assimp/code/Common/StandardShapes.cpp

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/** @file   StandardShapes.cpp
 *  @brief  Implementation of the StandardShapes class
 *
 *  The primitive geometry data comes from
 *  http://geometrictools.com/Documentation/PlatonicSolids.pdf.
 */

#include <assimp/StandardShapes.h>
#include <assimp/StringComparison.h>
#include <stddef.h>
#include <assimp/Defines.h>
#include <assimp/mesh.h>

namespace Assimp    {


# define ADD_TRIANGLE(n0,n1,n2) \
    positions.push_back(n0); \
    positions.push_back(n1); \
    positions.push_back(n2);

#   define ADD_PENTAGON(n0,n1,n2,n3,n4) \
    if (polygons) \
    { \
        positions.push_back(n0); \
        positions.push_back(n1); \
        positions.push_back(n2); \
        positions.push_back(n3); \
        positions.push_back(n4); \
    } \
    else \
    { \
        ADD_TRIANGLE(n0, n1, n2) \
        ADD_TRIANGLE(n0, n2, n3) \
        ADD_TRIANGLE(n0, n3, n4) \
    }

#   define ADD_QUAD(n0,n1,n2,n3) \
    if (polygons) \
    { \
        positions.push_back(n0); \
        positions.push_back(n1); \
        positions.push_back(n2); \
        positions.push_back(n3); \
    } \
    else \
    { \
        ADD_TRIANGLE(n0, n1, n2) \
        ADD_TRIANGLE(n0, n2, n3) \
    }


// ------------------------------------------------------------------------------------------------
// Fast subdivision for a mesh whose verts have a magnitude of 1
void Subdivide(std::vector<aiVector3D>& positions)
{
    // assume this to be constant - (fixme: must be 1.0? I think so)
    const ai_real fl1 = positions[0].Length();

    unsigned int origSize = (unsigned int)positions.size();
    for (unsigned int i = 0 ; i < origSize ; i+=3)
    {
        aiVector3D& tv0 = positions[i];
        aiVector3D& tv1 = positions[i+1];
        aiVector3D& tv2 = positions[i+2];

        aiVector3D a = tv0, b = tv1, c = tv2;
        aiVector3D v1 = aiVector3D(a.x+b.x, a.y+b.y, a.z+b.z).Normalize()*fl1;
        aiVector3D v2 = aiVector3D(a.x+c.x, a.y+c.y, a.z+c.z).Normalize()*fl1;
        aiVector3D v3 = aiVector3D(b.x+c.x, b.y+c.y, b.z+c.z).Normalize()*fl1;

        tv0 = v1; tv1 = v3; tv2 = v2; // overwrite the original
        ADD_TRIANGLE(v1, v2, a);
        ADD_TRIANGLE(v2, v3, c);
        ADD_TRIANGLE(v3, v1, b);
    }
}

// ------------------------------------------------------------------------------------------------
// Construct a mesh from given vertex positions
aiMesh* StandardShapes::MakeMesh(const std::vector<aiVector3D>& positions,
    unsigned int numIndices)
{
    if (positions.empty() || !numIndices) return NULL;

    // Determine which kinds of primitives the mesh consists of
    aiMesh* out = new aiMesh();
    switch (numIndices) {
        case 1:
            out->mPrimitiveTypes = aiPrimitiveType_POINT;
            break;
        case 2:
            out->mPrimitiveTypes = aiPrimitiveType_LINE;
            break;
        case 3:
            out->mPrimitiveTypes = aiPrimitiveType_TRIANGLE;
            break;
        default:
            out->mPrimitiveTypes = aiPrimitiveType_POLYGON;
            break;
    };

