C ++错误：对“”的未定义引用，并且ld返回了1个退出状态[重复]

Question

我创建了一个OpenGL项目来绘制形状。但是，当我尝试编译程序时，出现一些错误。这是Shapes.h的内容：

#ifndef SHAPES_INCLUDE
#define SHAPES_INCLUDE
void Triangle(int x1, int y1, int x2, int y2, int x3, int y3 , float r, float g, float b);

#endif

这里是“ Shapes.cpp”的内容：

#include "Shapes.h"
#include <GL/glx.h>    
#include <GL/gl.h>
#include <GL/glut.h>

void Triangle(int x1, int y1, int x2, int y2, int x3, int y3 , float r, float g, float b)
{
    glColor3f(r,g,b);
        glBegin(GL_TRIANGLES);
            glVertex2i(x1,y1);
            glVertex2i(x2,y2);
            glVertex2i(x3,y3);
    glEnd();
}

供参考，这是我的“ main.cpp”的内容：

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <GL/glx.h>    
#include <GL/gl.h>
#include <GL/glut.h>

// our libraries:

#include "libraries/Shapes.h"

void init()
{
    glClearColor(1.0,1.0,1.0,0.0);
    glMatrixMode(GL_PROJECTION);
    gluOrtho2D(0.0,200.0,0.0,150.0);
 }

 void lineSegment()
 {
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(0.0,0.0,1.0);
        glBegin(GL_TRIANGLES);
            glVertex2i(20,120);
            glVertex2i(40,20);
            glVertex2i(80,20);
        glEnd();
    glFlush();
 }

 void glLoop()
 {
     Triangle(20,120,40,20,80,20,0.0,0.0,1.0);
     glFlush();
 }

 int main(int argc, char**argv)
 {
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutInitWindowPosition(50,100);
    glutInitWindowSize(400,300);
    glutCreateWindow("OpenGL window");
    init();
    glutDisplayFunc(glLoop);
    glutMainLoop();
    return 0;
 }

并且当我用g++ main.cpp -lGL -lGLU -lglut编译时，出现此错误：

/tmp/ccSGyfe8.o: In function `glLoop()':
main.cpp:(.text+0xf3): undefined reference to `Triangle(int, int, int, int, int, int, float, float, float)'
collect2: error: ld returned 1 exit status

有人可以帮我修复它吗？