gtkradiant/libs/mathlib/bbox.c

/*
Copyright (C) 1999-2007 id Software, Inc. and contributors.
For a list of contributors, see the accompanying CONTRIBUTORS file.

This file is part of GtkRadiant.

GtkRadiant is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

GtkRadiant is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <float.h>

#include "mathlib.h"

void aabb_construct_for_vec3(aabb_t *aabb, const vec3_t min, const vec3_t max)
{
  VectorMid(min, max, aabb->origin);
  VectorSubtract(max, aabb->origin, aabb->extents);
}

void aabb_update_radius(aabb_t *aabb)
{
  aabb->radius = VectorLength(aabb->extents);
}

void aabb_clear(aabb_t *aabb)
{
  aabb->origin[0] = aabb->origin[1] = aabb->origin[2] = 0;
  aabb->extents[0] = aabb->extents[1] = aabb->extents[2] = -FLT_MAX;
}

void aabb_extend_by_point(aabb_t *aabb, const vec3_t point)
{
  int i;
  vec_t min, max, displacement;
  for(i=0; i<3; i++)
  {
    displacement = point[i] - aabb->origin[i];
    if(fabs(displacement) > aabb->extents[i])
    {
      if(aabb->extents[i] < 0) // degenerate
      {
        min = max = point[i];
      }
      else if(displacement > 0)
      {
        min = aabb->origin[i] - aabb->extents[i];
        max = aabb->origin[i] + displacement;
      }
      else
      {
        max = aabb->origin[i] + aabb->extents[i];
        min = aabb->origin[i] + displacement;
      }
      aabb->origin[i] = (min + max) * 0.5f;
      aabb->extents[i] = max - aabb->origin[i];
    }
  }
}

void aabb_extend_by_aabb(aabb_t *aabb, const aabb_t *aabb_src)
{
  int i;
  vec_t min, max, displacement, difference;
  for(i=0; i<3; i++)
  {
    displacement = aabb_src->origin[i] - aabb->origin[i];
    difference = aabb_src->extents[i] - aabb->extents[i];
    if(aabb->extents[i] < 0
      || difference >= fabs(displacement))
    {
      // 2nd contains 1st
      aabb->extents[i] = aabb_src->extents[i];
      aabb->origin[i] = aabb_src->origin[i];
    }
    else if(aabb_src->extents[i] < 0
      || -difference >= fabs(displacement))
    {
      // 1st contains 2nd
      continue;
    }
    else
    {
      // not contained
      if(displacement > 0)
      {
        min = aabb->origin[i] - aabb->extents[i];
        max = aabb_src->origin[i] + aabb_src->extents[i];
      }
      else
      {
        min = aabb_src->origin[i] - aabb_src->extents[i];
        max = aabb->origin[i] + aabb->extents[i];
      }
      aabb->origin[i] = (min + max) * 0.5f;
      aabb->extents[i] = max - aabb->origin[i];
    }
  }
}

void aabb_extend_by_vec3(aabb_t *aabb, vec3_t extension)
{
  VectorAdd(aabb->extents, extension, aabb->extents);
}

int aabb_intersect_point(const aabb_t *aabb, const vec3_t point)
{
  int i;
  for(i=0; i<3; i++)
    if(fabs(point[i] - aabb->origin[i]) >= aabb->extents[i])
      return 0;
  return 1;
}

int aabb_intersect_aabb(const aabb_t *aabb, const aabb_t *aabb_src)
{
  int i;
  for (i=0; i<3; i++)
    if ( fabs(aabb_src->origin[i] - aabb->origin[i]) > (fabs(aabb->extents[i]) + fabs(aabb_src->extents[i])) )
      return 0;
  return 1;
}

int aabb_intersect_plane(const aabb_t *aabb, const float *plane)
{
  float fDist, fIntersect;

  // calc distance of origin from plane
  fDist = DotProduct(plane, aabb->origin) + plane[3];
  
  // trivial accept/reject using bounding sphere
	if (fabs(fDist) > aabb->radius)
	{
		if (fDist < 0)
			return 2; // totally inside
		else
			return 0; // totally outside
	}

  // calc extents distance relative to plane normal
  fIntersect = (vec_t)(fabs(plane[0] * aabb->extents[0]) + fabs(plane[1] * aabb->extents[1]) + fabs(plane[2] * aabb->extents[2]));
  // accept if origin is less than or equal to this distance
  if (fabs(fDist) < fIntersect) return 1; // partially inside
  else if (fDist < 0) return 2; // totally inside
  return 0; // totally outside
}

