Panda3D
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00001 // Filename: fisheyeLens.cxx 00002 // Created by: drose (12Dec01) 00003 // 00004 //////////////////////////////////////////////////////////////////// 00005 // 00006 // PANDA 3D SOFTWARE 00007 // Copyright (c) Carnegie Mellon University. All rights reserved. 00008 // 00009 // All use of this software is subject to the terms of the revised BSD 00010 // license. You should have received a copy of this license along 00011 // with this source code in a file named "LICENSE." 00012 // 00013 //////////////////////////////////////////////////////////////////// 00014 00015 #include "fisheyeLens.h" 00016 #include "deg_2_rad.h" 00017 00018 TypeHandle FisheyeLens::_type_handle; 00019 00020 // This is the focal-length constant for fisheye lenses. The focal 00021 // length of a fisheye lens relates to its fov by the equation: 00022 00023 // w = Fd/k 00024 00025 // Where w is the width of the negative, F is the focal length, and d 00026 // is the total field of view in degrees. 00027 00028 // k is chosen to make the focal lengths for a fisheye lens roughly 00029 // correspond to the equivalent field of view for a conventional, 00030 // perspective lens. It was determined empirically by simple 00031 // examination of a couple of actual lenses for 35mm film. I don't 00032 // know how well this extends to other lenses and other negative 00033 // sizes. 00034 00035 static const float fisheye_k = 60.0f; 00036 // focal_length = film_size * fisheye_k / fov; 00037 00038 00039 //////////////////////////////////////////////////////////////////// 00040 // Function: FisheyeLens::make_copy 00041 // Access: Public, Virtual 00042 // Description: Allocates a new Lens just like this one. 00043 //////////////////////////////////////////////////////////////////// 00044 PT(Lens) FisheyeLens:: 00045 make_copy() const { 00046 return new FisheyeLens(*this); 00047 } 00048 00049 //////////////////////////////////////////////////////////////////// 00050 // Function: FisheyeLens::extrude_impl 00051 // Access: Protected, Virtual 00052 // Description: Given a 2-d point in the range (-1,1) in both 00053 // dimensions, where (0,0) is the center of the 00054 // lens and (-1,-1) is the lower-left corner, 00055 // compute the corresponding vector in space that maps 00056 // to this point, if such a vector can be determined. 00057 // The vector is returned by indicating the points on 00058 // the near plane and far plane that both map to the 00059 // indicated 2-d point. 00060 // 00061 // The z coordinate of the 2-d point is ignored. 00062 // 00063 // Returns true if the vector is defined, or false 00064 // otherwise. 00065 //////////////////////////////////////////////////////////////////// 00066 bool FisheyeLens:: 00067 extrude_impl(const LPoint3f &point2d, LPoint3f &near_point, LPoint3f &far_point) const { 00068 // Undo the shifting from film offsets, etc. This puts the point 00069 // into the range [-film_size/2, film_size/2] in x and y. 00070 LPoint3f f = point2d * get_film_mat_inv(); 00071 00072 // First, get the vector from the center of the film to the point, 00073 // and normalize it. 00074 LVector2f v2(f[0], f[1]); 00075 00076 LPoint3f v; 00077 00078 float r = v2.length(); 00079 if (r == 0.0f) { 00080 // Special case: directly forward. 00081 v.set(0.0f, 1.0f, 0.0f); 00082 00083 } else { 00084 v2 /= r; 00085 00086 // Now get the point r units around the circle in the YZ plane. 00087 float focal_length = get_focal_length(); 00088 float angle = r * fisheye_k / focal_length; 00089 float sinAngle, cosAngle; 00090 csincos(deg_2_rad(angle), &sinAngle, &cosAngle); 00091 00092 LVector3f p(0.0, cosAngle, sinAngle); 00093 00094 // And rotate this point around the Y axis. 00095 v.set(p[0]*v2[1] + p[2]*v2[0], 00096 p[1], 00097 p[2]*v2[1] - p[0]*v2[0]); 00098 } 00099 00100 // And we'll need to account for the lens's rotations, etc. at the 00101 // end of the day. 00102 const LMatrix4f &lens_mat = get_lens_mat(); 00103 00104 near_point = (v * get_near()) * lens_mat; 00105 far_point = (v * get_far()) * lens_mat; 00106 return true; 00107 } 00108 00109 //////////////////////////////////////////////////////////////////// 00110 // Function: FisheyeLens::extrude_vec_impl 00111 // Access: Protected, Virtual 00112 // Description: Given a 2-d point in the range (-1,1) in both 00113 // dimensions, where (0,0) is the center of the 00114 // lens and (-1,-1) is the lower-left corner, 00115 // compute the vector that corresponds to the view 00116 // direction. This will be parallel to the normal on 00117 // the surface (the far plane) corresponding to the lens 00118 // shape at this point. 00119 // 00120 // See the comment block on Lens::extrude_vec_impl() for 00121 // a more in-depth comment on the meaning of this 00122 // vector. 00123 // 00124 // The z coordinate of the 2-d point is ignored. 00125 // 00126 // Returns true if the vector is defined, or false 00127 // otherwise. 