3D物体

本文基于“第一个OpenGL程序”，将绘制一个绕Y族旋转的金字塔，一个绕XYZ族旋转的立方体。绘制多边形时，都按照逆时针进行绘制，今后的课程将进行解释。

wglwidget.h

#ifndef WGLWIDGET_H#define WGLWIDGET_H#include <QtGui/QWidget>#include <QtOpenGL/QtOpenGL>#include "ui_wglwidget.h"class WGLWidget : public QGLWidget , public Ui::WGLWidgetClass{Q_OBJECTpublic:WGLWidget(QWidget *parent = 0, const QGLWidget* shareEidget = 0,Qt::WFlags flags = 0);~WGLWidget();protected:virtual void initializeGL();virtual void resizeGL(int w, int h);virtual void paintGL();virtual void mouseDoubleClickEvent(QMouseEvent *event);virtual void closeEvent(QCloseEvent *event);virtual void timerEvent(QTimerEvent *event);private:floatm_fTri;///< 金字塔旋转角度floatm_fCube;///< 立方体旋转角度};#endif // WGLWIDGET_H

 

wglwidget.cpp

#include "wglwidget.h"#include <math.h>const GLfloat PI = 3.1415926536f;WGLWidget::WGLWidget(QWidget *parent /* = 0 */, const QGLWidget* shareEidget /* = 0 */,Qt::WFlags flags /* = 0 */): QGLWidget(parent, shareEidget, flags), m_fTri(0.0), m_fCube(0.0){setupUi(this);setMinimumSize(320,240);resize(640,480);setWindowTitle(tr("3D空间"));// 启用定时器startTimer(10);}WGLWidget::~WGLWidget(){}void WGLWidget::initializeGL(){glShadeModel(GL_SMOOTH);glClearColor(0.0,0.0,0.0,0.0);glClearDepth(1.0);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL);glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);}void WGLWidget::resizeGL(int w, int h){// 视口glViewport(0,0,(GLint)width(),(GLint)height());// 投影变换glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(45.0,(GLfloat)width() / (GLfloat)height(),0.1,100.0);// 视图模型变换glMatrixMode(GL_MODELVIEW);glLoadIdentity();}void WGLWidget::paintGL(){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glPushMatrix();glTranslatef(0.0,0.0,-6.0);// 所有面都按照逆时针方向绘制// 绘制圆锥glPushMatrix();// 左移个单位glTranslatef(-1.5,0.0,0.0);// 饶Y族旋转glRotatef(m_fTri,0.0,1.0,0.0);// 开始绘制glBegin(GL_TRIANGLES);// 前面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);// 右侧面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);// 左侧面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);// 底面glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);glEnd();glPopMatrix();// 绘制立方体glPushMatrix();// 右移.5个单位glTranslatef(1.5,0.0,0.0);// 饶XYZ族旋转立方体glRotatef(m_fCube,1.0,1.0,1.0);// 开始绘制glBegin(GL_QUADS);//顶面glColor3f(0.0,1.0,0.0);// 颜色改为蓝色glVertex3f(-1.0,1.0,-1.0);glVertex3f(-1.0,1.0,1.0);glVertex3f(1.0,1.0,1.0);glVertex3f(1.0,1.0,-1.0);// 底面glColor3f(1.0f,0.5f,0.0f);// 颜色改成橙色glVertex3f(-1.0,-1.0,-1.0);glVertex3f(-1.0,-1.0,1.0);glVertex3f(1.0,-1.0,1.0);glVertex3f(1.0,-1.0,-1.0);// 左面glColor3f(1.0f,0.0f,0.0f);// 颜色改成红色glVertex3f(-1.0,1.0,-1.0);glVertex3f(-1.0,1.0,1.0);glVertex3f(-1.0,-1.0,1.0);glVertex3f(-1.0,-1.0,-1.0);// 前面glColor3f(1.0f,1.0f,0.0f);// 颜色改成黄色glVertex3f(-1.0,1.0,1.0);glVertex3f(-1.0,-1.0,1.0);glVertex3f(1.0,-1.0,1.0);glVertex3f(1.0,1.0,1.0);// 右面glColor3f(0.0f,0.0f,1.0f);// 颜色改成蓝色glVertex3f(1.0,1.0,-1.0);glVertex3f(1.0,1.0,1.0);glVertex3f(1.0,-1.0,1.0);glVertex3f(1.0,-1.0,-1.0);// 里面glColor3f(1.0f,0.0f,1.0f);// 颜色改成紫罗兰色glVertex3f(-1.0,1.0,-1.0);glVertex3f(-1.0,-1.0,-1.0);glVertex3f(1.0,-1.0,-1.0);glVertex3f(1.0,1.0,-1.0);glEnd();glPopMatrix();glPopMatrix();}void WGLWidget::mouseDoubleClickEvent(QMouseEvent *event){if(windowState() & Qt::WindowFullScreen)showNormal();elseshowFullScreen();}void WGLWidget::timerEvent(QTimerEvent *event){m_fTri += 1.0;m_fCube -= 0.5;update();}void WGLWidget::closeEvent(QCloseEvent *event){QMessageBox box;box.setWindowTitle(tr("退出"));box.setIcon(QMessageBox::Warning);box.setText(tr("确定要关闭OpenGL窗口吗？"));box.setStandardButtons(QMessageBox::Yes | QMessageBox::No);if(QMessageBox::No == box.exec()){event->ignore();return;}QWidget::closeEvent(event);}

