C++-创建几何图形

我在大学被指派编译给我们的代码并识别：

• 已使用的OpenGL基元的类型
• 已经创建了多少个基元
• 已经创建了多少个顶点
• 网格的属性

给我们的代码应该创建一个多维数据集，但它没有。我已经看了好几个小时了，不知道为什么。

我想这可能是因为">createCube()"在主体中根本没有提到，所以我添加了">场景=createCube然而，一开始这给了我一个错误，createCube()尚未定义。经过几个小时的摆弄，我不再得到这个错误，尽管仍然没有立方体。我只看到一扇空窗户。

它不起作用也没关系，因为我可以在没有看到立方体的情况下回答问题，但是任务的下一部分是创建一个四面体而不是立方体，为此我需要代码来工作。

如果有人能看到我缺少的东西，我们将不胜感激。

// Geometry
//
// This tutorial supports learning
// about assembling a scene in a scene graph
// using transformation cores
// headers for OpenSG configuration and GLUT
#include <OpenSG/OSGGLUT.h>
#include <OpenSG/OSGConfig.h>
#include <OpenSG/OSGSimpleGeometry.h>
#include <OpenSG/OSGGLUTWindow.h>
#include <OpenSG/OSGSimpleSceneManager.h>
#include <OpenSG/OSGSceneFileHandler.h>
#include <OpenSG/OSGGeoProperties.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/gl.h>
// Simple Scene manager for accesing cameras and geometry
OSG::SimpleSceneManagerRefPtr mgr;
int setupGLUT(int *argc, char *argv[]);
int main(int argc, char **argv)
{
// initialise OpenSG
OSG::osgInit(argc, argv);
// initialise GLUT
int winid = setupGLUT(&argc, argv);
{
// create a OSGGLUT window
OSG::GLUTWindowRefPtr gwin = OSG::GLUTWindow::create();
gwin->setGlutId(winid);
gwin->init();

//read the file which will be passed as an argument
OSG::NodeRefPtr scene = OSG::Node::create();
OSG::NodeRefPtr createCube = OSG::Node::create();
scene = createCube;
//commit all changes to OpenSG 
OSG::commitChanges();
// create the SimpleSceneManager helper
mgr = OSG::SimpleSceneManager::create();
// tell the manager what to manage
mgr->setWindow(gwin);
mgr->setRoot(scene);
// show the whole scene
mgr->showAll();
}
// GLUT main loop
glutMainLoop();
return 0;
}
//
// GLUT callback functions
//
// redraw the window
void display(void)
{
mgr->redraw();
}
// react to size changes
void reshape(int w, int h)
{
mgr->resize(w, h);
glutPostRedisplay();
}
// react to mouse button presses
void mouse(int button, int state, int x, int y)
{
if (!state)
mgr->mouseButtonPress(button, x, y);
glutPostRedisplay();
}
// react to mouse motions with pressed buttons
void motion(int x, int y)
{
mgr->mouseMove(x, y);
glutPostRedisplay();
}
// react to keys
void keyboard(unsigned char k, int x, int y)
{
switch (k)
{
case 'e':
{
// clean up global variables
mgr = NULL;
OSG::osgExit();
exit(0);
}
break;
case 's':
{
mgr->setStatistics(!mgr->getStatistics());
}
break;
}
}
// setup the GLUT library which handles the windows for us
int setupGLUT(int *argc, char *argv[])
{
glutInit(argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
int winid = glutCreateWindow("05 Transformations Tutorial");
glutReshapeFunc(reshape);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutMotionFunc(motion);
glutKeyboardFunc(keyboard);
return winid;
}
OSG::NodeRefPtr createCube()
{
//create a node to hold the geometry
OSG::NodeRefPtr geonode = OSG::Node::create();
//create a geometry
OSG::GeometryRefPtr geo = OSG::Geometry::create();
//The primitive types.
//OpenGL provides us with several different types of shapes that we can     draw 
//(e.g. GL_LINES, GL_POLYGON, GL_QUADS, GL_TRIANGLES)
//we need to specify the type of geometry we want to use
//lets start by using only triangles (although different types can be     freely mixed)
OSG::GeoUInt8PropertyRefPtr type = OSG::GeoUInt8Property::create();
//MODIFY HERE 
type->addValue(GL_TRIANGLES);
//The primitive lengths.
//These define the number of vertices to be passed to OpenGL for     each primitive. 
//Thus there have to be at least as many entries as in the types     property.
//in the case of the cube we are using 12 triangles which each have 3     vertices (12 X 3 = 36) 
OSG::GeoUInt32PropertyRefPtr lens = OSG::GeoUInt32Property::create();
//MODIFY HERE 
lens->addValue(36);

