ch.zweivelo.renderer.simple.shapes.Sphere.java Source code

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Here is the source code for ch.zweivelo.renderer.simple.shapes.Sphere.java

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/*
 * Copyright 2015 Michael Bieri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ch.zweivelo.renderer.simple.shapes;

import ch.zweivelo.renderer.simple.math.Color;
import ch.zweivelo.renderer.simple.math.Ray;
import ch.zweivelo.renderer.simple.math.Solver;
import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;

import java.util.Optional;
import java.util.OptionalDouble;

/**
 * Sphere representation characterized by its location and a radius.
 *
 * @author <a href="mailto:m.bieri@gmx.net">Michael Bieri</a>
 * @version 0.1
 * @since 03.08.2015
 */
public class Sphere extends AbstractShape {

    private final Vector3D center;
    private final double radius;

    public Sphere(final Vector3D center, final double radius) {
        super(Color.RED);
        this.center = center;
        this.radius = radius;
    }

    @Override
    public Optional<Double> calculateIntersectionDistance(final Ray ray) {
        Vector3D dir = ray.getDirection();
        Vector3D tmp = ray.getOrigin().subtract(center);

        OptionalDouble min = Solver.QUADRATIC
                .solve(tmp.dotProduct(tmp) - radius * radius, 2 * dir.dotProduct(tmp), dir.dotProduct(dir)).min();

        if (min.isPresent()) {
            return Optional.of(min.getAsDouble());
        }

        return Optional.empty();
    }

    @Override
    public String toString() {
        return String.format("Sphere{center=%s, radius=%s}", center, radius);
    }
}