之前使用VS+glut實現了gluUnProject使用例子，用於渲染管道的逆過程，將屏幕坐標轉換為opengl三維坐標，本文將嘗試使用QT來實現。
代碼如下：
main.cpp
|
1
2 3 4 5 6 7 8 9 10 11 12 13 14 |
#include
"GLWidget.h"
#include <QApplication> int main( int argc, char *argv[]) { QApplication a(argc, argv); GLWidget glw; glw.resize( 640 , 480 ); glw.setWindowTitle( "gluUnProject Demo" ); glw.show(); return a.exec(); } |
GLWidget.h
|
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 |
#ifndef
GLWIDGET_H #define GLWIDGET_H #include <QGLWidget> class GLWidget : public QGLWidget { Q_OBJECT public : GLWidget(QWidget *parent = 0 ); ~GLWidget(); protected : virtual void initializeGL(); virtual void resizeGL( int w, int h); virtual void paintGL(); virtual void mousePressEvent(QMouseEvent *event); private : void draw(); void DrawFloor(); void DrawAxis(); GLdouble objx; GLdouble objy; GLdouble objz; }; #endif // GLWIDGET_H |
GLWidget.cpp
|
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 |
#include
"GLWidget.h"
#include <QMouseEvent> #include <GL/glu.h> #include <QDebug> static const qint32 s_Scale = 8 ; GLWidget::GLWidget(QWidget *parent) : QGLWidget(parent) { objx = 0 . 0 ; objy = 0 . 0 ; objz = 0 . 0 ; } GLWidget::~GLWidget() { } void GLWidget::initializeGL() { glClearColor( 0 . 0 , 0 . 0 , 0 . 0 , 0 . 0 ); glClearDepth( 1 . 0 ); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); } void GLWidget::resizeGL( int w, int h) { int viewport[ 4 ]; glViewport( 0 , 0 , w, h ); glGetIntegerv( GL_VIEWPORT, viewport ); glMatrixMode( GL_PROJECTION ); glLoadIdentity( ); gluPerspective( 45 , 1 . 33 , 0 . 1 , 400 ); double projection[ 16 ]; glGetDoublev( GL_PROJECTION_MATRIX, projection ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity( ); gluLookAt( 0 , 10 , 10 , 0 , 0 , 0 , 0 , 1 , 0 ); } void GLWidget::paintGL() { glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT ); //The big gray floor like polygon glBegin( GL_POLYGON ); glColor3f( 0 . 5 , 0 . 5 , 0 . 5 ); glVertex3f( - 10 , 0 , 10 ); glVertex3f( - 10 , 0 , - 10 ); glVertex3f( 10 , 0 , - 10 ); glVertex3f( 10 , 0 , 10 ); glEnd( ); //DrawFloor(); DrawAxis(); //The red cube to be drawn at clicked position glPushMatrix( ); glTranslatef(objx, objy, objz ); draw(); double modelview[ 16 ]; glGetDoublev( GL_MODELVIEW_MATRIX, modelview ); glPopMatrix( ); } void GLWidget::mousePressEvent(QMouseEvent *event) { updateGL(); double modelview[ 16 ], projection[ 16 ]; int viewport[ 4 ]; float x = event->pos().rx(); float y = event->pos().ry(); GLfloat z = 0 ; double winx, winy, winz; qDebug( "Window coords are (%d, %d)\n" , x, y); /*Read the projection, modelview and viewport matrices using the glGet functions.