1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
#include "gravitationalsingularityaffector.h"
#include <cmath>
#include <QDebug>
QT_BEGIN_NAMESPACE
GravitationalSingularityAffector::GravitationalSingularityAffector(QSGItem *parent) :
ParticleAffector(parent), m_strength(0.0), m_x(0), m_y(0)
{
}
const qreal LIMIT = 200;
qreal limit(qreal val){
if(qAbs(val) > LIMIT){
return val < 0 ? LIMIT * -1 : LIMIT;
}else{
return val;
}
}
bool GravitationalSingularityAffector::affectParticle(ParticleData *d, qreal dt)
{
if(!m_strength)
return false;
qreal dx = m_x - d->curX();
qreal dy = m_y - d->curY();
qreal r = sqrt((dx*dx) + (dy*dy));
if(r < 0.1 ){//Simulated event horizion - It's right on top of it, and will never escape again. just stick it here.
d->pv.ax = 0;
d->pv.ay = 0;
d->pv.sx = 0;
d->pv.sy = 0;
d->pv.x = m_x;
d->pv.y = m_y;
return true;
}else if(r < 50.0){//Too close, typical dt values are far too coarse for simulation. This may kill perf though
int parts = floor(100.0/r);
ParticleData* f = new ParticleData;//Fake, where it's all in real time for convenience
f->pv.x = d->curX();
f->pv.y = d->curY();
f->pv.sx = limit(d->curSX());
f->pv.sy = limit(d->curSY());
f->pv.ax = d->pv.ax;
f->pv.ay = d->pv.ay;
subaffect(f, dt/parts, true);
for(int i=1; i<parts; i++)
subaffect(f, dt/parts, false);
//Copy values from f, and turn into 'from start' values
qreal t = (m_system->m_timeInt/1000.) - d->pv.t;
qreal sy = limit(f->pv.sy) - t*f->pv.ay;
qreal y = f->pv.y - t*sy - 0.5 * t*t*f->pv.ay;
qreal sx = limit(f->pv.sx) - t*f->pv.ax;
qreal x = f->pv.x - t*sx - 0.5 * t*t*f->pv.ax;
d->pv.ay = f->pv.ay;
d->pv.sy = sy;
d->pv.y = y;
d->pv.ax = f->pv.ax;
d->pv.sx = sx;
d->pv.x = x;
return true;
}
qreal theta = atan2(dy,dx);
qreal ds = (m_strength / (r*r)) * dt;
dx = ds * cos(theta);
dy = ds * sin(theta);
d->setInstantaneousSX(limit(d->pv.sx + dx));
d->setInstantaneousSY(limit(d->pv.sy + dy));
return true;
}
const qreal EPSILON = 0.1;
bool fuzzyCompare(qreal a, qreal b)
{
//Not using qFuzzyCompare because I want control of epsilon
return (a >= b - EPSILON && a <= b + EPSILON);
}
bool fuzzyLess(qreal a, qreal b)
{
//Not using qFuzzyCompare because I want control of epsilon
return a <= b + EPSILON;
}
bool fuzzyMore(qreal a, qreal b)
{
//Not using qFuzzyCompare because I want control of epsilon
return a >= b - EPSILON;
}
bool lineIntersect(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3)
{
if(x3 < qMin(x1,x2) || x3 > qMax(x1,x2) || y3 < qMin(y1,y2) || y3 > qMax(y1,y2))
return false;
qreal m,c;
m = (y2-y1) / (x2-x1);
c = y1 - m*x1;
return (fuzzyCompare(y3, m*x3 + c));
}
void GravitationalSingularityAffector::subaffect(ParticleData *d, qreal dt, bool first)
{
if(!first){
qreal nextX = d->pv.x + d->pv.sx * dt + d->pv.ax * dt * dt * 0.5;
qreal nextY = d->pv.y + d->pv.sy * dt + d->pv.ay * dt * dt * 0.5;
if(lineIntersect(d->pv.x, d->pv.y, nextX, nextY, m_x, m_y)){
d->pv.ax = 0;
d->pv.ay = 0;
d->pv.sx = 0;
d->pv.sy = 0;
d->pv.x = m_x;
d->pv.y = m_y;
return;
//Passed center - the near infinite forces cancel out
// d->pv.x = m_x + m_x - d->pv.x;
// d->pv.y = m_y + m_y - d->pv.y;
// d->pv.sx *= -1;
// d->pv.sy *= -1;
// return;
}
//Simulate advancing a dt
d->pv.x = nextX;
d->pv.y = nextY;
d->pv.sx += d->pv.ax * dt;
d->pv.sy += d->pv.ay * dt;
}
qreal dx = m_x - d->pv.x;
qreal dy = m_y - d->pv.y;
qreal r = sqrt((dx*dx) + (dy*dy));
if(!r)
return;
qreal theta = atan2(dy,dx);
qreal ds = (m_strength / (r*r)) * dt;
dx = ds * cos(theta);
dy = ds * sin(theta);
d->pv.sx = d->pv.sx + dx;
d->pv.sy = d->pv.sy + dy;
}
QT_END_NAMESPACE
|
