1 // frustum.cpp
2 //
3 // Copyright (C) 2000, Chris Laurel <claurel@shatters.net>
4 //
5 // This program is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU General Public License
7 // as published by the Free Software Foundation; either version 2
8 // of the License, or (at your option) any later version.
9
10 #include "frustum.h"
11
12
Frustum(float fov,float aspectRatio,float n)13 Frustum::Frustum(float fov, float aspectRatio, float n) :
14 infinite(true)
15 {
16 init(fov, aspectRatio, n, n);
17 }
18
19
Frustum(float fov,float aspectRatio,float n,float f)20 Frustum::Frustum(float fov, float aspectRatio, float n, float f) :
21 infinite(false)
22 {
23 init(fov, aspectRatio, n, f);
24 }
25
26
init(float fov,float aspectRatio,float n,float f)27 void Frustum::init(float fov, float aspectRatio, float n, float f)
28 {
29 float h = (float) tan(fov / 2.0f);
30 float w = h * aspectRatio;
31
32 Vec3f normals[4];
33 normals[Bottom] = Vec3f(0, 1, -h);
34 normals[Top] = Vec3f(0, -1, -h);
35 normals[Left] = Vec3f(1, 0, -w);
36 normals[Right] = Vec3f(-1, 0, -w);
37 for (int i = 0; i < 4; i++)
38 {
39 normals[i].normalize();
40 planes[i] = Planef(normals[i], Point3f(0, 0, 0));
41 }
42
43 planes[Near] = Planef(Vec3f(0, 0, -1), -n);
44 planes[Far] = Planef(Vec3f(0, 0, 1), f);
45 }
46
47
test(const Point3f & p) const48 Frustum::Aspect Frustum::test(const Point3f& p) const
49 {
50 return testSphere(p, 0);
51 }
52
53
testSphere(const Point3f & center,float radius) const54 Frustum::Aspect Frustum::testSphere(const Point3f& center, float radius) const
55 {
56 int nPlanes = infinite ? 5 : 6;
57 int intersections = 0;
58
59 for (int i = 0; i < nPlanes; i++)
60 {
61 float distanceToPlane = planes[i].distanceTo(center);
62 if (distanceToPlane < -radius)
63 return Outside;
64 else if (distanceToPlane <= radius)
65 intersections |= (1 << i);
66 }
67
68 return (intersections == 0) ? Inside : Intersect;
69 }
70
71
testSphere(const Point3d & center,double radius) const72 Frustum::Aspect Frustum::testSphere(const Point3d& center, double radius) const
73 {
74 int nPlanes = infinite ? 5 : 6;
75 int intersections = 0;
76
77 for (int i = 0; i < nPlanes; i++)
78 {
79 //TODO: Celestia should incorporate some casting operators overloading to accommodate all this kind of stuff:
80 Vec3f plNormal = planes[i].normal;
81 Vec3d plNormalDbl(plNormal.x, plNormal.y, plNormal.z);
82
83 double distanceToPlane = plNormalDbl.x * center.x + plNormalDbl.y * center.y + plNormalDbl.z * center.z + planes[i].d;
84 if (distanceToPlane < -radius)
85 return Outside;
86 else if (distanceToPlane <= radius)
87 intersections |= (1 << i);
88 }
89
90 return (intersections == 0) ? Inside : Intersect;
91 }
92
93
testCapsule(const Capsulef & capsule) const94 Frustum::Aspect Frustum::testCapsule(const Capsulef& capsule) const
95 {
96 int nPlanes = infinite ? 5 : 6;
97 int intersections = 0;
98 float r2 = capsule.radius * capsule.radius;
99
100 for (int i = 0; i < nPlanes; i++)
101 {
102 float signedDist0 = planes[i].normal * Vec3f(capsule.origin.x, capsule.origin.y, capsule.origin.z) + planes[i].d;
103 float signedDist1 = signedDist0 + planes[i].normal * capsule.axis;
104 if (signedDist0 * signedDist1 > r2)
105 {
106 // Endpoints of capsule are on same side of plane; test closest endpoint to see if it
107 // lies closer to the plane than radius
108 if (abs(signedDist0) <= abs(signedDist1))
109 {
110 if (signedDist0 < -capsule.radius)
111 return Outside;
112 else if (signedDist0 < capsule.radius)
113 intersections |= (1 << i);
114 }
115 else
116 {
117 if (signedDist1 < -capsule.radius)
118 return Outside;
119 else if (signedDist1 < capsule.radius)
120 intersections |= (1 << i);
121 }
122 }
123 else
124 {
125 // Capsule endpoints are on different sides of the plane, so we have an intersection
126 intersections |= (1 << i);
127 }
128 #if 0
129 Vec3f plNormal = planes[i].normal;
130 Vec3d plNormalDbl(plNormal.x, plNormal.y, plNormal.z);
131
132 double distanceToPlane = planes[i].distanceToSegment(capsule.origin, capsule.axis);
133 if (distanceToPlane < -capsule.radius)
134 return Outside;
135 else if (distanceToPlane <= capsule.radius)
136 intersections |= (1 << i);
137 #endif
138 }
139
140 return (intersections == 0) ? Inside : Intersect;
141 }
142
143
144 #if 0
145 // See if the half space defined by the plane intersects the frustum. For the
146 // plane equation p(x, y, z) = ax + by + cz + d = 0, the halfspace is
147 // contains all points p(x, y, z) < 0.
148 Frustum::Aspect Frustum::testHalfSpace(const Planef& plane)
149 {
150 return Intersect;
151 }
152 #endif
153
154
transform(const Mat3f & m)155 void Frustum::transform(const Mat3f& m)
156 {
157 int nPlanes = infinite ? 5 : 6;
158 Mat3f invTranspose = m.inverse().transpose();
159
160 for (int i = 0; i < nPlanes; i++)
161 {
162 planes[i] = planes[i] * invTranspose;
163 float s = 1.0f / planes[i].normal.length();
164 planes[i].normal = planes[i].normal * s;
165 planes[i].d *= s;
166 }
167 }
168
169
transform(const Mat4f & m)170 void Frustum::transform(const Mat4f& m)
171 {
172 int nPlanes = infinite ? 5 : 6;
173 Mat4f invTranspose = m.inverse().transpose();
174
175 for (int i = 0; i < nPlanes; i++)
176 {
177 planes[i] = planes[i] * invTranspose;
178 float s = 1.0f / planes[i].normal.length();
179 planes[i].normal = planes[i].normal * s;
180 planes[i].d *= s;
181 }
182 }
183