Primitives: tangents in the plane primitive.

This turned the primitive from being fully defined at compile time to
being mostly dynamically allocated. Keeping just the positions+normals
case defined at compile time, and splitting the function into two
overloads so the extra code can be DCEd when people call the function
with no flags.

doc/changelog.dox

@@ -196,8 +196,8 @@ See also:
 
 -   @ref Primitives::capsule3DSolid(), @ref Primitives::circle3DSolid(),
     @ref Primitives::coneSolid(), @ref Primitives::cylinderSolid(),
-    @ref Primitives::grid3DSolid() and @ref Primitives::uvSphereSolid() can now
-    have tangents as well
+    @ref Primitives::grid3DSolid(), @ref Primitives::planeSolid() and
+    @ref Primitives::uvSphereSolid() can now have tangents as well
 
 @subsubsection changelog-latest-new-scenegraph SceneGraph library
 

src/Magnum/Primitives/Plane.cpp

@@ -26,7 +26,7 @@
 #include "Plane.h"
 
 #include "Magnum/Mesh.h"
-#include "Magnum/Math/Vector3.h"
+#include "Magnum/Math/Vector4.h"
 #include "Magnum/Trade/MeshData.h"
 
 namespace Magnum { namespace Primitives {
@@ -42,16 +42,6 @@ constexpr struct VertexSolid {
     {{-1.0f, -1.0f, 0.0f}, {0.0f, 0.0f, 1.0f}},
     {{-1.0f,  1.0f, 0.0f}, {0.0f, 0.0f, 1.0f}}
 };
-constexpr struct VertexSolidTextureCoords {
-    Vector3 position;
-    Vector3 normal;
-    Vector2 textureCoords;
-} VerticesSolidTextureCoords[] {
-    {VerticesSolid[0].position, VerticesSolid[0].normal, {1.0f, 0.0f}},
-    {VerticesSolid[1].position, VerticesSolid[1].normal, {1.0f, 1.0f}},
-    {VerticesSolid[2].position, VerticesSolid[2].normal, {0.0f, 0.0f}},
-    {VerticesSolid[3].position, VerticesSolid[3].normal, {0.0f, 1.0f}}
-};
 constexpr Trade::MeshAttributeData AttributesSolid[]{
     Trade::MeshAttributeData{Trade::MeshAttribute::Position,
         Containers::stridedArrayView(VerticesSolid, &VerticesSolid[0].position,
@@ -60,34 +50,92 @@ constexpr Trade::MeshAttributeData AttributesSolid[]{
         Containers::stridedArrayView(VerticesSolid, &VerticesSolid[0].normal,
             Containers::arraySize(VerticesSolid), sizeof(VertexSolid))}
 };
-constexpr Trade::MeshAttributeData AttributesSolidTextureCoords[]{
-    Trade::MeshAttributeData{Trade::MeshAttribute::Position,
-        Containers::stridedArrayView(VerticesSolidTextureCoords,
-            &VerticesSolidTextureCoords[0].position,
-            Containers::arraySize(VerticesSolidTextureCoords), sizeof(VertexSolidTextureCoords))},
-    Trade::MeshAttributeData{Trade::MeshAttribute::Normal,
-        Containers::stridedArrayView(VerticesSolidTextureCoords,
-            &VerticesSolidTextureCoords[0].normal,
-            Containers::arraySize(VerticesSolidTextureCoords), sizeof(VertexSolidTextureCoords))},
-    Trade::MeshAttributeData{Trade::MeshAttribute::TextureCoordinates,
-        Containers::stridedArrayView(VerticesSolidTextureCoords,
-            &VerticesSolidTextureCoords[0].textureCoords,
-            Containers::arraySize(VerticesSolidTextureCoords), sizeof(VertexSolidTextureCoords))},
-};
 
