如何在一些世界坐标绘制立方体，OpenGL

Question

我有这样做的代码，但它根本不起作用！

GLdouble *posv = Utils::worldToScreen(px, py, pz); 
GLdouble x = posv[0]; 
GLdouble y = posv[1]; 
GLdouble z = posv[2]; 
GLdouble *sizev = Utils::worldToScreen(1.0f, 1.0f, 1.0f); 
GLdouble sizex = sizev[0]; 
GLdouble sizey = sizev[1]; 
GLdouble sizez = sizev[2]; 

glBegin(GL_QUADS); 
glColor3f(1.0, 1.0, 0.0); 
// FRONT 
glVertex3f(x-sizex, y-sizey, z+sizez); 
glVertex3f(x+sizex, y-sizey, z+sizez); 
glVertex3f(x+sizex, y+sizey, z+sizez); 
glVertex3f(x-sizex, y+sizey, z+sizez); 
// BACK 
glVertex3f(x-sizex, y-sizey, z-sizez); 
glVertex3f(x-sizex, y+sizey, z-sizez); 
glVertex3f(x+sizex, y+sizey, z-sizez); 
glVertex3f(x+sizex, y-sizey, z-sizez); 

glColor3f(0.0, 1.0, 0.0); 
// LEFT 
glVertex3f(x-sizex, y-sizey, z+sizez); 
glVertex3f(x-sizex, y+sizey, z+sizez); 
glVertex3f(x-sizex, y+sizey, z-sizez); 
glVertex3f(x-sizex, y-sizey, z-sizez); 
// RIGHT 
glVertex3f(x+sizex, y-sizey, z-sizez); 
glVertex3f(x+sizex, y+sizey, z-sizez); 
glVertex3f(x+sizex, y+sizey, z+sizez); 
glVertex3f(x+sizex, y-sizey, z+sizez); 

glColor3f(0.0, 0.0, 1.0); 
// TOP 
glVertex3f(x-sizex, y+sizey, z+sizez); 
glVertex3f(x+sizex, y+sizey, z+sizez); 
glVertex3f(x+sizex, y+sizey, z-sizez); 
glVertex3f(x-sizex, y+sizey, z-sizez); 
// BOTTOM 
glVertex3f(x-sizex, y-sizey, z+sizez); 
glVertex3f(x-sizex, y-sizey, z-sizez); 
glVertex3f(x+sizex, y-sizey, z-sizez); 
glVertex3f(x+sizex, y-sizey, z+sizez); 


GLdouble* Utils::worldToScreen(float objX, float objY, float objZ) { 

GLint realy; 
GLdouble win_x, win_y, win_z; 
int viewport[4]; 
double mvmatrix[16], projmatrix[16]; 

glGetIntegerv(GL_VIEWPORT, viewport); 
glGetDoublev(GL_MODELVIEW_MATRIX, mvmatrix); 
glGetDoublev(GL_PROJECTION_MATRIX, projmatrix); 


gluProject(static_cast<GLdouble>(objX), static_cast<GLdouble>(objY), static_cast<GLdouble>(objZ), mvmatrix, projmatrix, viewport, &win_x, &win_y, &win_z); 

realy = viewport[3]-(GLint)win_y -1; 

GLdouble *temp = new GLdouble[3]; 
temp[0] = win_x; 
temp[1] = realy; 
temp[2] = win_z; 

cout << "objX:" << objX << endl; 
cout << "objY:" << objY << endl; 
cout << "objZ:" << objZ << endl; 
cout << "temp[0]:" << temp[0] << endl; 
cout << "temp[1]:" << temp[1] << endl; 
cout << "temp[2]:" << temp[2] << endl; 

return temp; } 

输出很奇怪！

objX:100 
objY:100 
objZ:0 
temp[0]:6.95322e-310 
temp[1]:-1 
temp[2]:6.95322e-310 

怎么了？对不起，我的愚蠢！

Answer 1

而不是在x +/-大小，y +/-大小，z +/-大小绘制顶点，为什么不用glTranslatef（）将其转换为x，y，z然后进行绘制？

试试这个作为你绘制函数：

void drawCube(float x, float y, float z) 
{ 
    const float sizex = 0.5f; 
    const float sizey = 0.5f; 
    const float sizez = 0.5f 

    glTranslatef(-x, -y, -z); 

    glBegin(GL_QUADS); 

    glColor3f(1.0, 1.0, 0.0); 

    // FRONT 
    glVertex3f(-sizex, -sizey, sizez); 
    glVertex3f(sizex, -sizey, sizez); 
    glVertex3f(sizex, sizey, sizez); 
    glVertex3f(-sizex, sizey, sizez); 

    // BACK 
    glVertex3f(-sizex, -sizey, -sizez); 
    glVertex3f(-sizex, sizey, -sizez); 
    glVertex3f(sizex, sizey, -sizez); 
    glVertex3f(sizex, -sizey, -sizez); 

    glColor3f(0.0, 1.0, 0.0); 

    // LEFT 
    glVertex3f(-sizex, -sizey, sizez); 
    glVertex3f(-sizex, sizey, sizez); 
    glVertex3f(-sizex, sizey, -sizez); 
    glVertex3f(-sizex, -sizey, -sizez); 

    // RIGHT 
    glVertex3f(sizex, -sizey, -sizez); 
    glVertex3f(sizex, sizey, -sizez); 
    glVertex3f(sizex, sizey, sizez); 
    glVertex3f(sizex, -sizey, sizez); 

    glColor3f(0.0, 0.0, 1.0); 

    // TOP 
    glVertex3f(-sizex, sizey, sizez); 
    glVertex3f(sizex, sizey, sizez); 
    glVertex3f(sizex, sizey, -sizez); 
    glVertex3f(-sizex, sizey, -sizez); 

    // BOTTOM 
    glVertex3f(-sizex, -sizey, sizez); 
    glVertex3f(-sizex, -sizey, -sizez); 
    glVertex3f(sizex, -sizey, -sizez); 
    glVertex3f(sizex, -sizey, sizez); 

    glEnd(); 

    glTranslatef(x, y, z); 
}