virtualx-engine/core/math/face3.cpp

/*************************************************************************/
/*  face3.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 "face3.h"
#include "geometry.h"

int Face3::split_by_plane(const Plane& p_plane,Face3 p_res[3],bool p_is_point_over[3]) const {

	ERR_FAIL_COND_V(is_degenerate(),0);


        Vector3 above[4];
	int above_count=0;

	Vector3 below[4];
	int below_count=0;

	for (int i=0;i<3;i++) {

		if (p_plane.has_point( vertex[i], CMP_EPSILON )) { // point is in plane

			ERR_FAIL_COND_V(above_count>=4,0);
			above[above_count++]=vertex[i];
			ERR_FAIL_COND_V(below_count>=4,0);
			below[below_count++]=vertex[i];

		} else {

			if (p_plane.is_point_over( vertex[i])) {
				//Point is over
				ERR_FAIL_COND_V(above_count>=4,0);
				above[above_count++]=vertex[i];

			} else {
				//Point is under
				ERR_FAIL_COND_V(below_count>=4,0);
				below[below_count++]=vertex[i];
			}

			/* Check for Intersection between this and the next vertex*/

			Vector3 inters;
			if (!p_plane.intersects_segment( vertex[i],vertex[(i+1)%3],&inters))
				continue;

			/* Intersection goes to both */
			ERR_FAIL_COND_V(above_count>=4,0);
			above[above_count++]=inters;
			ERR_FAIL_COND_V(below_count>=4,0);
			below[below_count++]=inters;
		}
	}

	int polygons_created=0;

	ERR_FAIL_COND_V( above_count>=4 && below_count>=4 , 0 ); //bug in the algo

	if (above_count>=3) {

		p_res[polygons_created]=Face3( above[0], above[1], above[2] );
		p_is_point_over[polygons_created]=true;
		polygons_created++;

		if (above_count==4) {

			p_res[polygons_created]=Face3( above[2], above[3], above[0] );
			p_is_point_over[polygons_created]=true;
			polygons_created++;

		}
	}

	if (below_count>=3) {

		p_res[polygons_created]=Face3( below[0], below[1], below[2] );
		p_is_point_over[polygons_created]=false;
		polygons_created++;

		if (below_count==4) {

			p_res[polygons_created]=Face3( below[2], below[3], below[0] );
			p_is_point_over[polygons_created]=false;
			polygons_created++;

		}
	}

	return polygons_created;
}



bool Face3::intersects_ray(const Vector3& p_from,const Vector3& p_dir,Vector3 * p_intersection) const {

	return Geometry::ray_intersects_triangle(p_from,p_dir,vertex[0],vertex[1],vertex[2],p_intersection);

}

bool Face3::intersects_segment(const Vector3& p_from,const Vector3& p_dir,Vector3 * p_intersection) const {

	return Geometry::segment_intersects_triangle(p_from,p_dir,vertex[0],vertex[1],vertex[2],p_intersection);

}


bool Face3::is_degenerate() const {

	Vector3 normal=vec3_cross(vertex[0]-vertex[1], vertex[0]-vertex[2]);
	return (normal.length_squared() < CMP_EPSILON2);
}


Face3::Side Face3::get_side_of(const Face3& p_face,ClockDirection p_clock_dir) const {

	int over=0,under=0;

	Plane plane=get_plane(p_clock_dir);

	for (int i=0;i<3;i++) {

		const Vector3 &v=p_face.vertex[i];

		if (plane.has_point(v)) //coplanar, dont bother
			continue;

		if (plane.is_point_over(v))
			over++;
		else
			under++;

	}

	if ( over > 0 && under == 0 )
		return SIDE_OVER;
	else if (under > 0 && over ==0 )
		return SIDE_UNDER;
	else if (under ==0 && over == 0)
		return SIDE_COPLANAR;
	else
		return SIDE_SPANNING;

}

Vector3 Face3::get_random_point_inside() const {

	float a=Math::random(0,1);
	float b=Math::random(0,1);
	if (a>b) {
		SWAP(a,b);
	}

	return vertex[0]*a + vertex[1]*(b-a) + vertex[2]*(1.0-b);

}

Plane Face3::get_plane(ClockDirection p_dir) const {

	return Plane( vertex[0], vertex[1], vertex[2] , p_dir );

}

Vector3 Face3::get_median_point() const {

	return (vertex[0] + vertex[1] + vertex[2])/3.0;
}


real_t Face3::get_area() const {

	return vec3_cross(vertex[0]-vertex[1], vertex[0]-vertex[2]).length();
}

ClockDirection Face3::get_clock_dir() const {


	Vector3 normal=vec3_cross(vertex[0]-vertex[1], vertex[0]-vertex[2]);
	//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] ) ) );
	return ( normal.dot( vertex[0] ) >= 0 ) ? CLOCKWISE : COUNTERCLOCKWISE;

}


bool Face3::intersects_aabb(const AABB& p_aabb) const {

	/** TEST PLANE **/
	if (!p_aabb.intersects_plane( get_plane() ))
		return false;

	/** TEST FACE AXIS */

#define TEST_AXIS(m_ax)\
	{\
		float aabb_min=p_aabb.pos.m_ax;\
		float aabb_max=p_aabb.pos.m_ax+p_aabb.size.m_ax;\
		float tri_min,tri_max;\
		for (int i=0;i<3;i++) {\
			if (i==0 || vertex[i].m_ax > tri_max)\
				tri_max=vertex[i].m_ax;\
			if (i==0 || vertex[i].m_ax < tri_min)\
				tri_min=vertex[i].m_ax;\
		}\
\
		if (tri_max<aabb_min || aabb_max<tri_min)\
			return false;\
	}

