-
Notifications
You must be signed in to change notification settings - Fork 0
/
gl_sdl_geometry.cpp
146 lines (119 loc) · 3.94 KB
/
gl_sdl_geometry.cpp
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
139
140
141
142
143
144
145
146
#include "gl_sdl_geometry.hpp"
#include <cmath>
#include <limits>
void rotate_tri(tri *tri, float angle)
{
float s = sinf(angle);
float c = cosf(angle);
for (unsigned int i = 0; i < 3; i++) {
float x = tri->points[i].x;
float y = tri->points[i].y;
tri->points[i] = { x * c - y * s, x * s + y * c };
}
}
void move_tri(tri *tri, vect v)
{
for (unsigned int i = 0; i < 3; i++) {
float x = tri->points[i].x;
float y = tri->points[i].y;
tri->points[i] = { x + v.x, y + v.y };
}
}
void move_rect(rect *rect, vect v)
{
rect->x += v.x;
rect->y += v.y;
}
void move_circle(circle *circle, vect v)
{
circle->center.x += v.x;
circle->center.y += v.y;
}
bool point_in_circle(point p, circle *circle)
{
float dist_x = p.x - circle->center.x;
float dist_y = p.y - circle->center.y;
float dist_sq = dist_x * dist_x + dist_y * dist_y;
return dist_sq <= circle->radius * circle->radius;
}
#define swapf(_x, _y) { float temp = _x; _x = _y; _y = temp; }
bool point_in_rect(point p, rect *rect)
{
float x_min = rect->x;
float x_max = rect->x + rect->w;
float y_min = rect->y;
float y_max = rect->y + rect->h;
if (rect->w < 0.0f)
swapf(x_min, x_max);
if (rect->h < 0.0f)
swapf(y_min, y_max);
return p.x <= x_max && p.x >= x_min && p.y <= y_max && p.y >= y_min;
}
static float cross_z(const vect *v1, const vect *v2)
{
return v1->x * v2->y - v1->y * v2->x;
}
static bool points_on_same_side(const point *p1, const point *p2,
const point *a, const point *b)
{
vect a_p1 = { p1->x - a->x, p1->y - a->y };
vect a_p2 = { p2->x - a->x, p2->y - a->y };
vect a_b = { b->x - a->x, b->y - a->y };
float z1 = cross_z(&a_b, &a_p1);
float z2 = cross_z(&a_b, &a_p2);
return z1 * z2 >= 0;
}
bool point_in_tri(point p, tri *tri)
{
point a = tri->points[0];
point b = tri->points[1];
point c = tri->points[2];
return points_on_same_side(&p, &a, &b, &c) &&
points_on_same_side(&p, &b, &c, &a) &&
points_on_same_side(&p, &c, &a, &b);
}
static float point_point_dist_sq(point p1, point p2)
{
return (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
}
static float line_point_dist_sq(point p1, point p2, point p3)
{
float u = (p3.x - p1.x) * (p2.x - p1.x) + (p3.y - p1.y) * (p2.y - p1.y);
u /= point_point_dist_sq(p1, p2);
point p4 = { p1.x + u * (p2.x - p1.x), p1.y + u * (p2.y - p1.y) };
if (u <= 0.0f) p4 = p1;
else if (u >= 1.0f) p4 = p2;
return point_point_dist_sq(p3, p4);
}
bool intersect(circle *circle_1, circle *circle_2)
{
float r2 = (circle_1->radius + circle_2->radius) *
(circle_1->radius + circle_2->radius);
return point_point_dist_sq(circle_1->center, circle_2->center) < r2;
}
bool intersect(circle *circle, rect *rect)
{
float r2 = circle->radius * circle->radius;
point p1 = { rect->x, rect->y };
point p2 = { rect->x + rect->w, rect->y };
point p3 = { rect->x + rect->w, rect->y + rect->h };
point p4 = { rect->x, rect->y + rect->h };
return point_in_rect(circle->center, rect) ||
line_point_dist_sq(p1, p2, circle->center) < r2 ||
line_point_dist_sq(p2, p3, circle->center) < r2 ||
line_point_dist_sq(p3, p4, circle->center) < r2 ||
line_point_dist_sq(p4, p1, circle->center) < r2;
}
bool intersect(circle *circle, tri *tri)
{
float r2 = circle->radius * circle->radius;
return point_in_tri(circle->center, tri) ||
line_point_dist_sq(tri->points[0], tri->points[1], circle->center) < r2 ||
line_point_dist_sq(tri->points[1], tri->points[2], circle->center) < r2 ||
line_point_dist_sq(tri->points[2], tri->points[0], circle->center) < r2;
}
bool intersect(circle *circle, line *line)
{
float r2 = circle->radius * circle->radius;
return line_point_dist_sq(line->start, line->end, circle->center) < r2;
}