assimp/include/assimp/camera.h

227 lines
7.4 KiB
C

/*
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Open Asset Import Library (assimp)
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*/
/** @file camera.h
* @brief Defines the aiCamera data structure
*/
#pragma once
#ifndef AI_CAMERA_H_INC
#define AI_CAMERA_H_INC
#include "types.h"
#ifdef __cplusplus
extern "C" {
#endif
// ---------------------------------------------------------------------------
/** Helper structure to describe a virtual camera.
*
* Cameras have a representation in the node graph and can be animated.
* An important aspect is that the camera itself is also part of the
* scenegraph. This means, any values such as the look-at vector are not
* *absolute*, they're <b>relative</b> to the coordinate system defined
* by the node which corresponds to the camera. This allows for camera
* animations. For static cameras parameters like the 'look-at' or 'up' vectors
* are usually specified directly in aiCamera, but beware, they could also
* be encoded in the node transformation. The following (pseudo)code sample
* shows how to do it: <br><br>
* @code
* // Get the camera matrix for a camera at a specific time
* // if the node hierarchy for the camera does not contain
* // at least one animated node this is a static computation
* get-camera-matrix (node sceneRoot, camera cam) : matrix
* {
* node cnd = find-node-for-camera(cam)
* matrix cmt = identity()
*
* // as usual - get the absolute camera transformation for this frame
* for each node nd in hierarchy from sceneRoot to cnd
* matrix cur
* if (is-animated(nd))
* cur = eval-animation(nd)
* else cur = nd->mTransformation;
* cmt = mult-matrices( cmt, cur )
* end for
*
* // now multiply with the camera's own local transform
* cam = mult-matrices (cam, get-camera-matrix(cmt) )
* }
* @endcode
*
* @note some file formats (such as 3DS, ASE) export a "target point" -
* the point the camera is looking at (it can even be animated). Assimp
* writes the target point as a subnode of the camera's main node,
* called "<camName>.Target". However this is just additional information
* then the transformation tracks of the camera main node make the
* camera already look in the right direction.
*
*/
struct aiCamera
{
/** The name of the camera.
*
* There must be a node in the scenegraph with the same name.
* This node specifies the position of the camera in the scene
* hierarchy and can be animated.
*/
C_STRUCT aiString mName;
/** Position of the camera relative to the coordinate space
* defined by the corresponding node.
*
* The default value is 0|0|0.
*/
C_STRUCT aiVector3D mPosition;
/** 'Up' - vector of the camera coordinate system relative to
* the coordinate space defined by the corresponding node.
*
* The 'right' vector of the camera coordinate system is
* the cross product of the up and lookAt vectors.
* The default value is 0|1|0. The vector
* may be normalized, but it needn't.
*/
C_STRUCT aiVector3D mUp;
/** 'LookAt' - vector of the camera coordinate system relative to
* the coordinate space defined by the corresponding node.
*
* This is the viewing direction of the user.
* The default value is 0|0|1. The vector
* may be normalized, but it needn't.
*/
C_STRUCT aiVector3D mLookAt;
/** Half horizontal field of view angle, in radians.
*
* The field of view angle is the angle between the center
* line of the screen and the left or right border.
* The default value is 1/4PI.
*/
float mHorizontalFOV;
/** Distance of the near clipping plane from the camera.
*
* The value may not be 0.f (for arithmetic reasons to prevent
* a division through zero). The default value is 0.1f.
*/
float mClipPlaneNear;
/** Distance of the far clipping plane from the camera.
*
* The far clipping plane must, of course, be further away than the
* near clipping plane. The default value is 1000.f. The ratio
* between the near and the far plane should not be too
* large (between 1000-10000 should be ok) to avoid floating-point
* inaccuracies which could lead to z-fighting.
*/
float mClipPlaneFar;
/** Screen aspect ratio.
*
* This is the ration between the width and the height of the
* screen. Typical values are 4/3, 1/2 or 1/1. This value is
* 0 if the aspect ratio is not defined in the source file.
* 0 is also the default value.
*/
float mAspect;
#ifdef __cplusplus
aiCamera() AI_NO_EXCEPT
: mUp (0.f,1.f,0.f)
, mLookAt (0.f,0.f,1.f)
, mHorizontalFOV (0.25f * (float)AI_MATH_PI)
, mClipPlaneNear (0.1f)
, mClipPlaneFar (1000.f)
, mAspect (0.f)
{}
/** @brief Get a *right-handed* camera matrix from me
* @param out Camera matrix to be filled
*/
void GetCameraMatrix (aiMatrix4x4& out) const
{
/** todo: test ... should work, but i'm not absolutely sure */
/** We don't know whether these vectors are already normalized ...*/
aiVector3D zaxis = mLookAt; zaxis.Normalize();
aiVector3D yaxis = mUp; yaxis.Normalize();
aiVector3D xaxis = mUp^mLookAt; xaxis.Normalize();
out.a4 = -(xaxis * mPosition);
out.b4 = -(yaxis * mPosition);
out.c4 = -(zaxis * mPosition);
out.a1 = xaxis.x;
out.a2 = xaxis.y;
out.a3 = xaxis.z;
out.b1 = yaxis.x;
out.b2 = yaxis.y;
out.b3 = yaxis.z;
out.c1 = zaxis.x;
out.c2 = zaxis.y;
out.c3 = zaxis.z;
out.d1 = out.d2 = out.d3 = 0.f;
out.d4 = 1.f;
}
#endif
};
#ifdef __cplusplus
}
#endif
#endif // AI_CAMERA_H_INC