/* 
Fast Ray-Box Intersection
by Andrew Woo
from "Graphics Gems", Academic Press, 1990
*/

#define NUMDIM	3
#define RIGHT	0
#define LEFT	1
#define MIDDLE	2

int aabb_intersect_ray(const aabb_t *aabb, const ray_t *ray, vec_t *dist)
{
	int inside = 1;
	char quadrant[NUMDIM];
	register int i;
	int whichPlane;
	double maxT[NUMDIM];
	double candidatePlane[NUMDIM];
  vec3_t coord, segment;
  
  const float *origin = ray->origin;
  const float *direction = ray->direction;

	/* Find candidate planes; this loop can be avoided if
   	rays cast all from the eye(assume perpsective view) */
	for (i=0; i<NUMDIM; i++)
  {
		if(origin[i] < (aabb->origin[i] - aabb->extents[i]))
    {
			quadrant[i] = LEFT;
			candidatePlane[i] = (aabb->origin[i] - aabb->extents[i]);
			inside = 0;
		}
    else if (origin[i] > (aabb->origin[i] + aabb->extents[i]))
    {
			quadrant[i] = RIGHT;
			candidatePlane[i] = (aabb->origin[i] + aabb->extents[i]);
			inside = 0;
		}
    else
    {
			quadrant[i] = MIDDLE;
    }
  }

	/* Ray origin inside bounding box */
	if(inside == 1)
  {
		*dist = 0.0f;
		return 1;
	}


	/* Calculate T distances to candidate planes */
	for (i = 0; i < NUMDIM; i++)
  {
		if (quadrant[i] != MIDDLE && direction[i] !=0.)
			maxT[i] = (candidatePlane[i] - origin[i]) / direction[i];
		else
			maxT[i] = -1.;
  }

	/* Get largest of the maxT's for final choice of intersection */
	whichPlane = 0;
	for (i = 1; i < NUMDIM; i++)
		if (maxT[whichPlane] < maxT[i])
			whichPlane = i;

	/* Check final candidate actually inside box */
	if (maxT[whichPlane] < 0.)
    return 0;
	for (i = 0; i < NUMDIM; i++)
  {
		if (whichPlane != i)
    {
			coord[i] = (vec_t)(origin[i] + maxT[whichPlane] * direction[i]);
			if (fabs(coord[i] - aabb->origin[i]) > aabb->extents[i])
				return 0;
		}
    else
    {
			coord[i] = (vec_t)candidatePlane[i];
		}
  }

  VectorSubtract(coord, origin, segment);
  *dist = DotProduct(segment, direction);

	return 1;				/* ray hits box */
}

int aabb_test_ray(const aabb_t* aabb, const ray_t* ray)
{
 vec3_t displacement, ray_absolute;
 vec_t f;
 
 displacement[0] = ray->origin[0] - aabb->origin[0];
 if(fabs(displacement[0]) > aabb->extents[0] && displacement[0] * ray->direction[0] >= 0.0f)
   return 0;
 
 displacement[1] = ray->origin[1] - aabb->origin[1];
 if(fabs(displacement[1]) > aabb->extents[1] && displacement[1] * ray->direction[1] >= 0.0f)
   return 0;
 
 displacement[2] = ray->origin[2] - aabb->origin[2];
 if(fabs(displacement[2]) > aabb->extents[2] && displacement[2] * ray->direction[2] >= 0.0f)
   return 0;
 
 ray_absolute[0] = (float)fabs(ray->direction[0]);
 ray_absolute[1] = (float)fabs(ray->direction[1]);
 ray_absolute[2] = (float)fabs(ray->direction[2]);

 f = ray->direction[1] * displacement[2] - ray->direction[2] * displacement[1];
 if((float)fabs(f) > aabb->extents[1] * ray_absolute[2] + aabb->extents[2] * ray_absolute[1])
   return 0;

 f = ray->direction[2] * displacement[0] - ray->direction[0] * displacement[2];
 if((float)fabs(f) > aabb->extents[0] * ray_absolute[2] + aabb->extents[2] * ray_absolute[0])
   return 0;

 f = ray->direction[0] * displacement[1] - ray->direction[1] * displacement[0];
 if((float)fabs(f) > aabb->extents[0] * ray_absolute[1] + aabb->extents[1] * ray_absolute[0])
   return 0;
 
 return 1;
}

void aabb_for_bbox(aabb_t *aabb, const bbox_t *bbox)
{
	int i;
	vec3_t temp[3];

