OpenGL(在Qt中）-旋转问题
OpenGL(in Qt ) - problem in rotation
我在openGL中做了一个简单的代码。你必须选择一张图片，就这样。现在你可以使用这些键进行旋转
- a、 s->绕x轴旋转
- d、 f->绕y轴旋转
- b、 n->绕z轴旋转
问题是z轴旋转始终可以正常工作。但是，x，y的旋转并不总是正确的。
测试：按下任何（一个）按钮，你可以看到一个轴根本没有移动，另一个轴正在移动。你可以检查这三个轴。但过了一段时间，即使你试图绕x轴旋转物体，你也可以看到所有三个轴都在移动。奇怪的是，绕z轴旋转总是能正常工作。只有另外两个让人头疼。
这是"main.cpp"
#include <QApplication>
#include <QFileDialog>
#include <QHBoxLayout>
#include <QKeyEvent>
#include <QMessageBox>
#include <QPainter>
#include <QTextStream>
#include <QtOpenGL/QGLWidget>
#include <QVector3D>
#include <QWidget>
class MyMessageBox:public QMessageBox
{
public:
MyMessageBox(std::string message,QWidget *parent=0):QMessageBox(QMessageBox::NoIcon,QString("ErrorMessage"),QString(message.c_str()),QMessageBox::Ok,parent,Qt::Widget)
{
}
};
class MyOpenGL:public QGLWidget
{
double x_Rot;
double y_Rot;
double z_Rot;
QVector<GLuint *> textures; // it does nothing. It got added just for the sake of the program run
QVector<QImage> openGL_Images;
public:
MyOpenGL(QWidget * parent);
~MyOpenGL();
void initializeGL();
void resizeGL(int w, int h);
void paintGL();
void drawCube(QPoint upper_Left_Point,int length,int width,int height,QVector<GLuint *> textures);
void drawAxis();
QVector3D get_In_OpenGL_Coordinates(QPoint qwidget_Point);
void keyPressEvent(QKeyEvent * event);
void mousePressEvent(QMouseEvent * event);
};
MyOpenGL::MyOpenGL(QWidget *parent):QGLWidget(QGLFormat(QGL::SampleBuffers),parent)
{
setAutoFillBackground(false);
}
MyOpenGL::~MyOpenGL()
{
}
void MyOpenGL::initializeGL()
{
//textures.push_back(new GLuint);
//textures.push_back(new GLuint);
QString fileName=QFileDialog::getOpenFileName();
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
openGL_Images.push_back(convertToGLFormat(QImage(fileName).scaled(QSize(256,256))));
//glGenTextures(1,textures[0]);
//glBindTexture(GL_TEXTURE_2D,*textures[0]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glEnable(GL_TEXTURE_2D);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f,0.0f,0.0f,0.0f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);
}
void MyOpenGL::resizeGL(int w, int h)
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(45,0,w,h);
gluPerspective(45.0f,((double)width())/height(),1.0f,100.0f);
//gluOrtho2D(-10.0f,10.0f,-10.0f,10.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
paintGL();
}
void MyOpenGL::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glTranslatef(0.0,0.0,-10.0);
glRotatef(x_Rot,1.0f,0.0f,0.0f);
glRotatef(y_Rot,0.0f,1.0f,0.0f);
glRotatef(z_Rot,0.0f,0.0f,1.0f);
drawAxis();
//drawCube(QPoint(0,0),1,1,1,textures);
}
void MyOpenGL::drawCube(QPoint upper_Left_Back_Point, int length, int width, int height,QVector<GLuint *> textures1)
{
//glGenTextures(1,textures[0]);
//glBindTexture(GL_TEXTURE_2D,*textures[0]);
QVector3D starting_Point = get_In_OpenGL_Coordinates(upper_Left_Back_Point);
double x=starting_Point.x();
double y=starting_Point.y();
double z=starting_Point.z();
//glGenTextures(1,textures[0]);
//glBindTexture(GL_TEXTURE_2D,*textures[0]);
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[0].width(),openGL_Images[0].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[0].bits());
glBegin(GL_QUADS);
// glColor3f(1.0f,0.0f,0.0f);
glTexCoord2f(0,1);glVertex3f(x-width,y+height,z-length);
glTexCoord2f(1,1);glVertex3f(x+width,y+height,z-length);
glTexCoord2f(1,0);glVertex3f(x+width,y+height,z+length);
glTexCoord2f(0,0);glVertex3f(x-width,y+height,z+length);
glEnd();
//glGenTextures(1,textures[1]);
//glBindTexture(GL_TEXTURE_2D,*textures[1]);
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[1].width(),openGL_Images[1].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[1].bits());
glBegin(GL_QUADS);
//glColor3f(0.0f,1.0f,0.0f);
glTexCoord2f(0,1);glVertex3f(x+width,y+height,z-length);
glTexCoord2f(1,1);glVertex3f(x+width,y-height,z-length);
glTexCoord2f(1,0);glVertex3f(x+width,y-height,z+length);
glTexCoord2f(0,0);glVertex3f(x+width,y+height,z+length);
glEnd();