 }
 
-Trade::MeshData planeSolid(const PlaneFlags flags) {
-    if(flags & PlaneFlag::TextureCoordinates)
-        return Trade::MeshData{MeshPrimitive::TriangleStrip,
-            {}, VerticesSolidTextureCoords,
-            Trade::meshAttributeDataNonOwningArray(AttributesSolidTextureCoords)};
-
+Trade::MeshData planeSolid() {
     return Trade::MeshData{MeshPrimitive::TriangleStrip,
         {}, VerticesSolid,
         Trade::meshAttributeDataNonOwningArray(AttributesSolid)};
 }
 
+Trade::MeshData planeSolid(const PlaneFlags flags) {
+    /* Return the compile-time data if nothing extra is requested */
+    if(!flags) return planeSolid();
+
+    /* Calculate attribute count and vertex size */
+    std::size_t stride = sizeof(Vector3) + sizeof(Vector3);
+    std::size_t attributeCount = 2;
+    if(flags & PlaneFlag::Tangents) {
+        stride += sizeof(Vector4);
+        ++attributeCount;
+    }
+    if(flags & PlaneFlag::TextureCoordinates) {
+        stride += sizeof(Vector2);
+        ++attributeCount;
+    }
+
+    /* Set up the layout */
+    Containers::Array<char> vertexData{Containers::NoInit, 4*stride};
+    Containers::Array<Trade::MeshAttributeData> attributeData{attributeCount};
+    std::size_t attributeIndex = 0;
+    std::size_t attributeOffset = 0;
+
+    Containers::StridedArrayView1D<Vector3> positions{vertexData,
+        reinterpret_cast<Vector3*>(vertexData.data() + attributeOffset),
+        4, std::ptrdiff_t(stride)};
+    attributeData[attributeIndex++] = Trade::MeshAttributeData{
+        Trade::MeshAttribute::Position, positions};
+    attributeOffset += sizeof(Vector3);
+
+    Containers::StridedArrayView1D<Vector3> normals{vertexData,
+        reinterpret_cast<Vector3*>(vertexData.data() + sizeof(Vector3)),
+        4, std::ptrdiff_t(stride)};
+    attributeData[attributeIndex++] = Trade::MeshAttributeData{
+        Trade::MeshAttribute::Normal, normals};
+    attributeOffset += sizeof(Vector3);
+
+    Containers::StridedArrayView1D<Vector4> tangents;
+    if(flags & PlaneFlag::Tangents) {
+        tangents = Containers::StridedArrayView1D<Vector4>{vertexData,
+            reinterpret_cast<Vector4*>(vertexData.data() + attributeOffset),
+            4, std::ptrdiff_t(stride)};
+        attributeData[attributeIndex++] = Trade::MeshAttributeData{
+            Trade::MeshAttribute::Tangent, tangents};
+        attributeOffset += sizeof(Vector4);
+    }
+
+    Containers::StridedArrayView1D<Vector2> textureCoordinates;
+    if(flags & PlaneFlag::TextureCoordinates) {
+        textureCoordinates = Containers::StridedArrayView1D<Vector2>{vertexData,
+            reinterpret_cast<Vector2*>(vertexData.data() + attributeOffset),
+            4, std::ptrdiff_t(stride)};
+        attributeData[attributeIndex++] = Trade::MeshAttributeData{
+            Trade::MeshAttribute::TextureCoordinates, textureCoordinates};
+        attributeOffset += sizeof(Vector2);
+    }
+
+    CORRADE_INTERNAL_ASSERT(attributeIndex == attributeCount);
+    CORRADE_INTERNAL_ASSERT(attributeOffset == stride);
+
+    /* Fill the data */
+    for(std::size_t i = 0; i != 4; ++i) {
+        positions[i] = VerticesSolid[i].position;
+        normals[i] = VerticesSolid[i].normal;
+        if(flags & PlaneFlag::Tangents)
+            tangents[i] = {1.0f, 0.0f, 0.0f, 1.0f};
+    }
+    if(flags & PlaneFlag::TextureCoordinates) {
+        textureCoordinates[0] = {1.0f, 0.0f};
+        textureCoordinates[1] = {1.0f, 1.0f};
+        textureCoordinates[2] = {0.0f, 0.0f};
+        textureCoordinates[3] = {0.0f, 1.0f};
+    }
+
+    return Trade::MeshData{MeshPrimitive::TriangleStrip,
+        std::move(vertexData), std::move(attributeData)};
+}
+
 #ifdef MAGNUM_BUILD_DEPRECATED
 CORRADE_IGNORE_DEPRECATED_PUSH
 Trade::MeshData planeSolid(const PlaneTextureCoords textureCoords) {

