 
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
+
 namespace Magnum { namespace MeshTools {
 
 namespace Implementation {
@@ -69,14 +71,8 @@ Trade::MeshData concatenate(Containers::Array<char>&& indexData, const UnsignedI
 
     /* Convert the attributes from offset-only and zero vertex count to
        absolute, referencing the vertex data array */
-    for(Trade::MeshAttributeData& attribute: attributeData) {
+    for(Trade::MeshAttributeData& attribute: attributeData)
-        attribute = Trade::MeshAttributeData{
+        attribute = Implementation::remapAttributeData(attribute, vertexCount, vertexData, vertexData);
-            attribute.name(), attribute.format(),
-            Containers::StridedArrayView1D<void>{vertexData,
-                vertexData + attribute.offset(vertexData),
-                vertexCount, attribute.stride()},
-            attribute.arraySize()};
-    }
 
     /* Only list primitives are supported currently */
     /** @todo delegate to `indexTriangleStrip()` (`duplicate*()`?) etc when

src/Magnum/MeshTools/Copy.cpp

@@ -28,6 +28,7 @@
 #include <Corrade/Utility/Algorithms.h>
 
 #include "Magnum/Trade/MeshData.h"
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
 
 #ifdef MAGNUM_BUILD_DEPRECATED
 #define _MAGNUM_NO_DEPRECATED_MESHTOOLS_REFERENCE
@@ -149,16 +150,8 @@ Trade::MeshData copy(Trade::MeshData&& mesh) {
             if(originalAttribute.isOffsetOnly())
                 attributeData[i] = originalAttribute;
 
-            /* Otherwise it's kinda verbose */
+            /* Otherwise remap it to the new vertex data */
-            else attributeData[i] = Trade::MeshAttributeData{
+            else attributeData[i] = Implementation::remapAttributeData(originalAttribute, vertexCount, originalVertexData, vertexData);
-                originalAttribute.name(),
-                originalAttribute.format(),
-                Containers::StridedArrayView1D<const void>{
-                    vertexData,
-                    vertexData.data() + originalAttribute.offset(originalVertexData),
-                    vertexCount,
-                    originalAttribute.stride()},
-                originalAttribute.arraySize()};
         }
     }
 

src/Magnum/MeshTools/GenerateIndices.cpp

@@ -31,6 +31,7 @@
 
 #include "Magnum/Math/Vector3.h"
 #include "Magnum/MeshTools/Copy.h"
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
 #include "Magnum/Trade/MeshData.h"
 
 namespace Magnum { namespace MeshTools {
@@ -599,6 +600,7 @@ Trade::MeshData generateIndices(Trade::MeshData&& mesh) {
 
     /* Transfer vertex / attribute data as-is, as those don't need any changes.
        Release if possible. */
+    const Containers::ArrayView<const char> originalVertexData = mesh.vertexData();
     Containers::Array<char> vertexData;
     if(mesh.vertexDataFlags() & Trade::DataFlag::Owned)
         vertexData = mesh.releaseVertexData();
@@ -611,12 +613,8 @@ Trade::MeshData generateIndices(Trade::MeshData&& mesh) {
     /** @todo if the vertex data were moved and this array is owned, it
         wouldn't need to be recreated, but the logic is a bit complex */
     Containers::Array<Trade::MeshAttributeData> attributeData{mesh.attributeCount()};
-    for(UnsignedInt i = 0, max = attributeData.size(); i != max; ++i) {
+    for(UnsignedInt i = 0, max = attributeData.size(); i != max; ++i)
-        attributeData[i] = Trade::MeshAttributeData{mesh.attributeName(i),
+        attributeData[i] = Implementation::remapAttributeData(mesh.attributeData(i), vertexCount, originalVertexData, vertexData);
-            mesh.attributeFormat(i),
-            Containers::StridedArrayView1D<const void>{vertexData, vertexData.data() + mesh.attributeOffset(i), vertexCount, mesh.attributeStride(i)},
-            mesh.attributeArraySize(i)};
-    }
 
