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cylindricalLens.cxx
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1/**
2 * PANDA 3D SOFTWARE
3 * Copyright (c) Carnegie Mellon University. All rights reserved.
4 *
5 * All use of this software is subject to the terms of the revised BSD
6 * license. You should have received a copy of this license along
7 * with this source code in a file named "LICENSE."
8 *
9 * @file cylindricalLens.cxx
10 * @author drose
11 * @date 2001-12-12
12 */
13
14#include "cylindricalLens.h"
15#include "deg_2_rad.h"
16
17TypeHandle CylindricalLens::_type_handle;
18
19// This is the focal-length constant for fisheye lenses. See fisheyeLens.cxx.
20static const PN_stdfloat cylindrical_k = 60.0f;
21// focal_length = film_size * cylindrical_k fov;
22
23
24/**
25 * Allocates a new Lens just like this one.
26 */
27PT(Lens) CylindricalLens::
28make_copy() const {
29 return new CylindricalLens(*this);
30}
31
32/**
33 * Given a 2-d point in the range (-1,1) in both dimensions, where (0,0) is
34 * the center of the lens and (-1,-1) is the lower-left corner, compute the
35 * corresponding vector in space that maps to this point, if such a vector can
36 * be determined. The vector is returned by indicating the points on the near
37 * plane and far plane that both map to the indicated 2-d point.
38 *
39 * The z coordinate of the 2-d point is ignored.
40 *
41 * Returns true if the vector is defined, or false otherwise.
42 */
43bool CylindricalLens::
44do_extrude(const Lens::CData *lens_cdata,
45 const LPoint3 &point2d, LPoint3 &near_point, LPoint3 &far_point) const {
46 // Undo the shifting from film offsets, etc. This puts the point into the
47 // range [-film_size2, film_size2] in x and y.
48 LPoint3 f = point2d * do_get_film_mat_inv(lens_cdata);
49
50 PN_stdfloat focal_length = do_get_focal_length(lens_cdata);
51 PN_stdfloat angle = f[0] * cylindrical_k / focal_length;
52 PN_stdfloat sinAngle, cosAngle;
53 csincos(deg_2_rad(angle), &sinAngle, &cosAngle);
54
55 // Define a unit vector (well, a unit vector in the XY plane, at least) that
56 // represents the vector corresponding to this point.
57 LPoint3 v(sinAngle, cosAngle, f[1] / focal_length);
58
59 // And we'll need to account for the lens's rotations, etc. at the end of
60 // the day.
61 const LMatrix4 &lens_mat = do_get_lens_mat(lens_cdata);
62 const LMatrix4 &proj_inv_mat = do_get_projection_mat_inv(lens_cdata);
63
64 near_point = (v * do_get_near(lens_cdata)) * proj_inv_mat * lens_mat;
65 far_point = (v * do_get_far(lens_cdata)) * proj_inv_mat * lens_mat;
66 return true;
67}
68
69/**
70 * Given a 2-d point in the range (-1,1) in both dimensions, where (0,0) is
71 * the center of the lens and (-1,-1) is the lower-left corner, compute the
72 * vector that corresponds to the view direction. This will be parallel to
73 * the normal on the surface (the far plane) corresponding to the lens shape
74 * at this point.
75 *
76 * See the comment block on Lens::extrude_vec_impl() for a more in-depth
77 * comment on the meaning of this vector.
78 *
79 * The z coordinate of the 2-d point is ignored.
80 *
81 * Returns true if the vector is defined, or false otherwise.
82 */
83bool CylindricalLens::
84do_extrude_vec(const Lens::CData *lens_cdata, const LPoint3 &point2d, LVector3 &vec) const {
85 // Undo the shifting from film offsets, etc. This puts the point into the
86 // range [-film_size2, film_size2] in x and y.
87 LPoint3 f = point2d * do_get_film_mat_inv(lens_cdata);
88
89 PN_stdfloat focal_length = do_get_focal_length(lens_cdata);
90 PN_stdfloat angle = f[0] * cylindrical_k / focal_length;
91 PN_stdfloat sinAngle, cosAngle;
92 csincos(deg_2_rad(angle), &sinAngle, &cosAngle);
93
94 vec = LVector3(sinAngle, cosAngle, 0.0f) * do_get_projection_mat_inv(lens_cdata) * do_get_lens_mat(lens_cdata);
95
96 return true;
97}
98
99/**
100 * Given a 3-d point in space, determine the 2-d point this maps to, in the
101 * range (-1,1) in both dimensions, where (0,0) is the center of the lens and
102 * (-1,-1) is the lower-left corner.