src/Magnum/Primitives/Plane.h

@@ -45,7 +45,15 @@ namespace Magnum { namespace Primitives {
 */
 enum class PlaneFlag: UnsignedByte {
     /** Generate texture coordinates with origin in bottom left corner */
-    TextureCoordinates = 1 << 0
+    TextureCoordinates = 1 << 0,
+
+    /**
+     * Generate four-component tangents. The last component can be used to
+     * reconstruct a bitangent as described in the documentation of
+     * @ref Trade::MeshAttribute::Tangent.
+     * @m_since_latest
+     */
+    Tangents = 1 << 1
 };
 
 /**
@@ -77,16 +85,22 @@ enum class CORRADE_DEPRECATED_ENUM("use PlaneFlags instead") PlaneTextureCoords:
 @m_since_latest
 
 2x2 plane. Non-indexed @ref MeshPrimitive::TriangleStrip on the XY plane with
-@ref VertexFormat::Vector3 positions and @ref VertexFormat::Vector3 normals in
-positive Z direction. The returned instance references data stored in constant
-memory.
+@ref VertexFormat::Vector3 positions, @ref VertexFormat::Vector3 normals in
+positive Z direction, optional @ref VertexFormat::Vector4 tangents and optional
+@ref VertexFormat::Vector2 texture coordinates. The returned instance may
+reference data stored in constant memory.
 
 @image html primitives-planesolid.png width=256px
 
 @see @ref planeWireframe(), @ref squareSolid(), @ref gradient3D(),
     @ref MeshTools::generateTriangleStripIndices()
 */
-MAGNUM_PRIMITIVES_EXPORT Trade::MeshData planeSolid(PlaneFlags flags = {});
+MAGNUM_PRIMITIVES_EXPORT Trade::MeshData planeSolid(PlaneFlags flags);
+
+/** @overload */
+/* Separate API so apps that don't need texture coordinate / tangents don't
+   need to drag in the extra code needed to allocate & calculate them */
+MAGNUM_PRIMITIVES_EXPORT Trade::MeshData planeSolid();
 
 #ifdef MAGNUM_BUILD_DEPRECATED
 /**

src/Magnum/Primitives/Test/PlaneTest.cpp

@@ -26,7 +26,7 @@
 #include <Corrade/TestSuite/Tester.h>
 
 #include "Magnum/Mesh.h"
-#include "Magnum/Math/Vector3.h"
+#include "Magnum/Math/Vector4.h"
 #include "Magnum/Primitives/Plane.h"
 #include "Magnum/Trade/MeshData.h"
 
@@ -36,42 +36,64 @@ struct PlaneTest: TestSuite::Tester {
     explicit PlaneTest();
 
     void solid();
-    void solidTextured();
     void wireframe();
 };
 