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[2].width(),openGL_Images[2].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[2].bits());
glBegin(GL_QUADS);
//glColor3f(0.0f,0.0f,1.0f);
glTexCoord2f(0,1);glVertex3f(x+width,y-height,z-length);
glTexCoord2f(1,1);glVertex3f(x-width,y-height,z-length);
glTexCoord2f(1,0);glVertex3f(x-width,y-height,z+length);
glTexCoord2f(0,0);glVertex3f(x+width,y-height,z+length);
glEnd();
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[3].width(),openGL_Images[3].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[3].bits());
glBegin(GL_QUADS);
//glColor3f(1.0f,1.0f,0.0f);
glTexCoord2f(0,1);glVertex3f(x-width,y+height,z+length);
glTexCoord2f(1,1);glVertex3f(x-width,y+height,z-length);
glTexCoord2f(1,0);glVertex3f(x-width,y-height,z-length);
glTexCoord2f(0,0);glVertex3f(x-width,y-height,z+length);
glEnd();
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[4].width(),openGL_Images[4].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[4].bits());
glBegin(GL_QUADS);
//glColor3f(1.0f,0.0f,1.0f);
glTexCoord2f(0,1);glVertex3f(x-width,y+height,z-length);
glTexCoord2f(1,1);glVertex3f(x+width,y+height,z-length);
glTexCoord2f(1,0);glVertex3f(x+width,y-height,z-length);
glTexCoord2f(0,0);glVertex3f(x-width,y-height,z-length);
glEnd();
glTexImage2D(GL_TEXTURE_2D,0,3,openGL_Images[5].width(),openGL_Images[5].height(),0,GL_RGBA,GL_UNSIGNED_BYTE,openGL_Images[5].bits());
glBegin(GL_QUADS);
//glColor3f(0,1,1);
glTexCoord2f(0,1);glVertex3f(x-width,y+height,z+length);
glTexCoord2f(1,1);glVertex3f(x+width,y+height,z+length);
glTexCoord2f(1,0);glVertex3f(x+width,y-height,z+length);
glTexCoord2f(0,0);glVertex3f(x-width,y-height,z+length);
glEnd();
}
void MyOpenGL::drawAxis()
{
//int length = 1;
//int height = 1;
//int width = 1;
//int x = 0;
//int y=0;
//int z = 0;
glBegin(GL_LINES);
glColor3f(1,0,0);
glVertex3f(0,0,0);
glVertex3f(3,0,0);
glColor3f(0,1,0);
glVertex3f(0,0,0);
glVertex3f(0,3,0);
glColor3f(0,0,1);
glVertex3f(0,0,0);
glVertex3f(0,0,3);
//glVertex3f(x-width,y+height,z+length);
//glVertex3f(x+width,y+height,z+length);
//glVertex3f(x+width,y-height,z+length);
//glVertex3f(x-width,y-height,z+length);
glEnd();
}
QVector3D MyOpenGL::get_In_OpenGL_Coordinates(QPoint qwidget_Point)
{
return QVector3D(0,0,0);
}
void MyOpenGL::keyPressEvent(QKeyEvent * event)
{
switch(event->key())
{
case Qt::Key_A:
x_Rot-=5;
break;
case Qt::Key_S:
x_Rot+=5;
break;
case Qt::Key_D:
y_Rot+=5;
break;
case Qt::Key_F:
y_Rot-=5;
break;
case Qt::Key_B:
z_Rot+=5;
break;
case Qt::Key_N:
z_Rot-=5;
break;
default:
break;
}
updateGL();
}
void MyOpenGL::mousePressEvent(QMouseEvent *event)
{
double x = event->pos().x();
double y = event->pos().y();
double z=-1;
glReadPixels(x,y,1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&z);
double projection[16];
glGetDoublev(GL_PROJECTION_MATRIX,projection);
double modelView[16];
glGetDoublev(GL_MODELVIEW_MATRIX,modelView);
int viewPort[4];
glGetIntegerv(GL_VIEWPORT,viewPort);
double x_Gl;
double y_Gl;
double z_Gl;
gluUnProject(x,y,z,modelView,projection,viewPort,&x_Gl,&y_Gl,&z_Gl);
QString ss;
QTextStream ss_Text(&ss);
ss_Text << x_Gl << " " << y_Gl << " " << z_Gl ;
MyMessageBox mm(ss.toStdString());
mm.exec();
}
int main(int argc,char * argv[])
{
QApplication app(argc,argv);
MyOpenGL * f = new MyOpenGL(NULL);
f->show();
return app.exec();
}
这里是.pro文件
SOURCES +=
main.cpp
QT += opengl
有人请帮我摆脱困境。
首先对您的代码进行一些观察：
- 在哪里初始化x_Rot、y_Rot和z_Rot？我不知道这是怎么回事
接下来，一些更一般的评论：
从技术上讲，你现在所做的是围绕x、y和z旋转。如果你想做其他事情，比如每次按下按钮都要增量旋转，那么你需要仔细考虑你要做什么。一种方法是在OpenGL中增量应用旋转矩阵。另一种可能性是在客户端上存储四元数/矩阵，然后每帧重置视图变换。还有一种可能性是剔除一堆trig，并计算每次旋转的x/y/z角度的正确偏差（不推荐）。一旦你明白了你真正想做的是什么，你就可以做这些事情中的任何一件，甚至更多。要做到这一点，你必须读一点（对不起，数学就是这样运作的）。作为一个起点，这里有一些基本的wiki页面可以帮助你开始：
http://en.wikipedia.org/wiki/Rotation_representation_%28mathematics%29
http://en.wikipedia.org/wiki/Rotation_matrix
http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation
您的问题似乎是Gimbal Lock
使用四元数是处理这个问题最简单的方法之一。
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