    out->mNumFaces = (unsigned int)positions.size() / numIndices;
    out->mFaces = new aiFace[out->mNumFaces];
    for (unsigned int i = 0, a = 0; i < out->mNumFaces;++i) {
        aiFace& f = out->mFaces[i];
        f.mNumIndices = numIndices;
        f.mIndices = new unsigned int[numIndices];
        for (unsigned int j = 0; i < numIndices; ++i, ++a) {
            f.mIndices[j] = a;
        }
    }
    out->mNumVertices = (unsigned int)positions.size();
    out->mVertices = new aiVector3D[out->mNumVertices];
    ::memcpy(out->mVertices,&positions[0],out->mNumVertices*sizeof(aiVector3D));

    return out;
}

// ------------------------------------------------------------------------------------------------
// Construct a mesh with a specific shape (callback)
aiMesh* StandardShapes::MakeMesh ( unsigned int (*GenerateFunc)(
    std::vector<aiVector3D>&))
{
    std::vector<aiVector3D> temp;
    unsigned num = (*GenerateFunc)(temp);
    return MakeMesh(temp,num);
}

// ------------------------------------------------------------------------------------------------
// Construct a mesh with a specific shape (callback)
aiMesh* StandardShapes::MakeMesh ( unsigned int (*GenerateFunc)(
    std::vector<aiVector3D>&, bool))
{
    std::vector<aiVector3D> temp;
    unsigned num = (*GenerateFunc)(temp,true);
    return MakeMesh(temp,num);
}

// ------------------------------------------------------------------------------------------------
// Construct a mesh with a specific shape (callback)
aiMesh* StandardShapes::MakeMesh (unsigned int num,  void (*GenerateFunc)(
    unsigned int,std::vector<aiVector3D>&))
{
    std::vector<aiVector3D> temp;
    (*GenerateFunc)(num,temp);
    return MakeMesh(temp,3);
}

// ------------------------------------------------------------------------------------------------
// Build an incosahedron with points.magnitude == 1
unsigned int StandardShapes::MakeIcosahedron(std::vector<aiVector3D>& positions)
{
    positions.reserve(positions.size()+60);

    const ai_real t = ( ai_real( 1.0 )+ ai_real( 2.236067977 ) ) / ai_real( 2.0 );
    const ai_real s = std::sqrt(ai_real(1.0) + t*t);

    const aiVector3D v0  = aiVector3D(t,1.0, 0.0)/s;
    const aiVector3D v1  = aiVector3D(-t,1.0, 0.0)/s;
    const aiVector3D v2  = aiVector3D(t,-1.0, 0.0)/s;
    const aiVector3D v3  = aiVector3D(-t,-1.0, 0.0)/s;
    const aiVector3D v4  = aiVector3D(1.0, 0.0, t)/s;
    const aiVector3D v5  = aiVector3D(1.0, 0.0,-t)/s;
    const aiVector3D v6  = aiVector3D(-1.0, 0.0,t)/s;
    const aiVector3D v7  = aiVector3D(-1.0, 0.0,-t)/s;
    const aiVector3D v8  = aiVector3D(0.0, t, 1.0)/s;
    const aiVector3D v9  = aiVector3D(0.0,-t, 1.0)/s;
    const aiVector3D v10 = aiVector3D(0.0, t,-1.0)/s;
    const aiVector3D v11 = aiVector3D(0.0,-t,-1.0)/s;

    ADD_TRIANGLE(v0,v8,v4);
    ADD_TRIANGLE(v0,v5,v10);
    ADD_TRIANGLE(v2,v4,v9);
    ADD_TRIANGLE(v2,v11,v5);

    ADD_TRIANGLE(v1,v6,v8);
    ADD_TRIANGLE(v1,v10,v7);
    ADD_TRIANGLE(v3,v9,v6);
    ADD_TRIANGLE(v3,v7,v11);

    ADD_TRIANGLE(v0,v10,v8);
    ADD_TRIANGLE(v1,v8,v10);
    ADD_TRIANGLE(v2,v9,v11);
    ADD_TRIANGLE(v3,v11,v9);

    ADD_TRIANGLE(v4,v2,v0);
    ADD_TRIANGLE(v5,v0,v2);
    ADD_TRIANGLE(v6,v1,v3);
    ADD_TRIANGLE(v7,v3,v1);

