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41
42/** @file camera.h
43 * @brief Defines the aiCamera data structure
44 */
45
46#pragma once
47#ifndef AI_CAMERA_H_INC
48#define AI_CAMERA_H_INC
49
50#include "types.h"
51
52#ifdef __cplusplus
53extern "C" {
54#endif
55
56// ---------------------------------------------------------------------------
57/** Helper structure to describe a virtual camera.
58 *
59 * Cameras have a representation in the node graph and can be animated.
60 * An important aspect is that the camera itself is also part of the
61 * scene-graph. This means, any values such as the look-at vector are not
62 * *absolute*, they're <b>relative</b> to the coordinate system defined
63 * by the node which corresponds to the camera. This allows for camera
64 * animations. For static cameras parameters like the 'look-at' or 'up' vectors
65 * are usually specified directly in aiCamera, but beware, they could also
66 * be encoded in the node transformation. The following (pseudo)code sample
67 * shows how to do it: <br><br>
68 * @code
69 * // Get the camera matrix for a camera at a specific time
70 * // if the node hierarchy for the camera does not contain
71 * // at least one animated node this is a static computation
72 * get-camera-matrix (node sceneRoot, camera cam) : matrix
73 * {
74 * node cnd = find-node-for-camera(cam)
75 * matrix cmt = identity()
76 *
77 * // as usual - get the absolute camera transformation for this frame
78 * for each node nd in hierarchy from sceneRoot to cnd
79 * matrix cur
80 * if (is-animated(nd))
81 * cur = eval-animation(nd)
82 * else cur = nd->mTransformation;
83 * cmt = mult-matrices( cmt, cur )
84 * end for
85 *
86 * // now multiply with the camera's own local transform
87 * cam = mult-matrices (cam, get-camera-matrix(cmt) )
88 * }
89 * @endcode
90 *
91 * @note some file formats (such as 3DS, ASE) export a "target point" -
92 * the point the camera is looking at (it can even be animated). Assimp
93 * writes the target point as a subnode of the camera's main node,
94 * called "<camName>.Target". However this is just additional information
95 * then the transformation tracks of the camera main node make the
96 * camera already look in the right direction.
97 *
98*/
99struct aiCamera
100{
101 /** The name of the camera.
102 *
103 * There must be a node in the scenegraph with the same name.
104 * This node specifies the position of the camera in the scene
105 * hierarchy and can be animated.
106 */
107 C_STRUCT aiString mName;
108
109 /** Position of the camera relative to the coordinate space
110 * defined by the corresponding node.
111 *
112 * The default value is 0|0|0.
113 */
114 C_STRUCT aiVector3D mPosition;
115
116 /** 'Up' - vector of the camera coordinate system relative to
117 * the coordinate space defined by the corresponding node.
118 *
119 * The 'right' vector of the camera coordinate system is
120 * the cross product of the up and lookAt vectors.
121 * The default value is 0|1|0. The vector
122 * may be normalized, but it needn't.
123 */
124 C_STRUCT aiVector3D mUp;
125
126
127 /** 'LookAt' - vector of the camera coordinate system relative to
128 * the coordinate space defined by the corresponding node.
129 *
130 * This is the viewing direction of the user.
131 * The default value is 0|0|1. The vector
132 * may be normalized, but it needn't.
133 */
134 C_STRUCT aiVector3D mLookAt;
135
136 /** Half horizontal field of view angle, in radians.
137 *
138 * The field of view angle is the angle between the center
139 * line of the screen and the left or right border.
140 * The default value is 1/4PI.
141 */
142 float mHorizontalFOV;
143
144 /** Distance of the near clipping plane from the camera.
145 *
146 * The value may not be 0.f (for arithmetic reasons to prevent
147 * a division through zero). The default value is 0.1f.
148 */
149 float mClipPlaneNear;
150
151 /** Distance of the far clipping plane from the camera.
152 *
153 * The far clipping plane must, of course, be further away than the
154 * near clipping plane. The default value is 1000.f. The ratio
155 * between the near and the far plane should not be too
156 * large (between 1000-10000 should be ok) to avoid floating-point
157 * inaccuracies which could lead to z-fighting.
158 */
159 float mClipPlaneFar;
160
161 /** Screen aspect ratio.
162 *
163 * This is the ration between the width and the height of the
164 * screen. Typical values are 4/3, 1/2 or 1/1. This value is
165 * 0 if the aspect ratio is not defined in the source file.
166 * 0 is also the default value.
167 */
168 float mAspect;
169
170#ifdef __cplusplus
171
172 aiCamera() AI_NO_EXCEPT
173 : mUp (0.f,1.f,0.f)
174 , mLookAt (0.f,0.f,1.f)
175 , mHorizontalFOV (0.25f * (float)AI_MATH_PI)
176 , mClipPlaneNear (0.1f)
177 , mClipPlaneFar (1000.f)
178 , mAspect (0.f)
179 {}
180
181 /** @brief Get a *right-handed* camera matrix from me
182 * @param out Camera matrix to be filled
183 */
184 void GetCameraMatrix (aiMatrix4x4& out) const
185 {
186 /** todo: test ... should work, but i'm not absolutely sure */
187
188 /** We don't know whether these vectors are already normalized ...*/
189 aiVector3D zaxis = mLookAt; zaxis.Normalize();
190 aiVector3D yaxis = mUp; yaxis.Normalize();
191 aiVector3D xaxis = mUp^mLookAt; xaxis.Normalize();
192
193 out.a4 = -(xaxis * mPosition);
194 out.b4 = -(yaxis * mPosition);
195 out.c4 = -(zaxis * mPosition);
196
197 out.a1 = xaxis.x;
198 out.a2 = xaxis.y;
199 out.a3 = xaxis.z;
200
201 out.b1 = yaxis.x;
202 out.b2 = yaxis.y;
203 out.b3 = yaxis.z;
204
205 out.c1 = zaxis.x;
206 out.c2 = zaxis.y;
207 out.c3 = zaxis.z;
208
209 out.d1 = out.d2 = out.d3 = 0.f;
210 out.d4 = 1.f;
211 }
212
213#endif
214};
215
216
217#ifdef __cplusplus
218}
219#endif
220
221#endif // AI_CAMERA_H_INC
222

source code of qt3d/src/3rdparty/assimp/src/include/assimp/camera.h