103 *
104 * Some lens types also set the z coordinate of the 2-d point to a value in
105 * the range (-1, 1), where -1 represents a point on the near plane, and 1
106 * represents a point on the far plane.
107 *
108 * Returns true if the 3-d point is in front of the lens and within the
109 * viewing frustum (in which case point2d is filled in), or false otherwise.
110 */
111bool CylindricalLens::
112do_project(const Lens::CData *lens_cdata, const LPoint3 &point3d, LPoint3 &point2d) const {
113 // First, account for any rotations, etc. on the lens.
114 LPoint3 p = point3d * do_get_lens_mat_inv(lens_cdata) * do_get_projection_mat(lens_cdata);
115
116 // To compute the x position on the frame, we only need to consider the
117 // angle of the vector about the Z axis. Project the vector into the XY
118 // plane to do this.
119 LVector2 xy(p[0], p[1]);
120
121 // The perspective distance is the length of this vector in the XY plane.
122 PN_stdfloat pdist = xy.length();
123 if (pdist == 0.0f) {
124 point2d.set(0.0f, 0.0f, 0.0f);
125 return false;
126 }
127
128 PN_stdfloat focal_length = do_get_focal_length(lens_cdata);
129
130 // Compute the depth as a linear distance in the range 0 .. 1.
131 PN_stdfloat z = (pdist - do_get_near(lens_cdata)) / (do_get_far(lens_cdata) - do_get_near(lens_cdata));
132
133 point2d.set
134 (
135 // The x position is the angle about the Z axis.
136 rad_2_deg(catan2(xy[0], xy[1])) * focal_length / cylindrical_k,
137 // The y position is the Z height divided by the perspective distance.
138 p[2] * focal_length / pdist,
139 // Z is the distance scaled into the range -1 .. 1.
140 2.0 * z - 1.0
141 );
142
143 // Now we have to transform the point according to the film adjustments.
144 point2d = point2d * do_get_film_mat(lens_cdata);
145
146 return
147 point2d[0] >= -1.0f && point2d[0] <= 1.0f &&
148 point2d[1] >= -1.0f && point2d[1] <= 1.0f;
149}
150
151/**
152 * Given a field of view in degrees and a focal length, compute the
153 * correspdonding width (or height) on the film. If horiz is true, this is in
154 * the horizontal direction; otherwise, it is in the vertical direction (some
155 * lenses behave differently in each direction).
156 */
157PN_stdfloat CylindricalLens::
158fov_to_film(PN_stdfloat fov, PN_stdfloat focal_length, bool horiz) const {
159 if (horiz) {
160 return focal_length * fov / cylindrical_k;
161 } else {
162 return (ctan(deg_2_rad(fov * 0.5f)) * focal_length) * 2.0f;
163 }
164}
165
166/**
167 * Given a field of view in degrees and a width (or height) on the film,
168 * compute the focal length of the lens. If horiz is true, this is in the
169 * horizontal direction; otherwise, it is in the vertical direction (some
170 * lenses behave differently in each direction).
171 */
172PN_stdfloat CylindricalLens::
173fov_to_focal_length(PN_stdfloat fov, PN_stdfloat film_size, bool horiz) const {
174 if (horiz) {
175 return film_size * cylindrical_k / fov;
176 } else {
177 return film_size * 0.5f / ctan(deg_2_rad(fov * 0.5f));
178 }
179}
180
181/**
182 * Given a width (or height) on the film and a focal length, compute the field
183 * of view in degrees. If horiz is true, this is in the horizontal direction;
184 * otherwise, it is in the vertical direction (some lenses behave differently
185 * in each direction).
186 */
187PN_stdfloat CylindricalLens::
188film_to_fov(PN_stdfloat film_size, PN_stdfloat focal_length, bool horiz) const {
189 if (horiz) {
190 return film_size * cylindrical_k / focal_length;
191 } else {
192 return rad_2_deg(catan(film_size * 0.5f / focal_length)) * 2.0f;
193 }
194}
A cylindrical lens.
A base class for any number of different kinds of lenses, linear and otherwise.
Definition lens.h:41
TypeHandle is the identifier used to differentiate C++ class types.
Definition typeHandle.h:81
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.
PANDA 3D SOFTWARE Copyright (c) Carnegie Mellon University.