f8c4ffcdde
There seemed to be a bug in area calculation in Face3::get_area()-function. It returned the area of "imaginary" parallelogram instead of the triangle. Therefore the area returned was twice the real area. This manifested itself when using a hydro module for godot ( https://gitlab.com/ringtechsolutions/godot-tools/hydro/hydro ) causing the buoyancy to be two times the expected value.
"Reference": http://www.maths.usyd.edu.au/u/MOW/vectors/vectors-11/v-11-7.html
(cherry picked from commit a165eed73b)
408 lines
11 KiB
C++
408 lines
11 KiB
C++
/*************************************************************************/
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/* face3.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#include "face3.h"
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#include "core/math/geometry.h"
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int Face3::split_by_plane(const Plane &p_plane, Face3 p_res[3], bool p_is_point_over[3]) const {
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ERR_FAIL_COND_V(is_degenerate(), 0);
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Vector3 above[4];
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int above_count = 0;
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Vector3 below[4];
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int below_count = 0;
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for (int i = 0; i < 3; i++) {
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if (p_plane.has_point(vertex[i], CMP_EPSILON)) { // point is in plane
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ERR_FAIL_COND_V(above_count >= 4, 0);
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above[above_count++] = vertex[i];
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ERR_FAIL_COND_V(below_count >= 4, 0);
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below[below_count++] = vertex[i];
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} else {
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if (p_plane.is_point_over(vertex[i])) {
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//Point is over
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ERR_FAIL_COND_V(above_count >= 4, 0);
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above[above_count++] = vertex[i];
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} else {
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//Point is under
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ERR_FAIL_COND_V(below_count >= 4, 0);
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below[below_count++] = vertex[i];
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}
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/* Check for Intersection between this and the next vertex*/
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Vector3 inters;
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if (!p_plane.intersects_segment(vertex[i], vertex[(i + 1) % 3], &inters))
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continue;
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/* Intersection goes to both */
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ERR_FAIL_COND_V(above_count >= 4, 0);
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above[above_count++] = inters;
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ERR_FAIL_COND_V(below_count >= 4, 0);
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below[below_count++] = inters;
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}
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}
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int polygons_created = 0;
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ERR_FAIL_COND_V(above_count >= 4 && below_count >= 4, 0); //bug in the algo
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if (above_count >= 3) {
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p_res[polygons_created] = Face3(above[0], above[1], above[2]);
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p_is_point_over[polygons_created] = true;
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polygons_created++;
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if (above_count == 4) {
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p_res[polygons_created] = Face3(above[2], above[3], above[0]);
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p_is_point_over[polygons_created] = true;
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polygons_created++;
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}
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}
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if (below_count >= 3) {
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p_res[polygons_created] = Face3(below[0], below[1], below[2]);
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p_is_point_over[polygons_created] = false;
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polygons_created++;
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if (below_count == 4) {
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p_res[polygons_created] = Face3(below[2], below[3], below[0]);
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p_is_point_over[polygons_created] = false;
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polygons_created++;
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}
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}
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return polygons_created;
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}
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bool Face3::intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, Vector3 *p_intersection) const {
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return Geometry::ray_intersects_triangle(p_from, p_dir, vertex[0], vertex[1], vertex[2], p_intersection);
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}
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bool Face3::intersects_segment(const Vector3 &p_from, const Vector3 &p_dir, Vector3 *p_intersection) const {
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return Geometry::segment_intersects_triangle(p_from, p_dir, vertex[0], vertex[1], vertex[2], p_intersection);
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}
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bool Face3::is_degenerate() const {
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Vector3 normal = vec3_cross(vertex[0] - vertex[1], vertex[0] - vertex[2]);
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return (normal.length_squared() < CMP_EPSILON2);
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}
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Face3::Side Face3::get_side_of(const Face3 &p_face, ClockDirection p_clock_dir) const {
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int over = 0, under = 0;
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Plane plane = get_plane(p_clock_dir);
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for (int i = 0; i < 3; i++) {
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const Vector3 &v = p_face.vertex[i];
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if (plane.has_point(v)) //coplanar, don't bother
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continue;
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if (plane.is_point_over(v))
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over++;
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else
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under++;
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}
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if (over > 0 && under == 0)
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return SIDE_OVER;