    ADD_TRIANGLE(v8,v6,v4);
    ADD_TRIANGLE(v9,v4,v6);
    ADD_TRIANGLE(v10,v5,v7);
    ADD_TRIANGLE(v11,v7,v5);
    return 3;
}

// ------------------------------------------------------------------------------------------------
// Build a dodecahedron with points.magnitude == 1
unsigned int StandardShapes::MakeDodecahedron(std::vector<aiVector3D>& positions,
    bool polygons /*= false*/)
{
    positions.reserve(positions.size()+108);

    const ai_real a = ai_real( 1.0 ) / ai_real(1.7320508);
    const ai_real b = std::sqrt(( ai_real( 3.0 )- ai_real( 2.23606797))/ ai_real( 6.0) );
    const ai_real c = std::sqrt(( ai_real( 3.0 )+ ai_real( 2.23606797f))/ ai_real( 6.0) );

    const aiVector3D v0  = aiVector3D(a,a,a);
    const aiVector3D v1  = aiVector3D(a,a,-a);
    const aiVector3D v2  = aiVector3D(a,-a,a);
    const aiVector3D v3  = aiVector3D(a,-a,-a);
    const aiVector3D v4  = aiVector3D(-a,a,a);
    const aiVector3D v5  = aiVector3D(-a,a,-a);
    const aiVector3D v6  = aiVector3D(-a,-a,a);
    const aiVector3D v7  = aiVector3D(-a,-a,-a);
    const aiVector3D v8  = aiVector3D(b,c,0.0);
    const aiVector3D v9  = aiVector3D(-b,c,0.0);
    const aiVector3D v10 = aiVector3D(b,-c,0.0);
    const aiVector3D v11 = aiVector3D(-b,-c,0.0);
    const aiVector3D v12 = aiVector3D(c, 0.0, b);
    const aiVector3D v13 = aiVector3D(c, 0.0, -b);
    const aiVector3D v14 = aiVector3D(-c, 0.0, b);
    const aiVector3D v15 = aiVector3D(-c, 0.0, -b);
    const aiVector3D v16 = aiVector3D(0.0, b, c);
    const aiVector3D v17 = aiVector3D(0.0, -b, c);
    const aiVector3D v18 = aiVector3D(0.0, b, -c);
    const aiVector3D v19 = aiVector3D(0.0, -b, -c);

    ADD_PENTAGON(v0, v8, v9, v4, v16);
    ADD_PENTAGON(v0, v12, v13, v1, v8);
    ADD_PENTAGON(v0, v16, v17, v2, v12);
    ADD_PENTAGON(v8, v1, v18, v5, v9);
    ADD_PENTAGON(v12, v2, v10, v3, v13);
    ADD_PENTAGON(v16, v4, v14, v6, v17);
    ADD_PENTAGON(v9, v5, v15, v14, v4);

    ADD_PENTAGON(v6, v11, v10, v2, v17);
    ADD_PENTAGON(v3, v19, v18, v1, v13);
    ADD_PENTAGON(v7, v15, v5, v18, v19);
    ADD_PENTAGON(v7, v11, v6, v14, v15);
    ADD_PENTAGON(v7, v19, v3, v10, v11);
    return (polygons ? 5 : 3);
}

// ------------------------------------------------------------------------------------------------
// Build an octahedron with points.magnitude == 1
unsigned int StandardShapes::MakeOctahedron(std::vector<aiVector3D>& positions)
{
    positions.reserve(positions.size()+24);

    const aiVector3D v0  = aiVector3D(1.0, 0.0, 0.0) ;
    const aiVector3D v1  = aiVector3D(-1.0, 0.0, 0.0);
    const aiVector3D v2  = aiVector3D(0.0, 1.0, 0.0);
    const aiVector3D v3  = aiVector3D(0.0, -1.0, 0.0);
    const aiVector3D v4  = aiVector3D(0.0, 0.0, 1.0);
    const aiVector3D v5  = aiVector3D(0.0, 0.0, -1.0);

