在OpenGL中设置相机和视锥体

Question

为什么四元组没有被渲染出来？我已经尝试使用glOrtho和glFrustrum，输出结果都是黑屏。从我的理解来看，这段代码设置相机位置为(0,0,-3)，并且观察原点。近面位于-2（离相机1米远）。我做错了什么？

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
//glOrtho (-5,5,-5,5,-5,5);
glFrustum(-5,5,-5,5,1,1000);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0,0,-3,0,0,0,0,1,0);

glColor3f(1.0,1.0,1.0);
glBegin(GL_QUADS);                                  
glVertex3f(-0.5,-0.5,-0.5);
glVertex3f(0.5,-0.5,-0.5);
glVertex3f(0.5,0.5,-0.5);
glVertex3f(-0.5,0.5,-0.5);
glEnd();
// Don't wait start processing buffered OpenGL routines
glFlush();
glutSwapBuffers();

- Sara

Answer 1

对我来说它正常工作，你的代码其他部分可能有问题。

这是我使用的完整代码：

#include <GL/glut.h>

void display(void) {

  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glMatrixMode (GL_PROJECTION);
  glLoadIdentity ();
  //glOrtho (-5,5,-5,5,-5,5);
  glFrustum(-5,5,-5,5,1,1000);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt(0,0,-3,0,0,0,0,1,0);

  glColor3f(1.0,1.0,1.0);
  glBegin(GL_QUADS);                                  
  glVertex3f(-0.5,-0.5,-0.5);
  glVertex3f(0.5,-0.5,-0.5);
  glVertex3f(0.5,0.5,-0.5);
  glVertex3f(-0.5,0.5,-0.5);
  glEnd();
  // Don't wait start processing buffered OpenGL routines
  glFlush();
  glutSwapBuffers();

}

int main(int argc, char **argv) {
  glutInit(&argc, argv);

  glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);  
  glutInitWindowPosition(200,200);
  glutInitWindowSize(512,512);
  glutCreateWindow("Test");
  glutDisplayFunc(display);

  glutMainLoop();

  return 0;
}

我这样编译它：

我这样编译它：

gcc test.cpp -lGL -lglut -lGLU -o test

这是一张截图：

- Dagg Nabbit