     /* Generate the index array */
     MeshPrimitive primitive;

src/Magnum/MeshTools/Implementation/remapAttributeData.h

@@ -0,0 +1,53 @@
+#ifndef Magnum_MeshTools_Implementation_remapAttributeData_h
+#define Magnum_MeshTools_Implementation_remapAttributeData_h
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
+                2020, 2021, 2022, 2023 Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "Magnum/Trade/MeshData.h"
+
+namespace Magnum { namespace MeshTools { namespace Implementation {
+
+/* Common helper used by various MeshTools algorithms.
+
+   Remaps MeshAttributeData to be relative to the passed vertexData array,
+   which is assumed to be exactly the same as the original except in different
+   memory location. All properties including array size are kept but
+   offset-only attributes are changed to absolute and attributes with
+   (placeholder) zero vertex count are changed to actual vertex count. */
+inline Trade::MeshAttributeData remapAttributeData(const Trade::MeshAttributeData& attribute, const UnsignedInt vertexCount, const Containers::ArrayView<const char> originalVertexData, Containers::ArrayView<const char> vertexData) {
+    return Trade::MeshAttributeData{
+        attribute.name(),
+        attribute.format(),
+        Containers::StridedArrayView1D<const void>{
+            vertexData,
+            vertexData.data() + attribute.offset(originalVertexData),
+            vertexCount,
+            attribute.stride()},
+        attribute.arraySize()};
+}
+
+}}}
+
+#endif

src/Magnum/MeshTools/Interleave.cpp

@@ -30,6 +30,7 @@
 
 #include "Magnum/Math/Functions.h"
 #include "Magnum/MeshTools/Copy.h"
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
 #include "Magnum/Trade/MeshData.h"
 
 namespace Magnum { namespace MeshTools {
@@ -230,15 +231,11 @@ Trade::MeshData interleavedLayout(Trade::MeshData&& mesh, const UnsignedInt vert
     /* Allocate new data array */
     Containers::Array<char> vertexData{NoInit, attributeData[0].stride()*vertexCount};
 
-    /* Convert the attributes from offset-only and zero vertex count to
+    /* Convert the attributes from all being offset-only and zero vertex count
-       absolute, referencing the above-allocated data array */
+       to absolute, referencing the above-allocated data array */
     for(Trade::MeshAttributeData& attribute: attributeData) {
-        attribute = Trade::MeshAttributeData{
+        CORRADE_INTERNAL_ASSERT(attribute.isOffsetOnly());
-            attribute.name(), attribute.format(),
+        attribute = Implementation::remapAttributeData(attribute, vertexCount, vertexData, vertexData);
-            Containers::StridedArrayView1D<void>{vertexData,
-                vertexData + attribute.offset(vertexData),
-                vertexCount, attribute.stride()},
-            attribute.arraySize()};
     }
 
     return Trade::MeshData{mesh.primitive(), std::move(vertexData), std::move(attributeData)};

src/Magnum/MeshTools/RemoveDuplicates.cpp

@@ -40,6 +40,7 @@
 #include "Magnum/MeshTools/Copy.h"
 #include "Magnum/MeshTools/Duplicate.h"
 #include "Magnum/MeshTools/Interleave.h"
+#include "Magnum/MeshTools/Implementation/remapAttributeData.h"
 #include "Magnum/Trade/MeshData.h"
 
 namespace Magnum { namespace MeshTools {
@@ -456,13 +457,7 @@ Trade::MeshData removeDuplicates(const Trade::MeshData& mesh) {
     /* Route all attributes to the new vertex data */
     Containers::Array<Trade::MeshAttributeData> attributeData{ownedInterleaved.attributeCount()};
     for(UnsignedInt i = 0; i != ownedInterleaved.attributeCount(); ++i)
-        attributeData[i] = Trade::MeshAttributeData{ownedInterleaved.attributeName(i),
+        attributeData[i] = Implementation::remapAttributeData(ownedInterleaved.attributeData(i), uniqueVertexCount, ownedInterleaved.vertexData(), uniqueVertexData);
-            ownedInterleaved.attributeFormat(i),
-            Containers::StridedArrayView1D<void>{uniqueVertexData,
-                uniqueVertexData.data() + ownedInterleaved.attributeOffset(i),
-                uniqueVertexCount,
-                ownedInterleaved.attributeStride(i)},
-            ownedInterleaved.attributeArraySize(i)};
 
     Trade::MeshIndexData indices{indexType, indexData};
     return Trade::MeshData{ownedInterleaved.primitive(),