真正的等距投影与opengl

问题描述

我是使用C ++的OpenGL编程的新手，而不是很好的数学。有一个简单的方法来等距投影吗？

我的意思是

  glClearColor（0.0，0.0，0.0，1.0）; 
 glClear（GL_COLOR_BUFFER_BIT）; 
 
 glMatrixMode（GL_PROJECTION）; 
 glLoadIdentity（）; 
 
 / *使用这个长度，以便摄像机离原点1个单位* / 
 double dist = sqrt（1 / 3.0）; 
 
 gluLookAt（dist，dist，dist，/ * camera的相对位置* / 
 0.0，0.0，0.0，/ *相机指向* / 
 0.0，1.0， 0.0）; / *哪个方向向上* / 
 glMatrixMode（GL_MODELVIEW）; 
 
 glBegin（GL_LINES）; 
 
 glColor3d（1.0，0.0，0.0）; 
 glVertex3d（0.0，0.0，0.0）; 
 glVertex3d（1.0，0.0，0.0）; 
 
 glColor3d（0.0，1.0，0.0）; 
 glVertex3d（0.0，0.0，0.0）; 
 glVertex3d（0.0，1.0，0.0）; 
 
 glColor3d（0.0，0.0，1.0）; 
 glVertex3d（0.0，0.0，0.0）; 
 glVertex3d（0.0，0.0，1.0）; 
 
 glEnd（）; 
 
 glFlush（）; 
  

结果

我们可以绘制一个立方体来检查并行线确实是并行

  glPushMatrix 
 glTranslated（0.5，0.5，0.5）; 
 glColor3d（0.5，0.5，0.5）; 
 glutWireCube（1）; 
 glPopMatrix（）;    202.pngalt =alt text> 
 
I am a newbie in OpenGL programming with C++ and not very good at mathematics. Is there a simple way to have isometric projection?

I mean the true isometric projection, not the general orthogonal projection.

(Isometric projection happens only when projections of unit X, Y and Z vectors are equally long and angles between them are exactly 120 degrees.)

Code snippets are highly appreciated..
 解决方案 
Try using gluLookAt
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

/* use this length so that camera is 1 unit away from origin */
double dist = sqrt(1 / 3.0);

gluLookAt(dist, dist, dist,  /* position of camera */
          0.0,  0.0,  0.0,   /* where camera is pointing at */
          0.0,  1.0,  0.0);  /* which direction is up */
glMatrixMode(GL_MODELVIEW);

glBegin(GL_LINES);

glColor3d(1.0, 0.0, 0.0);
glVertex3d(0.0, 0.0, 0.0);
glVertex3d(1.0, 0.0, 0.0);

glColor3d(0.0, 1.0, 0.0);
glVertex3d(0.0, 0.0, 0.0);
glVertex3d(0.0, 1.0, 0.0);

glColor3d(0.0, 0.0, 1.0);
glVertex3d(0.0, 0.0, 0.0);
glVertex3d(0.0, 0.0, 1.0);

glEnd();

glFlush();
Results in
We can draw a cube to check that parallel lines are indeed parallel
glPushMatrix();
glTranslated(0.5, 0.5, 0.5);
glColor3d(0.5, 0.5, 0.5);
glutWireCube(1);
glPopMatrix();
                        
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