/*
 * The MIT License
 *
 * Copyright (c) 2015-2021 Kai Burjack
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.jozufozu.flywheel.repack.joml;

/**
 * Useful geometry methods.
 *
 * @author Kai Burjack
 * @author Richard Greenlees
 */
public class GeometryUtils {

    /**
     * Compute two arbitrary vectors perpendicular to the given normalized vector <code>(x, y, z)</code>, and store them in <code>dest1</code> and <code>dest2</code>,
     * respectively.
     * <p>
     * The computed vectors will themselves be perpendicular to each another and normalized. So the tree vectors <code>(x, y, z)</code>, <code>dest1</code> and
     * <code>dest2</code> form an orthonormal basis.
     *
     * @param x
     *            the x coordinate of the normalized input vector
     * @param y
     *            the y coordinate of the normalized input vector
     * @param z
     *            the z coordinate of the normalized input vector
     * @param dest1
     *            will hold the first perpendicular vector
     * @param dest2
     *            will hold the second perpendicular vector
     */
    public static void perpendicular(float x, float y, float z, Vector3f dest1, Vector3f dest2) {
        float magX = z * z + y * y;
        float magY = z * z + x * x;
        float magZ = y * y + x * x;
        float mag;
        if (magX > magY && magX > magZ) {
            dest1.x = 0;
            dest1.y = z;
            dest1.z = -y;
            mag = magX;
        } else if (magY > magZ) {
            dest1.x = -z;
            dest1.y = 0;
            dest1.z = x;
            mag = magY;
        } else {
            dest1.x = y;
            dest1.y = -x;
            dest1.z = 0;
            mag = magZ;
        }
        float len = Math.invsqrt(mag);
        dest1.x *= len;
        dest1.y *= len;
        dest1.z *= len;
        dest2.x = y * dest1.z - z * dest1.y;
        dest2.y = z * dest1.x - x * dest1.z;
        dest2.z = x * dest1.y - y * dest1.x;
    }

    /**
     * Compute two arbitrary vectors perpendicular to the given normalized vector <code>v</code>, and store them in <code>dest1</code> and <code>dest2</code>,
     * respectively.
     * <p>
     * The computed vectors will themselves be perpendicular to each another and normalized. So the tree vectors <code>v</code>, <code>dest1</code> and
     * <code>dest2</code> form an orthonormal basis.
     *
     * @param v
     *            the {@link Vector3f#normalize() normalized} input vector
     * @param dest1
     *            will hold the first perpendicular vector
     * @param dest2
     *            will hold the second perpendicular vector
     */
    public static void perpendicular(Vector3fc v, Vector3f dest1, Vector3f dest2) {
        perpendicular(v.x(), v.y(), v.z(), dest1, dest2);
    }

    /**
     * Calculate the normal of a surface defined by points <code>v1</code>, <code>v2</code> and <code>v3</code> and store it in <code>dest</code>.
     *
     * @param v0
     *            the first position
     * @param v1
     *            the second position
     * @param v2
     *            the third position
     * @param dest
     *            will hold the result
     */
    public static void normal(Vector3fc v0, Vector3fc v1, Vector3fc v2, Vector3f dest) {
        normal(v0.x(), v0.y(), v0.z(), v1.x(), v1.y(), v1.z(), v2.x(), v2.y(), v2.z(), dest);
    }

    /**
     * Calculate the normal of a surface defined by points <code>(v1X, v1Y, v1Z)</code>, <code>(v2X, v2Y, v2Z)</code> and <code>(v3X, v3Y, v3Z)</code>
     * and store it in <code>dest</code>.
     *
     * @param v0X
     *            the x coordinate of the first position
     * @param v0Y
     *            the y coordinate of the first position
     * @param v0Z
     *            the z coordinate of the first position
     * @param v1X
     *            the x coordinate of the second position
     * @param v1Y
     *            the y coordinate of the second position
     * @param v1Z
     *            the z coordinate of the second position
     * @param v2X
     *            the x coordinate of the third position
     * @param v2Y
     *            the y coordinate of the third position
     * @param v2Z
     *            the z coordinate of the third position
     * @param dest
     *            will hold the result
     */
    public static void normal(float v0X, float v0Y, float v0Z, float v1X, float v1Y, float v1Z, float v2X, float v2Y, float v2Z, Vector3f dest) {
        dest.x = ((v1Y - v0Y) * (v2Z - v0Z)) - ((v1Z - v0Z) * (v2Y - v0Y));
        dest.y = ((v1Z - v0Z) * (v2X - v0X)) - ((v1X - v0X) * (v2Z - v0Z));
        dest.z = ((v1X - v0X) * (v2Y - v0Y)) - ((v1Y - v0Y) * (v2X - v0X));
        dest.normalize();
    }

