metaballs.cpp

The metaballs example

// The metaballs example
#include <CoreAPI.h>
//@config: Release
// this is the class with parameters. It is used in UI and for the generating as well. Look the dialogs example.
class Metaballs:public BaseClass {
public:
    Metaballs() {
        numSpheres = 70;
        FigureRadius = 80;
        FigureRadiusVariation = 0.1;
        SpheresRadius = 6;
        SpheresRadiusVariation = 0.5;
    }
    int numSpheres;
    float FigureRadius;
    float FigureRadiusVariation;
    float SpheresRadius;
    float SpheresRadiusVariation;
 
    // this is class registration, look dialogs example
    SERIALIZE() {
        SLIDER(numSpheres, "numSpheres", 1, 1000);
        FSLIDER(FigureRadius, "FigureRadius", 1, 100, 1, false);
        FSLIDER(FigureRadiusVariation, "FigureRadiusVariation", 0, 1, 100, false);
        FSLIDER(SpheresRadius, "SpheresRadius", 1, 100, 1, false);
        FSLIDER(SpheresRadiusVariation, "SpheresRadiusVariation", 0, 1, 100, false);
    }
    // generate random value with variation
    float random(float value, float variation) {
        return value * (1.0f + variation * rand() / 32768.0f);
    }
    // generate the random spheres
    void generate() {
        // add new volume
        auto current = coat::Scene::sculptRoot().addChild("Methaballs:" + coat::str::ToString(numSpheres));
        auto volume = current.Volume();
 
        // turn to voxels
        volume.toVoxels();
        coat::list<coat::vec3> centers;
        coat::list<float> radius;
        for (int i = 0; i < numSpheres; i++) {
            radius.Add(random(SpheresRadius, SpheresRadiusVariation));
            centers.Add(coat::vec3::RandNormal() * random(FigureRadius, FigureRadiusVariation));
        }
        // This function generates the object based on the volumetric formula f(vector) = 0.5
        // It requires also the set of start points.
        volume.makeVoxelFigure(
            [&](coat::vec3 pos) {
                float value = 0;
                for (int i = 0; i < centers.Count(); i++) {
                    // ball radius
                    float r = radius[i];
                    // the square of the distance
                    float d = pos.distanceSq(centers[i]) - radius[i];
                    // the denominator for the formula below
                    float den = d + 16.0f * r - r * r;
                    if (den < 0.01f)den = 0.01f;
                    // the summ
                    value += 32.0f * r / den;
                }
                // the cut threshold
                value -= 2.5f;
                return value;
            }, centers);
    }
};
 
EXPORT
int main() {
    // get to sculpt room
    coat::ui::toRoom("Sculpt");
    // create the generator object
    Metaballs sg;
    coat::dialog dlg;
    // load generator settings if exist
    sg.ReadFromFile("data/Temp/Balls.json");
    if(dlg.ok().cancel().params(&sg).show() == 1) {// ok pressed, buttons start from 1
        // save settings
        sg.WriteToFile("data/Temp/Balls.json");
        // generate the figure
        sg.generate();
    };
    return 0;
}