 

从绘制立方体的代码可以看出，有许多顶点是重复的；调用的函数也相同。OpenGL提供了顶点数组。利用顶点数组可以减少函数的使用数量和数据传输数量。程序做如下修改：

void WGLWidget::initializeGL(){glShadeModel(GL_SMOOTH);glClearColor(0.0,0.0,0.0,0.0);glClearDepth(1.0);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL);glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);// 立方体顶点坐标static GLfloat vertexPoint[][3] = {-1.0,1.0,1.0,-1.0,-1.0,1.0,1.0,-1.0,1.0,1.0,1.0,1.0,-1.0,1.0,-1.0,-1.0,-1.0,-1.0,1.0,-1.0,-1.0,1.0,1.0,-1.0};// 启用顶点数组glEnableClientState(GL_VERTEX_ARRAY);// 指定顶点数组数据glVertexPointer(3,GL_FLOAT,0,vertexPoint);}void WGLWidget::paintGL(){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glPushMatrix();glTranslatef(0.0,0.0,-6.0);// 所有面都按照逆时针方向绘制// 绘制圆锥glPushMatrix();// 左移个单位glTranslatef(-1.5,0.0,0.0);// 饶Y族旋转glRotatef(m_fTri,0.0,1.0,0.0);// 开始绘制glBegin(GL_TRIANGLES);// 前面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);// 右侧面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);// 左侧面glColor3f(1.0,0.0,0.0);// 上顶点，红色glVertex3f(0.0,1.0,0.0);glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);// 底面glColor3f(0.0,0.0,1.0);// 里顶点，蓝色glVertex3f(0.0,-1.0,-1.0);glColor3f(0.0,1.0,0.0);// 左顶点，绿色glVertex3f(-1.0,-1.0,1.0);glColor3f(0.0,0.0,1.0);// 右顶点，蓝色glVertex3f(1.0,-1.0,1.0);glEnd();glPopMatrix();// 绘制立方体glPushMatrix();// 右移.5个单位glTranslatef(1.5,0.0,0.0);// 饶XYZ族旋转立方体glRotatef(m_fCube,1.0,1.0,1.0);// 开始绘制static GLubyte frontIndices[] = {0,1,2,3};static GLubyte rightIndices[] = {3,2,6,7};static GLubyte backIndices[] = {7,6,5,4};static GLubyte leftIndices[] = {4,5,1,0};static GLubyte topIndices[] = {4,0,3,7};static GLubyte botIndices[] = {5,6,2,1};glColor3f(1.0f,1.0f,0.0f);// 颜色改成黄色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,frontIndices);glColor3f(0.0,1.0,0.0);// 颜色改为蓝色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,rightIndices);glColor3f(1.0f,0.5f,0.0f);// 颜色改成橙色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,backIndices);glColor3f(1.0f,0.0f,0.0f);// 颜色改成红色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,leftIndices);glColor3f(0.0f,0.0f,1.0f);// 颜色改成蓝色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,topIndices);glColor3f(1.0f,0.0f,1.0f);// 颜色改成紫罗兰色glDrawElements(GL_QUADS,4,GL_UNSIGNED_BYTE,botIndices);glPopMatrix();glPopMatrix();}

程序运行效果如图：

 

图1.1 程序运行效果