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else if (under > 0 && over == 0)
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return SIDE_UNDER;
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else if (under == 0 && over == 0)
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return SIDE_COPLANAR;
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else
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return SIDE_SPANNING;
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}
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Vector3 Face3::get_random_point_inside() const {
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real_t a = Math::random(0, 1);
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real_t b = Math::random(0, 1);
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if (a > b) {
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SWAP(a, b);
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}
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return vertex[0] * a + vertex[1] * (b - a) + vertex[2] * (1.0 - b);
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}
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Plane Face3::get_plane(ClockDirection p_dir) const {
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return Plane(vertex[0], vertex[1], vertex[2], p_dir);
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}
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Vector3 Face3::get_median_point() const {
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return (vertex[0] + vertex[1] + vertex[2]) / 3.0;
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}
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real_t Face3::get_area() const {
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return vec3_cross(vertex[0] - vertex[1], vertex[0] - vertex[2]).length() * 0.5;
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}
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ClockDirection Face3::get_clock_dir() const {
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Vector3 normal = vec3_cross(vertex[0] - vertex[1], vertex[0] - vertex[2]);
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//printf("normal is %g,%g,%g x %g,%g,%g- wtfu is %g\n",tofloat(normal.x),tofloat(normal.y),tofloat(normal.z),tofloat(vertex[0].x),tofloat(vertex[0].y),tofloat(vertex[0].z),tofloat( normal.dot( vertex[0] ) ) );
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return (normal.dot(vertex[0]) >= 0) ? CLOCKWISE : COUNTERCLOCKWISE;
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}
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bool Face3::intersects_aabb(const AABB &p_aabb) const {
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/** TEST PLANE **/
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if (!p_aabb.intersects_plane(get_plane()))
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return false;
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#define TEST_AXIS(m_ax) \
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/** TEST FACE AXIS */ \
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{ \
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real_t aabb_min = p_aabb.position.m_ax; \
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real_t aabb_max = p_aabb.position.m_ax + p_aabb.size.m_ax; \
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real_t tri_min = vertex[0].m_ax; \
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real_t tri_max = vertex[0].m_ax; \
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for (int i = 1; i < 3; i++) { \
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if (vertex[i].m_ax > tri_max) \
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tri_max = vertex[i].m_ax; \
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if (vertex[i].m_ax < tri_min) \
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tri_min = vertex[i].m_ax; \
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} \
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\
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if (tri_max < aabb_min || aabb_max < tri_min) \
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return false; \
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}
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TEST_AXIS(x);
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TEST_AXIS(y);
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TEST_AXIS(z);
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/** TEST ALL EDGES **/
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Vector3 edge_norms[3] = {
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vertex[0] - vertex[1],
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vertex[1] - vertex[2],
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vertex[2] - vertex[0],
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};
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for (int i = 0; i < 12; i++) {
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Vector3 from, to;
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p_aabb.get_edge(i, from, to);
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Vector3 e1 = from - to;
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for (int j = 0; j < 3; j++) {
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Vector3 e2 = edge_norms[j];
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Vector3 axis = vec3_cross(e1, e2);
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if (axis.length_squared() < 0.0001)
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continue; // coplanar
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axis.normalize();
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real_t minA, maxA, minB, maxB;
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p_aabb.project_range_in_plane(Plane(axis, 0), minA, maxA);
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project_range(axis, Transform(), minB, maxB);
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if (maxA < minB || maxB < minA)
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return false;
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}
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}
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return true;
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}
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Face3::operator String() const {
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return String() + vertex[0] + ", " + vertex[1] + ", " + vertex[2];
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}
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void Face3::project_range(const Vector3 &p_normal, const Transform &p_transform, real_t &r_min, real_t &r_max) const {
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for (int i = 0; i < 3; i++) {
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Vector3 v = p_transform.xform(vertex[i]);
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real_t d = p_normal.dot(v);
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if (i == 0 || d > r_max)
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r_max = d;
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if (i == 0 || d < r_min)
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r_min = d;
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}
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}
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void Face3::get_support(const Vector3 &p_normal, const Transform &p_transform, Vector3 *p_vertices, int *p_count, int p_max) const {
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#define _FACE_IS_VALID_SUPPORT_THRESHOLD 0.98
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#define _EDGE_IS_VALID_SUPPORT_THRESHOLD 0.05
