assimp/code/Geometry/GeometryUtils.cpp

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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  following disclaimer.

* Redistributions in binary form must reproduce the above
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/

#include "GeometryUtils.h"

#include <assimp/vector3.h>

namespace Assimp {

// ------------------------------------------------------------------------------------------------
ai_real GeometryUtils::heron( ai_real a, ai_real b, ai_real c ) {
    const ai_real s = (a + b + c) / 2;
    const ai_real area = pow((s * ( s - a ) * ( s - b ) * ( s - c ) ), (ai_real)0.5 );
    return area;
}

// ------------------------------------------------------------------------------------------------
ai_real GeometryUtils::distance3D( const aiVector3D &vA, const aiVector3D &vB ) {
    const ai_real lx = ( vB.x - vA.x );
    const ai_real ly = ( vB.y - vA.y );
    const ai_real lz = ( vB.z - vA.z );
    const ai_real a = lx*lx + ly*ly + lz*lz;
    const ai_real d = pow( a, (ai_real)0.5 );

    return d;
}

// ------------------------------------------------------------------------------------------------
ai_real GeometryUtils::calculateAreaOfTriangle( const aiFace& face, aiMesh* mesh ) {
    ai_real area = 0;

    const aiVector3D vA( mesh->mVertices[ face.mIndices[ 0 ] ] );
    const aiVector3D vB( mesh->mVertices[ face.mIndices[ 1 ] ] );
    const aiVector3D vC( mesh->mVertices[ face.mIndices[ 2 ] ] );

    const ai_real a = distance3D( vA, vB );
    const ai_real b = distance3D( vB, vC );
    const ai_real c = distance3D( vC, vA );
    area = heron( a, b, c );

    return area;
}

// ------------------------------------------------------------------------------------------------
// Check whether a ray intersects a plane and find the intersection point
bool GeometryUtils::PlaneIntersect(const aiRay& ray, const aiVector3D& planePos, 
        const aiVector3D& planeNormal, aiVector3D& pos) {
    const ai_real b = planeNormal * (planePos - ray.pos);
    ai_real h = ray.dir * planeNormal;
    if ((h < 10e-5 && h > -10e-5) || (h = b/h) < 0)
        return false;

    pos = ray.pos + (ray.dir * h);
    return true;
}

// ------------------------------------------------------------------------------------------------
void GeometryUtils::normalizeVectorArray(aiVector3D *vectorArrayIn, aiVector3D *vectorArrayOut, 
        size_t numVectors) {
    for (size_t i=0; i<numVectors; ++i) {
		    vectorArrayOut[i] = vectorArrayIn[i].Normalize();
	  }
}

} // namespace Assimp