我有一个相机对象，我把它放在网上阅读，处理向前和向后移动，左右扫视，甚至用鼠标环顾四周。但是当我向任何方向移动时，试着环顾四周它会跳到那个地方，但是当我不移动并环顾它的时候。
我希望有人可以帮我解决为什么我可以同时移动和环顾四周？
main.h
#include "SDL/SDL.h"
#include "SDL/SDL_opengl.h"
#include <cmath>
#define CAMERASPEED 0.03f // The Camera Speed
struct tVector3 // Extended 3D Vector Struct
{
tVector3() {} // Struct Constructor
tVector3 (float new_x, float new_y, float new_z) // Init Constructor
{ x = new_x; y = new_y; z = new_z; }
// overload + operator
tVector3 operator+(tVector3 vVector) {return tVector3(vVector.x+x, vVector.y+y, vVector.z+z);}
// overload - operator
tVector3 operator-(tVector3 vVector) {return tVector3(x-vVector.x, y-vVector.y, z-vVector.z);}
// overload * operator
tVector3 operator*(float number) {return tVector3(x*number, y*number, z*number);}
// overload / operator
tVector3 operator/(float number) {return tVector3(x/number, y/number, z/number);}
float x, y, z; // 3D vector coordinates
};
class CCamera
{
public:
tVector3 mPos;
tVector3 mView;
tVector3 mUp;
void Strafe_Camera(float speed);
void Move_Camera(float speed);
void Rotate_View(float speed);
void Position_Camera(float pos_x, float pos_y,float pos_z,
float view_x, float view_y, float view_z,
float up_x, float up_y, float up_z);
};
void Draw_Grid();
camera.cpp
#include "main.h"
void CCamera::Position_Camera(float pos_x, float pos_y, float pos_z,
float view_x, float view_y, float view_z,
float up_x, float up_y, float up_z)
{
mPos = tVector3(pos_x, pos_y, pos_z);
mView = tVector3(view_x, view_y, view_z);
mUp = tVector3(up_x, up_y, up_z);
}
void CCamera::Move_Camera(float speed)
{
tVector3 vVector = mView - mPos;
mPos.x = mPos.x + vVector.x * speed;
mPos.z = mPos.z + vVector.z * speed;
mView.x = mView.x + vVector.x * speed;
mView.z = mView.z + vVector.z * speed;
}
void CCamera::Strafe_Camera(float speed)
{
tVector3 vVector = mView - mPos;
tVector3 vOrthoVector;
vOrthoVector.x = -vVector.z;
vOrthoVector.z = vVector.x;
mPos.x = mPos.x + vOrthoVector.x * speed;
mPos.z = mPos.z + vOrthoVector.z * speed;
mView.x = mView.x + vOrthoVector.x * speed;
mView.z = mView.z + vOrthoVector.z * speed;
}
void CCamera::Rotate_View(float speed)
{
tVector3 vVector = mView - mPos;
tVector3 vOrthoVector;
vOrthoVector.x = -vVector.z;
vOrthoVector.z = vVector.x;
mView.z = (float)(mPos.z + sin(speed)*vVector.x + cos(speed)*vVector.z);
mView.x = (float)(mPos.x + cos(speed)*vVector.x - sin(speed)*vVector.z);
}
和mousemotion代码
void processEvents()
{
int mid_x = screen_width >> 1;
int mid_y = screen_height >> 1;
int mpx = event.motion.x;
int mpy = event.motion.y;
float angle_y = 0.0f;
float angle_z = 0.0f;
while(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_MOUSEMOTION:
if( (mpx == mid_x) && (mpy == mid_y) ) return;
// Get the direction from the mouse cursor, set a resonable maneuvering speed
angle_y = (float)( (mid_x - mpx) ) / 1000; //1000
angle_z = (float)( (mid_y - mpy) ) / 1000; //1000
// The higher the value is the faster the camera looks around.