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if (p_max <= 0)
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return;
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Vector3 n = p_transform.basis.xform_inv(p_normal);
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/** TEST FACE AS SUPPORT **/
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if (get_plane().normal.dot(n) > _FACE_IS_VALID_SUPPORT_THRESHOLD) {
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*p_count = MIN(3, p_max);
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for (int i = 0; i < *p_count; i++) {
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p_vertices[i] = p_transform.xform(vertex[i]);
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}
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return;
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}
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/** FIND SUPPORT VERTEX **/
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int vert_support_idx = -1;
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real_t support_max = 0;
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for (int i = 0; i < 3; i++) {
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real_t d = n.dot(vertex[i]);
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if (i == 0 || d > support_max) {
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support_max = d;
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vert_support_idx = i;
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}
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}
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/** TEST EDGES AS SUPPORT **/
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for (int i = 0; i < 3; i++) {
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if (i != vert_support_idx && i + 1 != vert_support_idx)
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continue;
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// check if edge is valid as a support
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real_t dot = (vertex[i] - vertex[(i + 1) % 3]).normalized().dot(n);
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dot = ABS(dot);
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if (dot < _EDGE_IS_VALID_SUPPORT_THRESHOLD) {
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*p_count = MIN(2, p_max);
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for (int j = 0; j < *p_count; j++)
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p_vertices[j] = p_transform.xform(vertex[(j + i) % 3]);
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return;
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}
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}
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*p_count = 1;
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p_vertices[0] = p_transform.xform(vertex[vert_support_idx]);
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}
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Vector3 Face3::get_closest_point_to(const Vector3 &p_point) const {
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Vector3 edge0 = vertex[1] - vertex[0];
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Vector3 edge1 = vertex[2] - vertex[0];
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Vector3 v0 = vertex[0] - p_point;
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real_t a = edge0.dot(edge0);
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real_t b = edge0.dot(edge1);
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real_t c = edge1.dot(edge1);
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real_t d = edge0.dot(v0);
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real_t e = edge1.dot(v0);
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real_t det = a * c - b * b;
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real_t s = b * e - c * d;
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real_t t = b * d - a * e;
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if (s + t < det) {
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if (s < 0.f) {
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if (t < 0.f) {
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if (d < 0.f) {
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s = CLAMP(-d / a, 0.f, 1.f);
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t = 0.f;
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} else {
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s = 0.f;
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t = CLAMP(-e / c, 0.f, 1.f);
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}
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} else {
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s = 0.f;
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t = CLAMP(-e / c, 0.f, 1.f);
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}
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} else if (t < 0.f) {
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s = CLAMP(-d / a, 0.f, 1.f);
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t = 0.f;
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} else {
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real_t invDet = 1.f / det;
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s *= invDet;
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t *= invDet;
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}
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} else {
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if (s < 0.f) {
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real_t tmp0 = b + d;
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real_t tmp1 = c + e;
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if (tmp1 > tmp0) {
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real_t numer = tmp1 - tmp0;
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real_t denom = a - 2 * b + c;
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s = CLAMP(numer / denom, 0.f, 1.f);
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t = 1 - s;
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} else {
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t = CLAMP(-e / c, 0.f, 1.f);
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s = 0.f;
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}
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} else if (t < 0.f) {
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if (a + d > b + e) {
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real_t numer = c + e - b - d;
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real_t denom = a - 2 * b + c;
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s = CLAMP(numer / denom, 0.f, 1.f);
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t = 1 - s;
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} else {
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s = CLAMP(-d / a, 0.f, 1.f);
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t = 0.f;
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}
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} else {
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real_t numer = c + e - b - d;
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real_t denom = a - 2 * b + c;
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s = CLAMP(numer / denom, 0.f, 1.f);
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t = 1.f - s;
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}
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}
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return vertex[0] + s * edge0 + t * edge1;
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}
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