ImplicitSphere.cpp

#include "ImplicitSphere.h"


ImplicitSphere::ImplicitSphere(MDistance r, float w, MPoint c) 
        : ImplicitFunction(w) { 
        radius = r;
        center = c;
        a = radius.value();
        b = radius.value();
        z = radius.value();
        
}


float ImplicitSphere::implicitValue(MPoint p) {
        //translate the point to the correct position
        p *= m.asMatrix().inverse();
        
        //calculate the implicit function value
        //according to the function of an ellipsoid
        float result = 1 - (std::pow(((p.x-center.x)/a),2))
                                        - (std::pow(((p.y-center.y)/b),2))
                                        - (std::pow(((p.z-center.z)/z),2));
        
        //multiply by the weight to specify the influence of this
        //ImplicitSphere
        return result * weight;
}
                
void ImplicitSphere::applyMatrix(MTransformationMatrix matrix) {
        m = matrix;
}

void ImplicitSphere::applyRadiusWeight(MDistance r, float w) {
        radius = r;
        weight = w;
        a = radius.value();
        b = radius.value();
        z = radius.value();
}

bool ImplicitSphere::testInfluance(MPoint p) {
        //test if the point lies with in the influence radius
        //by a simple sign test.
        if(implicitValue(p)/weight >= 0) {
                return true;
        } else {
                return false;
        }
}
                

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