    /**
     * Calculate the surface tangent for the three supplied vertices and UV coordinates and store the result in <code>dest</code>.
     *
     * @param v1
     *            XYZ of first vertex
     * @param uv1
     *            UV of first vertex
     * @param v2
     *            XYZ of second vertex
     * @param uv2
     *            UV of second vertex
     * @param v3
     *            XYZ of third vertex
     * @param uv3
     *            UV of third vertex
     * @param dest
     *            the tangent will be stored here
     */
    public static void tangent(Vector3fc v1, Vector2fc uv1, Vector3fc v2, Vector2fc uv2, Vector3fc v3, Vector2fc uv3, Vector3f dest) {
        float DeltaV1 = uv2.y() - uv1.y();
        float DeltaV2 = uv3.y() - uv1.y();

        float f = 1.0f / ((uv2.x() - uv1.x()) * DeltaV2 - (uv3.x() - uv1.x()) * DeltaV1);

        dest.x = f * (DeltaV2 * (v2.x() - v1.x()) - DeltaV1 * (v3.x() - v1.x()));
        dest.y = f * (DeltaV2 * (v2.y() - v1.y()) - DeltaV1 * (v3.y() - v1.y()));
        dest.z = f * (DeltaV2 * (v2.z() - v1.z()) - DeltaV1 * (v3.z() - v1.z()));
        dest.normalize();
    }

    /**
     * Calculate the surface bitangent for the three supplied vertices and UV coordinates and store the result in <code>dest</code>.
     *
     * @param v1
     *            XYZ of first vertex
     * @param uv1
     *            UV of first vertex
     * @param v2
     *            XYZ of second vertex
     * @param uv2
     *            UV of second vertex
     * @param v3
     *            XYZ of third vertex
     * @param uv3
     *            UV of third vertex
     * @param dest
     *            the binormal will be stored here
     */
    public static void bitangent(Vector3fc v1, Vector2fc uv1, Vector3fc v2, Vector2fc uv2, Vector3fc v3, Vector2fc uv3, Vector3f dest) {
        float DeltaU1 = uv2.x() - uv1.x();
        float DeltaU2 = uv3.x() - uv1.x();

        float f = 1.0f / (DeltaU1 * (uv3.y() - uv1.y()) - DeltaU2 * (uv2.y() - uv1.y()));

        dest.x = f * (-DeltaU2 * (v2.x() - v1.x()) + DeltaU1 * (v3.x() - v1.x()));
        dest.y = f * (-DeltaU2 * (v2.y() - v1.y()) + DeltaU1 * (v3.y() - v1.y()));
        dest.z = f * (-DeltaU2 * (v2.z() - v1.z()) + DeltaU1 * (v3.z() - v1.z()));
        dest.normalize();
    }

    /**
     * Calculate the surface tangent and bitangent for the three supplied vertices and UV coordinates and store the result in <code>dest</code>.
     *
     * @param v1
     *            XYZ of first vertex
     * @param uv1
     *            UV of first vertex
     * @param v2
     *            XYZ of second vertex
     * @param uv2
     *            UV of second vertex
     * @param v3
     *            XYZ of third vertex
     * @param uv3
     *            UV of third vertex
     * @param destTangent
     *            the tangent will be stored here
     * @param destBitangent
     *            the bitangent will be stored here
     */
    public static void tangentBitangent(Vector3fc v1, Vector2fc uv1, Vector3fc v2, Vector2fc uv2, Vector3fc v3, Vector2fc uv3, Vector3f destTangent, Vector3f destBitangent) {
        float DeltaV1 = uv2.y() - uv1.y();
        float DeltaV2 = uv3.y() - uv1.y();
        float DeltaU1 = uv2.x() - uv1.x();
        float DeltaU2 = uv3.x() - uv1.x();

        float f = 1.0f / (DeltaU1 * DeltaV2 - DeltaU2 * DeltaV1);

        destTangent.x = f * (DeltaV2 * (v2.x() - v1.x()) - DeltaV1 * (v3.x() - v1.x()));
        destTangent.y = f * (DeltaV2 * (v2.y() - v1.y()) - DeltaV1 * (v3.y() - v1.y()));
        destTangent.z = f * (DeltaV2 * (v2.z() - v1.z()) - DeltaV1 * (v3.z() - v1.z()));
        destTangent.normalize();

        destBitangent.x = f * (-DeltaU2 * (v2.x() - v1.x()) + DeltaU1 * (v3.x() - v1.x()));
        destBitangent.y = f * (-DeltaU2 * (v2.y() - v1.y()) + DeltaU1 * (v3.y() - v1.y()));
        destBitangent.z = f * (-DeltaU2 * (v2.z() - v1.z()) + DeltaU1 * (v3.z() - v1.z()));
        destBitangent.normalize();
    }

}