    ADD_TRIANGLE(v4,v0,v2);
    ADD_TRIANGLE(v4,v2,v1);
    ADD_TRIANGLE(v4,v1,v3);
    ADD_TRIANGLE(v4,v3,v0);

    ADD_TRIANGLE(v5,v2,v0);
    ADD_TRIANGLE(v5,v1,v2);
    ADD_TRIANGLE(v5,v3,v1);
    ADD_TRIANGLE(v5,v0,v3);
    return 3;
}

// ------------------------------------------------------------------------------------------------
// Build a tetrahedron with points.magnitude == 1
unsigned int StandardShapes::MakeTetrahedron(std::vector<aiVector3D>& positions)
{
    positions.reserve(positions.size()+9);

    const ai_real invThree = ai_real( 1.0 ) / ai_real( 3.0 );
    const ai_real a = ai_real( 1.41421 ) * invThree;
    const ai_real b = ai_real( 2.4494 ) * invThree;

    const aiVector3D v0  = aiVector3D(0.0,0.0,1.0);
    const aiVector3D v1  = aiVector3D(2*a,0,-invThree );
    const aiVector3D v2  = aiVector3D(-a,b,-invThree );
    const aiVector3D v3  = aiVector3D(-a,-b,-invThree );

    ADD_TRIANGLE(v0,v1,v2);
    ADD_TRIANGLE(v0,v2,v3);
    ADD_TRIANGLE(v0,v3,v1);
    ADD_TRIANGLE(v1,v3,v2);
    return 3;
}

// ------------------------------------------------------------------------------------------------
// Build a hexahedron with points.magnitude == 1
unsigned int StandardShapes::MakeHexahedron(std::vector<aiVector3D>& positions,
    bool polygons /*= false*/)
{
    positions.reserve(positions.size()+36);
    const ai_real length = ai_real(1.0)/ai_real(1.73205080);

    const aiVector3D v0  = aiVector3D(-1.0,-1.0,-1.0)*length;
    const aiVector3D v1  = aiVector3D(1.0,-1.0,-1.0)*length;
    const aiVector3D v2  = aiVector3D(1.0,1.0,-1.0)*length;
    const aiVector3D v3  = aiVector3D(-1.0,1.0,-1.0)*length;
    const aiVector3D v4  = aiVector3D(-1.0,-1.0,1.0)*length;
    const aiVector3D v5  = aiVector3D(1.0,-1.0,1.0)*length;
    const aiVector3D v6  = aiVector3D(1.0,1.0,1.0)*length;
    const aiVector3D v7  = aiVector3D(-1.0,1.0,1.0)*length;

    ADD_QUAD(v0,v3,v2,v1);
    ADD_QUAD(v0,v1,v5,v4);
    ADD_QUAD(v0,v4,v7,v3);
    ADD_QUAD(v6,v5,v1,v2);
    ADD_QUAD(v6,v2,v3,v7);
    ADD_QUAD(v6,v7,v4,v5);
    return (polygons ? 4 : 3);
}

// Cleanup ...
#undef ADD_TRIANGLE
#undef ADD_QUAD
#undef ADD_PENTAGON

// ------------------------------------------------------------------------------------------------
// Create a subdivision sphere
void StandardShapes::MakeSphere(unsigned int    tess,
    std::vector<aiVector3D>& positions)
{
    // Reserve enough storage. Every subdivision
    // splits each triangle in 4, the icosahedron consists of 60 verts
    positions.reserve(positions.size()+60 * integer_pow(4, tess));

    // Construct an icosahedron to start with
    MakeIcosahedron(positions);

    // ... and subdivide it until the requested output
    // tessellation is reached
    for (unsigned int i = 0; i<tess;++i)
        Subdivide(positions);
}

// ------------------------------------------------------------------------------------------------
// Build a cone
void StandardShapes::MakeCone(ai_real height,ai_real radius1,
    ai_real radius2,unsigned int tess,
    std::vector<aiVector3D>& positions,bool bOpen /*= false */)
{
    // Sorry, a cone with less than 3 segments makes ABSOLUTELY NO SENSE
    if (tess < 3 || !height)
        return;

    size_t old = positions.size();