// The vertices.
OSG::GeoPnt3fPropertyRefPtr  pnts = OSG::GeoPnt3fProperty::create();
//MODIFY HERE with positions of your geometry
pnts->addValue(OSG::Pnt3f(-0.5, 0.5, 0.5));
pnts->addValue(OSG::Pnt3f(0.5, 0.5, 0.5));
pnts->addValue(OSG::Pnt3f(0.5, -0.5, 0.5));
pnts->addValue(OSG::Pnt3f(-0.5, -0.5, 0.5));
pnts->addValue(OSG::Pnt3f(-0.5, 0.5, -0.5));
pnts->addValue(OSG::Pnt3f(0.5, 0.5, -0.5));
pnts->addValue(OSG::Pnt3f(0.5, -0.5, -0.5));
pnts->addValue(OSG::Pnt3f(-0.5, -0.5, -0.5));
// The normals.
//These are used for lighting calculations and have to point away from     the
//surface. Normals are standard vectors. 
OSG::GeoVec3fPropertyRefPtr  norms = OSG::GeoVec3fProperty::create();
norms->push_back(OSG::Vec3f(0, 0, 1));
norms->push_back(OSG::Vec3f(1, 0, 0));
norms->push_back(OSG::Vec3f(0, 0, -1));
norms->push_back(OSG::Vec3f(-1, 0, 0));
norms->push_back(OSG::Vec3f(0, 1, 0));
norms->push_back(OSG::Vec3f(0, -1, 0));
// The colours.   
// GeoColor3fProperty stores all color values that will be used
OSG::GeoColor3fPropertyRecPtr colors =     OSG::GeoColor3fProperty::create();
colors->addValue(OSG::Color3f(0, 0, 1));
colors->addValue(OSG::Color3f(0, 0, 1));
colors->addValue(OSG::Color3f(0, 0, 1));
colors->addValue(OSG::Color3f(0, 0, 1));
colors->addValue(OSG::Color3f(0, 0, 1));
colors->addValue(OSG::Color3f(0, 0, 1));
// The indices.
// in order not to replicate the same positions all the time, 
// use index number of the position 
OSG::GeoUInt32PropertyRefPtr indices = OSG::GeoUInt32Property::create();
//face 1: front 
//face 1 - triangle 1
indices->addValue(0);
indices->addValue(2);
indices->addValue(1);
//face 1 - triangle 2
indices->addValue(0);
indices->addValue(3);
indices->addValue(2);

//face 2: right 
//face 2 - triangle 1
indices->addValue(1);
indices->addValue(2);
indices->addValue(6);
//face 3 - triangle 2
indices->addValue(1);
indices->addValue(6);
indices->addValue(5);

//face 3: back
//face 3 - triangle 1
indices->addValue(5);
indices->addValue(6);
indices->addValue(7);
//face 3 - triangle 2
indices->addValue(5);
indices->addValue(7);
indices->addValue(4);

//face 4: left
//face 4 - triangle 1
indices->addValue(4);
indices->addValue(7);
indices->addValue(3);
//face 4 - triangle 2
indices->addValue(4);
indices->addValue(3);
indices->addValue(0);
//face 5: top
//face 5 - triangle 1
indices->addValue(4);
indices->addValue(1);
indices->addValue(5);
//face 5 - triangle 2
indices->addValue(4);
indices->addValue(0);
indices->addValue(1);
//face 6: bottom
//face 6 - triangle 1
indices->addValue(2);
indices->addValue(3);
indices->addValue(7);
//face 6 - triangle 2
indices->addValue(2);
indices->addValue(7);
indices->addValue(6);

// The indices for colours and normals
// as normals are different for each side of the cube, we use a special         index for this property
OSG::GeoUInt32PropertyRefPtr indicesnormpos =     OSG::GeoUInt32Property::create();
//face 1: front 
//face 1 - triangle 1
indicesnormpos->addValue(0);
indicesnormpos->addValue(0);
indicesnormpos->addValue(0);
//face 1 - triangle 2
indicesnormpos->addValue(0);
indicesnormpos->addValue(0);
indicesnormpos->addValue(0);

//face 2: right 
//face 2 - triangle 1
indicesnormpos->addValue(1);
indicesnormpos->addValue(1);
indicesnormpos->addValue(1);
//face 3 - triangle 2
indicesnormpos->addValue(1);
indicesnormpos->addValue(1);
indicesnormpos->addValue(1);

//face 3: back
//face 3 - triangle 1
indicesnormpos->addValue(2);
indicesnormpos->addValue(2);
indicesnormpos->addValue(2);
//face 3 - triangle 2
indicesnormpos->addValue(2);
indicesnormpos->addValue(2);
indicesnormpos->addValue(2);

//face 4: left
//face 4 - triangle 1
indicesnormpos->addValue(3);
indicesnormpos->addValue(3);
indicesnormpos->addValue(3);
//face 4 - triangle 2
indicesnormpos->addValue(3);
indicesnormpos->addValue(3);
indicesnormpos->addValue(3);
//face 5: top
//face 5 - triangle 1
indicesnormpos->addValue(4);
indicesnormpos->addValue(4);
indicesnormpos->addValue(4);
//face 5 - triangle 2
indicesnormpos->addValue(4);
indicesnormpos->addValue(4);
indicesnormpos->addValue(4);
//face 6: bottom
//face 6 - triangle 1
indicesnormpos->addValue(5);
indicesnormpos->addValue(5);
indicesnormpos->addValue(5);
//face 6 - triangle 2
indicesnormpos->addValue(5);
indicesnormpos->addValue(5);
indicesnormpos->addValue(5);
// Put it all together into a Geometry NodeCore.
geo->setTypes(type);
geo->setLengths(lens);
geo->setProperty(pnts, OSG::Geometry::PositionsIndex);
geo->setIndex(indices, OSG::Geometry::PositionsIndex);
geo->setProperty(norms, OSG::Geometry::NormalsIndex);
geo->setIndex(indicesnormpos, OSG::Geometry::NormalsIndex);
geo->setProperty(colors, OSG::Geometry::ColorsIndex);
geo->setIndex(indicesnormpos, OSG::Geometry::ColorsIndex);
// if you were not using any indexing you will simply use:
//geo->setTypes    (type);
//geo->setLengths  (lens);
//geo->setPositions (pnts);
//geo->setNormals   (norms);
//geo->setColors    (colors);        
geonode->setCore(geo);
return geonode;
}