NeHe 系列教程之十：在3D空间中漫游

英文教程地址：lesson10

本课演示了从外部文件中加载数据构建3D模型的实例，代码基于第一课。

首先是3D模型的数据结构定义：

namespace {bool fp;         // F pressed?const float piover180 = 0.0174532925f;float heading;float xpos;float zpos;GLfloat yrot;                   // Y RotationGLfloat walkbias = 0;GLfloat walkbiasangle = 0;GLfloat lookupdown = 0.0f;GLuint filter;         // Which filter to useGLuint texture[3];        // Storage for 3 texturestypedef struct tagVERTEX{float x, y, z;float u, v;} VERTEX;typedef struct tagTRIANGLE{VERTEX vertex[3];} TRIANGLE;typedef struct tagSECTOR{int numtriangles;TRIANGLE* triangle;} SECTOR;SECTOR sector1;         // Our model goes here:

接着是读取外部数据文件，构建3D模型：

const char* readstr(QFile &f){QByteArray line = f.readLine();while (line.at(0) == '/' || line.at(0) == '\n') {line = f.readLine();}return line.constData();}void SetupWorld(){float x, y, z, u, v;int numtriangles;const char *oneline;QFile filein(":/World.txt");if (!filein.open(QIODevice::ReadOnly | QIODevice::Text)) {qDebug("failed to open file");} else {qDebug("open file successfully");}oneline = readstr(filein);sscanf(oneline, "NUMPOLLIES %d\n", &numtriangles);sector1.triangle = new TRIANGLE[numtriangles];sector1.numtriangles = numtriangles;for (int loop = 0; loop < numtriangles; loop++){for (int vert = 0; vert < 3; vert++){oneline = readstr(filein);sscanf(oneline, "%f %f %f %f %f", &x, &y, &z, &u, &v);sector1.triangle[loop].vertex[vert].x = x;sector1.triangle[loop].vertex[vert].y = y;sector1.triangle[loop].vertex[vert].z = z;sector1.triangle[loop].vertex[vert].u = u;sector1.triangle[loop].vertex[vert].v = v;}}filein.close();return;}
}

采用了三种不同的纹理过滤方式， 加载纹理代码如下：

void MyGLWidget::loadTextures()
{QImage image;if (image.load(":/Mud.bmp")) {image =  convertToGLFormat(image);glGenTextures(3, texture);// Create Nearest Filtered TextureglBindTexture(GL_TEXTURE_2D, texture[0]);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width(), image.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, image.bits());// Create Linear Filtered TextureglBindTexture(GL_TEXTURE_2D, texture[1]);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width(), image.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, image.bits());// Create MipMapped TextureglBindTexture(GL_TEXTURE_2D, texture[2]);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST);gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, image.width(), image.height(), GL_RGBA, GL_UNSIGNED_BYTE, image.bits());}
}

在初始化代码中，调用构建3D模型函数，即：

void MyGLWidget::initializeGL()
{...SetupWorld();}

然后是绘制代码，将3D场景显示出来：

void MyGLWidget::paintGL()
{glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);     // Clear the screen and the depth bufferglLoadIdentity();                  // Reset the viewGLfloat x_m, y_m, z_m, u_m, v_m;GLfloat xtrans = -xpos;GLfloat ztrans = -zpos;GLfloat ytrans = -walkbias-0.25f;GLfloat sceneroty = 360.0f - yrot;int numtriangles;glRotatef(lookupdown,1.0f,0,0);glRotatef(sceneroty,0,1.0f,0);glTranslatef(xtrans, ytrans, ztrans);glBindTexture(GL_TEXTURE_2D, texture[filter]);numtriangles = sector1.numtriangles;// Process each trianglefor (int loop_m = 0; loop_m < numtriangles; loop_m++){glBegin(GL_TRIANGLES);glNormal3f( 0.0f, 0.0f, 1.0f);x_m = sector1.triangle[loop_m].vertex[0].x;y_m = sector1.triangle[loop_m].vertex[0].y;z_m = sector1.triangle[loop_m].vertex[0].z;u_m = sector1.triangle[loop_m].vertex[0].u;v_m = sector1.triangle[loop_m].vertex[0].v;glTexCoord2f(u_m,v_m); glVertex3f(x_m,y_m,z_m);x_m = sector1.triangle[loop_m].vertex[1].x;y_m = sector1.triangle[loop_m].vertex[1].y;z_m = sector1.triangle[loop_m].vertex[1].z;u_m = sector1.triangle[loop_m].vertex[1].u;v_m = sector1.triangle[loop_m].vertex[1].v;glTexCoord2f(u_m,v_m); glVertex3f(x_m,y_m,z_m);x_m = sector1.triangle[loop_m].vertex[2].x;y_m = sector1.triangle[loop_m].vertex[2].y;z_m = sector1.triangle[loop_m].vertex[2].z;u_m = sector1.triangle[loop_m].vertex[2].u;v_m = sector1.triangle[loop_m].vertex[2].v;glTexCoord2f(u_m,v_m); glVertex3f(x_m,y_m,z_m);glEnd();}
}

最后是键盘控制处理：

void MyGLWidget::keyReleaseEvent(QKeyEvent *e)
{switch (e->key()) {case Qt::Key_I:fp = false;break;default:QGLWidget::keyReleaseEvent(e);}
}void MyGLWidget::keyPressEvent(QKeyEvent *e)
{switch (e->key()) {case Qt::Key_I:fp = true;filter += 1;if (filter > 2)filter = 0;break;case Qt::Key_F:fullscreen = !fullscreen;if (fullscreen) {showFullScreen();} else {resize(640, 480);showNormal();}break;case Qt::Key_Right:yrot -= 1.5f;break;case Qt::Key_Left:yrot += 1.5f;break;case Qt::Key_Up:xpos -= (float)sin(heading*piover180) * 0.05f;          // Move On The X-Plane Based On Player Directionzpos -= (float)cos(heading*piover180) * 0.05f;          // Move On The Z-Plane Based On Player Directionif (walkbiasangle >= 359.0f)                 // Is walkbiasangle>=359?{walkbiasangle = 0.0f;                   // Make walkbiasangle Equal 0}else                                // Otherwise{walkbiasangle+= 10;                    // If walkbiasangle < 359 Increase It By 10}walkbias = (float)sin(walkbiasangle * piover180)/20.0f;     // Causes The Player To Bouncebreak;case Qt::Key_Down:xpos += (float)sin(heading*piover180) * 0.05f;          // Move On The X-Plane Based On Player Directionzpos += (float)cos(heading*piover180) * 0.05f;          // Move On The Z-Plane Based On Player Directionif (walkbiasangle <= 1.0f)                   // Is walkbiasangle<=1?{walkbiasangle = 359.0f;                 // Make walkbiasangle Equal 359}else                                // Otherwise{walkbiasangle-= 10;                 // If walkbiasangle > 1 Decrease It By 10}walkbias = (float)sin(walkbiasangle * piover180)/20.0f;     // Causes The Player To Bouncebreak;case Qt::Key_Escape:QMessageBox::StandardButton reply;reply = QMessageBox::question(NULL, "NeHe","Do you want to exit?",QMessageBox::Yes | QMessageBox::No,QMessageBox::Yes);if (reply == QMessageBox::Yes) {qApp->quit();}break;default:QGLWidget::keyPressEvent(e);break;}
}

最后运行效果如下所示：