*/ glGetIntegerv( GL_VIEWPORT, viewport ); glGetDoublev( GL_MODELVIEW_MATRIX, modelview ); glGetDoublev( GL_PROJECTION_MATRIX, projection ); //Read the window z value from the z-buffer glReadBuffer(GL_FRONT); glReadPixels( x, viewport[ 3 ]-y, 1 , 1 , GL_DEPTH_COMPONENT, GL_FLOAT, &z ); //Use the gluUnProject to get the world co-ordinates of //the point the user clicked and save in objx, objy, objz. gluUnProject( x, viewport[ 3 ]-y, z, modelview, projection, viewport, &objx, &objy, &objz ); qDebug( "World coords at z=%.1f are (%.3f, %.3f, %.3f)\n" , z, objx, objy, objz); updateGL(); } void GLWidget::draw() { glPushMatrix(); glBegin(GL_QUAD_STRIP); glColor3f( 1 , 0 , 0 ); glVertex3f( 0 .0f, 0 .0f, 0 .0f); glColor3f( 1 , 1 , 0 ); glVertex3f( 0 .0f, 1 .0f, 0 .0f); glColor3f( 0 , 1 , 0 ); glVertex3f( 1 .0f, 0 .0f, 0 .0f); glColor3f( 0 , 1 , 1 ); glVertex3f( 1 .0f, 1 .0f, 0 .0f); glColor3f( 1 , 0 , 0 ); glVertex3f( 1 .0f, 0 .0f, - 1 .0f); glColor3f( 1 , 1 , 0 ); glVertex3f( 1 .0f, 1 .0f, - 1 .0f); glColor3f( 0 , 1 , 0 ); glVertex3f( 0 .0f, 0 .0f, - 1 .0f); glColor3f( 0 , 1 , 1 ); glVertex3f( 0 .0f, 1 .0f, - 1 .0f); glColor3f( 1 , 0 , 0 ); glVertex3f( 0 .0f, 0 .0f, 0 .0f); glColor3f( 1 , 1 , 0 ); glVertex3f( 0 .0f, 1 .0f, 0 .0f); glEnd(); glBegin(GL_QUAD_STRIP); glColor3f( 0 , 0 , 1 ); glVertex3f( 0 .0f, 0 .0f, 0 .0f); glColor3f( 1 , 0 , 1 ); glVertex3f( 1 .0f, 0 .0f, 0 .0f); glColor3f( 0 , 1 , 0 ); glVertex3f( 0 .0f, 0 .0f, - 1 .0f); glColor3f( 1 , 0 , 0 ); glVertex3f( 1 .0f, 0 .0f, - 1 .0f); glColor3f( 1 , 1 , 0 ); glVertex3f( 0 .0f, 1 .0f, 0 .0f); glColor3f( 1 , 0 , 1 ); glVertex3f( 1 .0f, 1 .0f, 0 .0f); glColor3f( 0 , 0 , 1 ); glVertex3f( 0 .0f, 1 .0f, - 1 .0f); glColor3f( 1 , 0 , 0 ); glVertex3f( 1 .0f, 1 .0f, - 1 .0f); glEnd(); glPopMatrix(); } /*---------------------------------------------------------------------------*/ void GLWidget::DrawFloor() { glDepthMask(GL_FALSE); glColor4ub( 175 , 175 , 175 , 255 ); glBegin(GL_LINES); glNormal3d( 0 . 0 , 1 . 0 , 0 . 0 ); for (qint32 i = -s_Scale; i <= s_Scale; i += s_Scale >> 3 ) { glVertex3i(i, 0 , -s_Scale); glVertex3i(i, 0 , s_Scale); glVertex3i(-s_Scale, 0 , i); glVertex3i(s_Scale, 0 , i); } glEnd(); glDepthMask(GL_TRUE); } /*---------------------------------------------------------------------------*/ void GLWidget::DrawAxis( void ) { // Local Space static const qint32 s_Scale = 64 ; glPushAttrib( GL_LINE_BIT ); glLineWidth( 1 .0f ); glBegin( GL_LINES ); // X軸 glColor3ub( 255 , 0 , 0 ); glVertex3i( 0 , 0 , 0 ); glVertex3i( s_Scale, 0 , 0 ); // Y軸 glColor3ub( 0 , 255 , 0 ); glVertex3i( 0 , 0 , 0 ); glVertex3i( 0 , s_Scale, 0 ); // Z軸 glColor3ub( 0 , 0 , 255 ); glVertex3i( 0 , 0 , 0 ); glVertex3i( 0 , 0 , s_Scale ); glEnd( ); glPopAttrib( ); } |
代碼僅供參考，最近一直在研究這個，用於實現場景中單個對象的拖拽，效果還欠佳，歡迎交流討論。