	TEST_AXIS(x);
	TEST_AXIS(y);
	TEST_AXIS(z);

	/** TEST ALL EDGES **/

	Vector3 edge_norms[3]={
		vertex[0]-vertex[1],
		vertex[1]-vertex[2],
		vertex[2]-vertex[0],
	};

	for (int i=0;i<12;i++) {

		Vector3 from,to;
		p_aabb.get_edge(i,from,to);
		Vector3 e1=from-to;
		for (int j=0;j<3;j++) {
			Vector3 e2=edge_norms[j];

			Vector3 axis=vec3_cross( e1, e2 );

			if (axis.length_squared()<0.0001)
				continue; // coplanar
			axis.normalize();

			float minA,maxA,minB,maxB;
			p_aabb.project_range_in_plane(Plane(axis,0),minA,maxA);
			project_range(axis,Transform(),minB,maxB);

			if (maxA<minB || maxB<minA)
				return false;
		}
	}
	return true;

}

Face3::operator String() const {

	return String()+vertex[0]+", "+vertex[1]+", "+vertex[2];
}

void Face3::project_range(const Vector3& p_normal,const Transform& p_transform,float& r_min, float& r_max) const {

	for (int i=0;i<3;i++) {

		Vector3 v=p_transform.xform(vertex[i]);
		float d=p_normal.dot(v);

		if (i==0 || d > r_max)
			r_max=d;

		if (i==0 || d < r_min)
			r_min=d;
	}
}



void Face3::get_support(const Vector3& p_normal,const Transform& p_transform,Vector3 *p_vertices,int* p_count,int p_max) const {

#define _FACE_IS_VALID_SUPPORT_TRESHOLD 0.98
#define _EDGE_IS_VALID_SUPPORT_TRESHOLD 0.05

	if (p_max<=0)
		return;

	Vector3 n=p_transform.basis.xform_inv(p_normal);

	/** TEST FACE AS SUPPORT **/
	if (get_plane().normal.dot(n) > _FACE_IS_VALID_SUPPORT_TRESHOLD) {

		*p_count=MIN(3,p_max);

		for (int i=0;i<*p_count;i++) {

			p_vertices[i]=p_transform.xform(vertex[i]);
		}

		return;

	}

	/** FIND SUPPORT VERTEX **/

	int vert_support_idx=-1;
	float support_max;

	for (int i=0;i<3;i++) {

		float d=n.dot(vertex[i]);

		if (i==0 || d > support_max) {
			support_max=d;
			vert_support_idx=i;
		}
	}

	/** TEST EDGES AS SUPPORT **/

	for (int i=0;i<3;i++) {

		if (i!=vert_support_idx && i+1!=vert_support_idx)
			continue;

	// check if edge is valid as a support
		float dot=(vertex[i]-vertex[(i+1)%3]).normalized().dot(n);
		dot=ABS(dot);
		if (dot < _EDGE_IS_VALID_SUPPORT_TRESHOLD) {

			*p_count=MIN(2,p_max);

			for (int j=0;j<*p_count;j++)
				p_vertices[j]=p_transform.xform(vertex[(j+i)%3]);

			return;
		}
	}


	*p_count=1;
	p_vertices[0]=p_transform.xform(vertex[vert_support_idx]);

}


Vector3 Face3::get_closest_point_to(const Vector3& p_point) const {

	    Vector3 edge0 = vertex[1] - vertex[0];
	    Vector3 edge1 = vertex[2] - vertex[0];
	    Vector3 v0 = vertex[0] - p_point;

	    float a = edge0.dot( edge0 );
	    float b = edge0.dot( edge1 );
	    float c = edge1.dot( edge1 );
	    float d = edge0.dot( v0 );
	    float e = edge1.dot( v0 );

	    float det = a*c - b*b;
	    float s = b*e - c*d;
	    float t = b*d - a*e;

	    if ( s + t < det )
	    {
		if ( s < 0.f )
		{
		    if ( t < 0.f )
		    {
			if ( d < 0.f )
			{
			    s = CLAMP( -d/a, 0.f, 1.f );
			    t = 0.f;
			}
			else
			{
			    s = 0.f;
			    t = CLAMP( -e/c, 0.f, 1.f );
			}
		    }
		    else
		    {
			s = 0.f;
			t = CLAMP( -e/c, 0.f, 1.f );
		    }
		}
		else if ( t < 0.f )
		{
		    s = CLAMP( -d/a, 0.f, 1.f );
		    t = 0.f;
		}
		else
		{
		    float invDet = 1.f / det;
		    s *= invDet;
		    t *= invDet;
		}
	    }
	    else
	    {
		if ( s < 0.f )
		{
		    float tmp0 = b+d;
		    float tmp1 = c+e;
		    if ( tmp1 > tmp0 )
		    {
			float numer = tmp1 - tmp0;
			float denom = a-2*b+c;
			s = CLAMP( numer/denom, 0.f, 1.f );
			t = 1-s;
		    }
		    else
		    {
			t = CLAMP( -e/c, 0.f, 1.f );
			s = 0.f;
		    }
		}
		else if ( t < 0.f )
		{
		    if ( a+d > b+e )
		    {
			float numer = c+e-b-d;
			float denom = a-2*b+c;
			s = CLAMP( numer/denom, 0.f, 1.f );
			t = 1-s;
		    }
		    else
		    {
			s = CLAMP( -e/c, 0.f, 1.f );
			t = 0.f;
		    }
		}
		else
		{
		    float numer = c+e-b-d;
		    float denom = a-2*b+c;
		    s = CLAMP( numer/denom, 0.f, 1.f );
		    t = 1.f - s;
		}
	    }

	    return vertex[0] + s * edge0 + t * edge1;

}