io.rtron.math.processing.triangulation.TriangulationAlgorithm.kt Maven / Gradle / Ivy

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/*
 * Copyright 2019-2022 Chair of Geoinformatics, Technical University of Munich
 *
 * 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 io.rtron.math.processing.triangulation

import com.github.kittinunf.result.Result
import io.rtron.math.geometry.euclidean.threed.point.Vector3D
import io.rtron.math.geometry.euclidean.threed.surface.Polygon3D
import io.rtron.std.handleFailure

/**
 * Abstract class for a triangulation algorithm in 3D.
 * See the wikipedia article of [polygon triangulation](https://en.wikipedia.org/wiki/Polygon_triangulation).
 */
abstract class TriangulationAlgorithm {

    /**
     * Performs the triangulation operation and checks whether all input vertices are still represented
     * after triangulation.
     *
     * @param vertices list of vertices representing the outline to be triangulated
     * @return list of triangulated [Polygon3D]
     */
    fun triangulateChecked(vertices: List, tolerance: Double): Result, Exception> {

        val triangles = triangulate(vertices, tolerance).handleFailure { return it }

        val newVertices = triangles.flatMap { it.vertices }
        if (newVertices.any { it !in vertices })
            return Result.error(RuntimeException("Triangulation algorithm produces different vertices."))

        return Result.success(triangles)
    }

    /**
     * Triangulation algorithm implemented by concrete classes.
     *
     * @param vertices list of vertices representing the outline to be triangulated
     * @return list of triangulated [Polygon3D]
     */
    internal abstract fun triangulate(vertices: List, tolerance: Double): Result, Exception>
}