godot/core/math/plane.cpp

/*************************************************************************/
/*  plane.cpp                                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                 */
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#include "plane.h"

#include "math_funcs.h"

#define _PLANE_EQ_DOT_EPSILON 0.999
#define _PLANE_EQ_D_EPSILON 0.0001

void Plane::set_normal(const Vector3& p_normal) {

        normal=p_normal;
}

void Plane::normalize() {

	real_t l = normal.length();
	if (l==0) {
		*this=Plane(0,0,0,0);
		return;
	}
	normal/=l;
	d/=l;
}

Plane Plane::normalized() const {
	
	Plane p = *this;
	p.normalize();
	return p;
}

Vector3 Plane::get_any_point() const {

	return get_normal()*d;
}

Vector3 Plane::get_any_perpendicular_normal() const {

	static const Vector3 p1 = Vector3(1,0,0);
	static const Vector3 p2 = Vector3(0,1,0);
	Vector3 p;
	
	if (ABS(normal.dot(p1)) > 0.99) // if too similar to p1
		p=p2; // use p2
	else
		p=p1; // use p1
	
	p-=normal * normal.dot(p);
	p.normalize();

	return p;
}

/* intersections */

bool Plane::intersect_3(const Plane &p_plane1, const Plane &p_plane2, Vector3 *r_result) const {

	const Plane &p_plane0=*this;
	Vector3 normal0=p_plane0.normal;
	Vector3 normal1=p_plane1.normal;
	Vector3 normal2=p_plane2.normal;

	real_t denom=vec3_cross(normal0,normal1).dot(normal2);

	if (ABS(denom)<=CMP_EPSILON)
		return false;

        if (r_result) {
                *r_result = 	( (vec3_cross(normal1, normal2) * p_plane0.d) +
			(vec3_cross(normal2, normal0) * p_plane1.d) +
			(vec3_cross(normal0, normal1) * p_plane2.d) )/denom;
        }

	return true;
}


bool Plane::intersects_ray(Vector3 p_from, Vector3 p_dir, Vector3* p_intersection)  const {

	Vector3 segment=p_dir;
	real_t den=normal.dot( segment );

	//printf("den is %i\n",den);
	if (Math::abs(den)<=CMP_EPSILON) {

		return false;
	}

	real_t dist=(normal.dot( p_from ) - d) / den;
	//printf("dist is %i\n",dist);

	if (dist>CMP_EPSILON) { //this is a ray, before the emiting pos (p_from) doesnt exist

		return false;
	}

	dist=-dist;
	*p_intersection = p_from + segment * dist;

	return true;
}

bool Plane::intersects_segment(Vector3 p_begin, Vector3 p_end, Vector3* p_intersection)  const {

	Vector3 segment= p_begin - p_end;
	real_t den=normal.dot( segment );

	//printf("den is %i\n",den);
	if (Math::abs(den)<=CMP_EPSILON) {

		return false;
	}

	real_t dist=(normal.dot( p_begin ) - d) / den;
	//printf("dist is %i\n",dist);

	if (dist<-CMP_EPSILON || dist > (1.0 +CMP_EPSILON)) {

		return false;
	}

	dist=-dist;
	*p_intersection = p_begin + segment * dist;

	return true;
}

/* misc */

bool Plane::is_almost_like(const Plane& p_plane) const {

	return (normal.dot( p_plane.normal ) > _PLANE_EQ_DOT_EPSILON && Math::absd(d-p_plane.d) < _PLANE_EQ_D_EPSILON);
}


Plane::operator String() const {

	return normal.operator String() + ", " + rtos(d);
}