+constexpr struct {
+    const char* name;
+    PlaneFlags flags;
+} SolidData[] {
+    {"", PlaneFlags{}},
+    {"texture coordinates", PlaneFlag::TextureCoordinates},
+    {"tangents", PlaneFlag::Tangents},
+    {"both", PlaneFlag::TextureCoordinates|PlaneFlag::Tangents}
+};
+
 PlaneTest::PlaneTest() {
-    addTests({&PlaneTest::solid,
-              &PlaneTest::solidTextured,
-              &PlaneTest::wireframe});
+    addInstancedTests({&PlaneTest::solid},
+        Containers::arraySize(SolidData));
+
+    addTests({&PlaneTest::wireframe});
 }
 
 void PlaneTest::solid() {
-    Trade::MeshData plane = Primitives::planeSolid();
+    auto&& data = SolidData[testCaseInstanceId()];
+    setTestCaseDescription(data.name);
+
+    Trade::MeshData plane = Primitives::planeSolid(data.flags);
 
     CORRADE_COMPARE(plane.primitive(), MeshPrimitive::TriangleStrip);
     CORRADE_VERIFY(!plane.isIndexed());
     CORRADE_COMPARE(plane.vertexCount(), 4);
-    CORRADE_COMPARE(plane.attributeCount(), 2);
+
     CORRADE_COMPARE(plane.attribute<Vector3>(Trade::MeshAttribute::Position)[3],
         (Vector3{-1.0f, 1.0f, 0.0f}));
-    CORRADE_COMPARE(plane.attribute<Vector3>(Trade::MeshAttribute::Normal)[2],
-        (Vector3{0.0f, 0.0f, 1.0f}));
-}
 
-void PlaneTest::solidTextured() {
-    Trade::MeshData plane = Primitives::planeSolid(Primitives::PlaneFlag::TextureCoordinates);
+    if(data.flags & PlaneFlag::Tangents)
+        CORRADE_COMPARE(plane.attribute<Vector4>(Trade::MeshAttribute::Tangent)[1],
+            (Vector4{1.0f, 0.0f, 0.0f, 1.0f}));
+    else CORRADE_VERIFY(!plane.hasAttribute(Trade::MeshAttribute::Tangent));
 
-    CORRADE_COMPARE(plane.primitive(), MeshPrimitive::TriangleStrip);
-    CORRADE_VERIFY(!plane.isIndexed());
-    CORRADE_COMPARE(plane.vertexCount(), 4);
-    CORRADE_COMPARE(plane.attributeCount(), 3);
-    CORRADE_COMPARE(plane.attribute<Vector3>(Trade::MeshAttribute::Position)[3],
-        (Vector3{-1.0f, 1.0f, 0.0f}));
     CORRADE_COMPARE(plane.attribute<Vector3>(Trade::MeshAttribute::Normal)[2],
         (Vector3{0.0f, 0.0f, 1.0f}));
-    CORRADE_COMPARE(plane.attribute<Vector2>(Trade::MeshAttribute::TextureCoordinates)[1],
-        (Vector2{1.0f, 1.0f}));
+
+    if(data.flags & PlaneFlag::TextureCoordinates)
+        CORRADE_COMPARE(plane.attribute<Vector2>(Trade::MeshAttribute::TextureCoordinates)[1],
+            (Vector2{1.0f, 1.0f}));
+    else CORRADE_VERIFY(!plane.hasAttribute(Trade::MeshAttribute::TextureCoordinates));
+
+    if(data.flags & PlaneFlag::Tangents) {
+        auto tangents = plane.attribute<Vector4>(Trade::MeshAttribute::Tangent);
+        auto normals = plane.attribute<Vector3>(Trade::MeshAttribute::Normal);
+        for(std::size_t i = 0; i != tangents.size(); ++i) {
+            CORRADE_ITERATION(i);
+            CORRADE_ITERATION(tangents[i]);
+            CORRADE_ITERATION(normals[i]);
+            CORRADE_VERIFY(tangents[i].xyz().isNormalized());
+            CORRADE_VERIFY(normals[i].isNormalized());
+            CORRADE_COMPARE(Math::dot(tangents[i].xyz(), normals[i]), 0.0f);
+        }
+    }
 }
 
 void PlaneTest::wireframe() {