00128 //////////////////////////////////////////////////////////////////// 00129 bool FisheyeLens:: 00130 extrude_vec_impl(const LPoint3f &point2d, LVector3f &vec) const { 00131 LPoint3f near_point, far_point; 00132 if (!extrude_impl(point2d, near_point, far_point)) { 00133 return false; 00134 } 00135 00136 vec = far_point - near_point; 00137 00138 return true; 00139 } 00140 00141 //////////////////////////////////////////////////////////////////// 00142 // Function: FisheyeLens::project_impl 00143 // Access: Protected, Virtual 00144 // Description: Given a 3-d point in space, determine the 2-d point 00145 // this maps to, in the range (-1,1) in both dimensions, 00146 // where (0,0) is the center of the lens and 00147 // (-1,-1) is the lower-left corner. 00148 // 00149 // Some lens types also set the z coordinate of the 2-d 00150 // point to a value in the range (-1, 1), where 1 00151 // represents a point on the near plane, and -1 00152 // represents a point on the far plane. 00153 // 00154 // Returns true if the 3-d point is in front of the lens 00155 // and within the viewing frustum (in which case point2d 00156 // is filled in), or false otherwise. 00157 //////////////////////////////////////////////////////////////////// 00158 bool FisheyeLens:: 00159 project_impl(const LPoint3f &point3d, LPoint3f &point2d) const { 00160 // First, account for any rotations, etc. on the lens. 00161 LVector3f v2 = point3d * get_lens_mat_inv(); 00162 00163 // A fisheye lens projection has the property that the distance from 00164 // the center point to any other point on the projection is 00165 // proportional to the actual distance on the sphere along the great 00166 // circle. Also, the angle to the point on the projection is equal 00167 // to the angle to the point on the sphere. 00168 00169 // First, get the straight-line distance from the lens, and use it 00170 // to normalize the vector. 00171 float dist = v2.length(); 00172 v2 /= dist; 00173 00174 // Now, project the point into the XZ plane and measure its angle 00175 // to the Z axis. This is the same angle it will have to the 00176 // vertical axis on the film. 00177 LVector2f y(v2[0], v2[2]); 00178 y.normalize(); 00179 00180 if (y == LVector2f(0.0f, 0.0f)) { 00181 // Special case. This point is either directly ahead or directly 00182 // behind. 00183 point2d.set(0.0f, 0.0f, 00184 (get_near() - dist) / (get_far() - get_near())); 00185 return v2[1] >= 0.0f; 00186 } 00187 00188 // Now bring the vector into the YZ plane by rotating about the Y 00189 // axis. 00190 LVector2f x(v2[1], v2[0]*y[0]+v2[2]*y[1]); 00191 00192 // Now the angle of x to the forward vector represents the distance 00193 // along the great circle to the point. 00194 float r = 90.0f - rad_2_deg(catan2(x[0], x[1])); 00195 00196 float focal_length = get_focal_length(); 00197 float factor = r * focal_length / fisheye_k; 00198 00199 point2d.set 00200 (y[0] * factor, 00201 y[1] * factor, 00202 // Z is the distance scaled into the range (1, -1). 00203 (get_near() - dist) / (get_far() - get_near()) 00204 ); 00205 00206 // Now we have to transform the point according to the film 00207 // adjustments. 00208 point2d = point2d * get_film_mat(); 00209 00210 return 00211 point2d[0] >= -1.0f && point2d[0] <= 1.0f && 00212 point2d[1] >= -1.0f && point2d[1] <= 1.0f; 00213 } 00214 00215 //////////////////////////////////////////////////////////////////// 00216 // Function: FisheyeLens::fov_to_film 00217 // Access: Protected, Virtual 00218 // Description: Given a field of view in degrees and a focal length, 00219 // compute the correspdonding width (or height) on the 00220 // film. If horiz is true, this is in the horizontal 00221 // direction; otherwise, it is in the vertical direction 00222 // (some lenses behave differently in each direction). 00223 //////////////////////////////////////////////////////////////////// 00224 float FisheyeLens:: 00225 fov_to_film(float fov, float focal_length, bool) const { 00226 return focal_length * fov / fisheye_k; 00227 } 00228 00229 //////////////////////////////////////////////////////////////////// 00230 // Function: FisheyeLens::fov_to_focal_length 00231 // Access: Protected, Virtual 00232 // Description: Given a field of view in degrees and a width (or 00233 // height) on the film, compute the focal length of the 00234 // lens. If horiz is true, this is in the horizontal 00235 // direction; otherwise, it is in the vertical direction 00236 // (some lenses behave differently in each direction). 00237 //////////////////////////////////////////////////////////////////// 00238 float FisheyeLens:: 00239 fov_to_focal_length(float fov, float film_size, bool) const { 00240 return film_size * fisheye_k / fov; 00241 } 00242 00243 //////////////////////////////////////////////////////////////////// 00244 // Function: FisheyeLens::film_to_fov 00245 // Access: Protected, Virtual 00246 // Description: Given a width (or height) on the film and a focal 00247 // length, compute the field of view in degrees. If 00248 // horiz is true, this is in the horizontal direction; 00249 // otherwise, it is in the vertical direction (some 00250 // lenses behave differently in each direction). 00251 //////////////////////////////////////////////////////////////////// 00252 float FisheyeLens:: 00253 film_to_fov(float film_size, float focal_length, bool) const { 00254 return film_size * fisheye_k / focal_length; 00255 } 00256