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/*
* The Mana World Server
* Copyright 2004 The Mana World Development Team
*
* This file is part of The Mana World.
*
* The Mana World 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 any later version.
*
* The Mana World 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 The Mana World; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id$
*/
#include "collisiondetection.hpp"
#include <cmath>
#include "point.h"
#include "utils/mathutils.h"
bool
Collision::circleWithCirclesector(const Point &circlePos, int circleRadius,
const Point &secPos, int secRadius,
float secAngle, float secSize)
{
float targetAngle;
// Calculate distance
int distX = circlePos.x - secPos.x;
int distY = circlePos.y - secPos.y;
float invDist = utils::math::fastInvSqrt(distX * distX + distY * distY);
float dist = 1.0f / invDist;
// If out of range we can't hit it
if (dist > secRadius + circleRadius) {
return false;
}
// If we are standing in it we hit it in any case
if (dist < circleRadius) {
return true;
}
// Calculate target angle
if (distX > 0)
{
targetAngle = asin(-distY * invDist);
} else {
if (distY < 0)
{
targetAngle = M_PI - asin(-distY * invDist);
} else {
targetAngle = -M_PI - asin(-distY * invDist);
}
}
// Calculate difference from segment angle
float targetDiff = fabs(targetAngle - secAngle);
if (targetDiff > M_PI)
{
targetDiff = fabs(targetDiff - M_PI * 2);
}
// Add hit circle
secSize += asin(circleRadius * invDist) * 2;
return (targetDiff < secSize * 0.5f);
}
/**
* Collision of a Disk with a Circle-Sector
*
* For a detailled explanation of this function please see:
* http://wiki.themanaworld.org/index.php/Collision_determination
*/
bool
Collision::diskWithCircleSector(const Point &diskCenter, int diskRadius,
const Point §orCenter, int sectorRadius,
int halfTopAngle, int placeAngle)
{
// Converting the radii to float
float R = (float) sectorRadius;
float Rp = (float) diskRadius;
// Transform to the primary coordinate system
float Px = diskCenter.x - sectorCenter.x;
float Py = diskCenter.y - sectorCenter.y;
// The values of the trigonomic functions (only have to be computed once)
float sinAlpha = utils::math::cachedSin(halfTopAngle);
float cosAlpha = utils::math::cachedCos(halfTopAngle);
float sinBeta = utils::math::cachedSin(placeAngle);
float cosBeta = utils::math::cachedCos(placeAngle);
/**
* This bounding circle implementation can be used up and until a
* half-top-angle of +/- 85 degrees. The bounding circle becomes
* infinitly large at 90 degrees. Above about 60 degrees a bounding
* half-circle with radius R becomes more efficient.
* (The additional check for a region 1 collision can then be scrapped.)
*/
// Calculating the coordinates of the disk's center in coordinate system 4
float Px1 = Px * cosBeta + Py * sinBeta;
float Py1 = Py * cosBeta - Px * sinBeta;
// Check for an intersection with the bounding circle
// (>) : touching is accepted
if ((cosAlpha * Px1 * Px1 + cosAlpha * Py1 * Py1 - Px1 * R)
> (Rp * Rp * cosAlpha + Rp * R)) return false;
// Check for a region 4 collision
if ((Px*Px + Py*Py) <= (Rp*Rp)) return true;
// Calculating the coordinates of the disk's center in coordinate system 1
Px1 = Px * (cosAlpha * cosBeta + sinAlpha * sinBeta)
+ Py * (cosAlpha * sinBeta - sinAlpha * cosBeta);
Py1 = Py * (cosAlpha * cosBeta + sinAlpha * sinBeta)
- Px * (cosAlpha * sinBeta - sinAlpha * cosBeta);
// Check if P is in region 5 (using coordinate system 1)
if ((Px1 >= 0.0f) && (Px1 <= R) && (Py1 <= 0.0f))
{
// Return true on intersection, false otherwise
// (>=) : touching is accepted
return (Py1 >= -1.0f * Rp);
}
// Check if P is in region 3 (using coordinate system 1)
if ((Px1 > R) && (Py1 <= 0.0f))
{
// Calculating the vector from point A to the disk center
float distAx = Px - R * (cosAlpha * cosBeta + sinAlpha * sinBeta);
float distAy = Py - R * (cosAlpha * sinBeta - sinAlpha * cosBeta);
// Check for a region 3 collision
return ((distAx * distAx + distAy * distAy) <= Rp * Rp);
}
// Discard, if P is in region 4 (was previously checked)
if ((Px1 < 0.0f) && (Py1 <= 0.0f)) return false;
float tan2Alpha = utils::math::cachedTan(2 * halfTopAngle);
// Check if P is in region 1 (using coordinate system 1)
if ((Px1 >= 0.0f) && (Py1 >= 0.0f) && (Py1 <= Px1 * tan2Alpha))
{
// Return true on intersection, false otherwise
// (<=) : touching is accepted
return ((Px * Px + Py * Py) <= (R * R + Rp * Rp + 2.0f * R * Rp));
}
// Calculating the coordinates of the disk's center in coordinate system 3
Px1 = Px * (cosAlpha * cosBeta - sinAlpha * sinBeta)
+ Py * (sinAlpha * cosBeta + cosAlpha * sinBeta);
Py1 = Py * (cosAlpha * cosBeta - sinAlpha * sinBeta)
- Px * (sinAlpha * cosBeta + cosAlpha * sinBeta);
// Discard, if P is in region 4 (was previously checked)
if ((Px1 < 0.0f) && (Py1 >= 0.0f)) return false;
// Check if P is in region 6 (using coordinate system 3)
if ((Px1 >= 0.0f) && (Px1 <= R) && (Py1 >= 0.0f))
{
// Return true on intersection, false otherwise
// (<=) : touching is accepted
return (Py1 <= Rp);
}
// Check if P is in region 2 (using coordinate system 3)
if ((Px1 > R) && (Py1 <= 0.0f))
{
// Calculating the vector from point B to the disk center
float distBx = Px - R * (cosAlpha * cosBeta - sinAlpha * sinBeta);
float distBy = Py - R * (cosAlpha * sinBeta + sinAlpha * cosBeta);
// Check for a region 2 collision
return ((distBx * distBx + distBy * distBy) <= (Rp * Rp));
}
// The intersection with the bounding circle is in region 4,
// but the disk and circle sector don't intersect.
return false;
}
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