    // No negative radii
    radius1 = std::fabs(radius1);
    radius2 = std::fabs(radius2);

    ai_real halfHeight = height / ai_real(2.0);

    // radius1 is always the smaller one
    if (radius2 > radius1)
    {
        std::swap(radius2,radius1);
        halfHeight = -halfHeight;
    }
    else old = SIZE_MAX;

    // Use a large epsilon to check whether the cone is pointy
    if (radius1 < (radius2-radius1)*10e-3)radius1 = 0.0;

    // We will need 3*2 verts per segment + 3*2 verts per segment
    // if the cone is closed
    const unsigned int mem = tess*6 + (!bOpen ? tess*3 * (radius1 ? 2 : 1) : 0);
    positions.reserve(positions.size () + mem);

    // Now construct all segments
    const ai_real angle_delta = (ai_real)AI_MATH_TWO_PI / tess;
    const ai_real angle_max   = (ai_real)AI_MATH_TWO_PI;

    ai_real s = 1.0; // std::cos(angle == 0);
    ai_real t = 0.0; // std::sin(angle == 0);

    for (ai_real angle = 0.0; angle < angle_max; )
    {
        const aiVector3D v1 = aiVector3D (s * radius1, -halfHeight, t * radius1 );
        const aiVector3D v2 = aiVector3D (s * radius2,  halfHeight, t * radius2 );

        const ai_real next = angle + angle_delta;
        ai_real s2 = std::cos(next);
        ai_real t2 = std::sin(next);

        const aiVector3D v3 = aiVector3D (s2 * radius2,  halfHeight, t2 * radius2 );
        const aiVector3D v4 = aiVector3D (s2 * radius1, -halfHeight, t2 * radius1 );

        positions.push_back(v1);
        positions.push_back(v2);
        positions.push_back(v3);
        positions.push_back(v4);
        positions.push_back(v1);
        positions.push_back(v3);

        if (!bOpen)
        {
            // generate the end 'cap'
            positions.emplace_back(s * radius2,  halfHeight, t * radius2 );
            positions.emplace_back(s2 * radius2,  halfHeight, t2 * radius2 );
            positions.emplace_back(0.0, halfHeight, 0.0);

            if (radius1)
            {
                // generate the other end 'cap'
                positions.emplace_back(s * radius1,  -halfHeight, t * radius1 );
                positions.emplace_back(s2 * radius1,  -halfHeight, t2 * radius1 );
                positions.emplace_back(0.0, -halfHeight, 0.0);
            }
        }

        s = s2;
        t = t2;
        angle = next;
    }

    // Need to flip face order?
    if ( SIZE_MAX != old )  {
        for (size_t p = old; p < positions.size();p += 3) {
            std::swap(positions[p],positions[p+1]);
        }
    }
}

// ------------------------------------------------------------------------------------------------
// Build a circle
void StandardShapes::MakeCircle(ai_real radius, unsigned int tess,
    std::vector<aiVector3D>& positions)
{
    // Sorry, a circle with less than 3 segments makes ABSOLUTELY NO SENSE
    if (tess < 3 || !radius)
        return;

    radius = std::fabs(radius);

    // We will need 3 vertices per segment
    positions.reserve(positions.size()+tess*3);

    const ai_real angle_delta = (ai_real)AI_MATH_TWO_PI / tess;
    const ai_real angle_max   = (ai_real)AI_MATH_TWO_PI;

    ai_real s = 1.0; // std::cos(angle == 0);
    ai_real t = 0.0; // std::sin(angle == 0);

    for (ai_real angle = 0.0; angle < angle_max;  )
    {
        positions.emplace_back(s * radius,0.0,t * radius);

        angle += angle_delta;
        s = std::cos(angle);
        t = std::sin(angle);

        positions.emplace_back(s * radius,0.0,t * radius);
        positions.emplace_back(0.0,0.0,0.0);
    }
}

} // ! Assimp