  VectorCopy(bbox->aabb.origin, aabb->origin);

	// calculate the AABB extents in local coord space from the OBB extents and axes
	VectorScale(bbox->axes[0], bbox->aabb.extents[0], temp[0]);
	VectorScale(bbox->axes[1], bbox->aabb.extents[1], temp[1]);
	VectorScale(bbox->axes[2], bbox->aabb.extents[2], temp[2]);
	for(i=0;i<3;i++) aabb->extents[i] = (vec_t)(fabs(temp[0][i]) + fabs(temp[1][i]) + fabs(temp[2][i]));
}

void aabb_for_area(aabb_t *aabb, vec3_t area_tl, vec3_t area_br, int axis)
{
  aabb_clear(aabb);
  aabb->extents[axis] = FLT_MAX;
  aabb_extend_by_point(aabb, area_tl);
  aabb_extend_by_point(aabb, area_br);
}

void aabb_for_transformed_aabb(aabb_t* dst, const aabb_t* src, const m4x4_t transform)
{
  VectorCopy(src->origin, dst->origin);
  m4x4_transform_point(transform, dst->origin);

  dst->extents[0] = (vec_t)(fabs(transform[0]  * src->extents[0])
                          + fabs(transform[4]  * src->extents[1])
                          + fabs(transform[8]  * src->extents[2]));
  dst->extents[1] = (vec_t)(fabs(transform[1]  * src->extents[0])
                          + fabs(transform[5]  * src->extents[1])
                          + fabs(transform[9]  * src->extents[2]));
  dst->extents[2] = (vec_t)(fabs(transform[2]  * src->extents[0])
                          + fabs(transform[6]  * src->extents[1])
                          + fabs(transform[10] * src->extents[2]));
}


void bbox_for_oriented_aabb(bbox_t *bbox, const aabb_t *aabb, const m4x4_t matrix, const vec3_t euler, const vec3_t scale)
{
	double rad[3];
	double pi_180 = Q_PI / 180;
  double A, B, C, D, E, F, AD, BD;
  
	VectorCopy(aabb->origin, bbox->aabb.origin);
	
  m4x4_transform_point(matrix, bbox->aabb.origin);

	bbox->aabb.extents[0] = aabb->extents[0] * scale[0];
	bbox->aabb.extents[1] = aabb->extents[1] * scale[1];
	bbox->aabb.extents[2] = aabb->extents[2] * scale[2];

  rad[0] = euler[0] * pi_180;
	rad[1] = euler[1] * pi_180;
	rad[2] = euler[2] * pi_180;

  A       = cos(rad[0]);
  B       = sin(rad[0]);
  C       = cos(rad[1]);
  D       = sin(rad[1]);
  E       = cos(rad[2]);
  F       = sin(rad[2]);

  AD      =   A * -D;
  BD      =   B * -D;

	bbox->axes[0][0] = (vec_t)(C*E);
	bbox->axes[0][1] = (vec_t)(-BD*E + A*F);
	bbox->axes[0][2] = (vec_t)(AD*E + B*F);
	bbox->axes[1][0] = (vec_t)(-C*F);
	bbox->axes[1][1] = (vec_t)(BD*F + A*E);
	bbox->axes[1][2] = (vec_t)(-AD*F + B*E);
	bbox->axes[2][0] = (vec_t)D;
	bbox->axes[2][1] = (vec_t)(-B*C);
	bbox->axes[2][2] = (vec_t)(A*C);

  aabb_update_radius(&bbox->aabb);
}

int bbox_intersect_plane(const bbox_t *bbox, const vec_t* plane)
{
  vec_t fDist, fIntersect;

  // calc distance of origin from plane
  fDist = DotProduct(plane, bbox->aabb.origin) + plane[3];

	// trivial accept/reject using bounding sphere
	if (fabs(fDist) > bbox->aabb.radius)
	{
		if (fDist < 0)
			return 2; // totally inside
		else
			return 0; // totally outside
	}

  // calc extents distance relative to plane normal
  fIntersect = (vec_t)(fabs(bbox->aabb.extents[0] * DotProduct(plane, bbox->axes[0]))
             + fabs(bbox->aabb.extents[1] * DotProduct(plane, bbox->axes[1]))
             + fabs(bbox->aabb.extents[2] * DotProduct(plane, bbox->axes[2])));
  // accept if origin is less than this distance
  if (fabs(fDist) < fIntersect) return 1; // partially inside
  else if (fDist < 0) return 2; // totally inside
  return 0; // totally outside
}