objCamera.mView.y += angle_z * 2;
// limit the rotation around the x-axis
if((objCamera.mView.y - objCamera.mPos.y) > 8) objCamera.mView.y = objCamera.mPos.y + 8;
if((objCamera.mView.y - objCamera.mPos.y) <-8) objCamera.mView.y = objCamera.mPos.y - 8;
objCamera.Rotate_View(-angle_y);
SDL_WarpMouse(mid_x, mid_y);
break;
case SDL_KEYUP:
objKeyb.handleKeyboardEvent(event,true);
break;
case SDL_KEYDOWN:
objKeyb.handleKeyboardEvent(event,false);
break;
case SDL_QUIT:
quit = true;
break;
case SDL_VIDEORESIZE:
screen = SDL_SetVideoMode( event.resize.w, event.resize.h, screen_bpp, SDL_OPENGL | SDL_HWSURFACE | SDL_RESIZABLE | SDL_GL_DOUBLEBUFFER | SDL_HWPALETTE );
screen_width = event.resize.w;
screen_height = event.resize.h;
init_opengl();
std::cout << "Resized to width: " << event.resize.w << " height: " << event.resize.h << std::endl;
break;
default:
break;
}
}
}
答案 0 :(得分：3)
我不完全确定你在做什么。
就个人而言，我只想允许一个简单的4x4矩阵。任何实现都可以。要旋转你，简单地说，需要使用鼠标x和y的变化旋转作为euler输入，以围绕y轴和x轴旋转。互联网上有很多代码可供您使用。
其中一些矩阵库不会为您提供“MoveForward（）”函数。如果是这样的话，那么前进很容易。第三列（如果使用行主矩阵，则为行）是前向向量。提取它。将其标准化（无论如何都应该归一化，因此可能不需要此步骤）。将它乘以您希望向前移动的数量，然后将其添加到位置（第4列/行）。
现在这是奇怪的部分。视图矩阵是一种特殊类型的矩阵。上面的矩阵定义了视图空间。如果将当前模型矩阵乘以此矩阵，则无法获得预期的答案。因为您希望将其转换为相机位于原点。因此，您需要有效地撤消相机转换，以将内容重新定向到上面定义的视图。为此，您可以将模型矩阵乘以视图矩阵的逆。
现在，您在正确的视图空间中定义了一个对象。
这是我非常简单的相机类。它没有处理你描述的功能，但希望能给你一些关于如何设置类的想法（警告，我使用行专业，即DirectX风格，矩阵）。
BaseCamera.h：
#ifndef BASE_CAMERA_H_
#define BASE_CAMERA_H_
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
#include "Maths/Vector4.h"
#include "Maths/Matrix4x4.h"
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
class BaseCamera
{
protected:
bool mDirty;
MathsLib::Matrix4x4 mCameraMat;
MathsLib::Matrix4x4 mViewMat;
public:
BaseCamera();
BaseCamera( const BaseCamera& camera );
BaseCamera( const MathsLib::Vector4& vPos, const MathsLib::Vector4& vLookAt );
BaseCamera( const MathsLib::Matrix4x4& matCamera );
bool IsDirty() const;
void SetDirty();
MathsLib::Matrix4x4& GetOrientationMatrix();
const MathsLib::Matrix4x4& GetOrientationMatrix() const;
MathsLib::Matrix4x4& GetViewMatrix();
};
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
inline MathsLib::Matrix4x4& BaseCamera::GetOrientationMatrix()
{
return mCameraMat;
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
inline const MathsLib::Matrix4x4& BaseCamera::GetOrientationMatrix() const
{
return mCameraMat;
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
inline bool BaseCamera::IsDirty() const
{
return mDirty;
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
inline void BaseCamera::SetDirty()
{
mDirty = true;
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
#endif
BaseCamera.cpp：
#include "Render/stdafx.h"
#include "BaseCamera.h"
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
BaseCamera::BaseCamera() :
mDirty( true )
{
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
BaseCamera::BaseCamera( const BaseCamera& camera ) :
mDirty( camera.mDirty ),
mCameraMat( camera.mCameraMat ),
mViewMat( camera.mViewMat )
{
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
BaseCamera::BaseCamera( const MathsLib::Vector4& vPos, const MathsLib::Vector4& vLookAt ) :
mDirty( true )
{
MathsLib::Vector4 vDir = (vLookAt - vPos).Normalise();
MathsLib::Vector4 vLat = MathsLib::CrossProduct( MathsLib::Vector4( 0.0f, 1.0f, 0.0f ), vDir ).Normalise();
MathsLib::Vector4 vUp = MathsLib::CrossProduct( vDir, vLat );//.Normalise();
mCameraMat.Set( vLat, vUp, vDir, vPos );
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
BaseCamera::BaseCamera( const MathsLib::Matrix4x4& matCamera ) :
mDirty( true ),
mCameraMat( matCamera )
{
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
MathsLib::Matrix4x4& BaseCamera::GetViewMatrix()
{
if ( IsDirty() )
{
mViewMat = mCameraMat.Inverse();
mDirty = false;
}
return mViewMat;
}
/*+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+*/
答案 1 :(得分：1)
我同意Goz。如果要表示仿射变换（例如rotate + translate
），则需要使用homegenous 4x4 matrices假设row major representation，如果没有缩放或剪切，则您的4x4矩阵表示以下内容：
第0到第2行：本地坐标系的三个基矢量（即x，y，z）
第3行：来自原点的当前翻译
所以沿着你的局部x向量移动，正如Goz所说，因为你可以假设它是一个单位向量 如果没有比例/剪切，你只需将它乘以移动步骤（+ ve或-ve），然后将结果向量添加到矩阵的第4行 因此，举一个从原点开始的简单示例，将本地框架设置为世界框架，那么您的矩阵看起来就像这样
1 0 0 0＆lt; --- x单位向量
0 1 0 0＆lt; --- y单位矢量
0 0 1 0＆lt; --- z单位矢量
0 0 0 1＆lt; ---翻译矢量
就大多数游戏相机的工作方式而言，轴的映射方式如下：
x轴＆lt; =＆gt;相机底盘左/右
y轴＆lt; =＆gt;相机平移上/下
z轴＆lt; =＆gt;相机放大/缩小
因此，如果我旋转整个引用框架以查看新点LookAt然后Goz放入他的BaseCamera重载构造函数代码，则构建一个新的局部坐标系并将其设置为矩阵（全部{ {1}}通常设置矩阵的那四行，即VLat将是行0，vUp行1，vDir行2和vPos行3）
然后放大/缩小就会变成第3行=第2行*步骤
再次正如Goz所指出的那样，你需要将其转换回世界空间，这可以通过乘以视图矩阵的倒数来完成