一段OpenGL的简单代码

这是基于OpenGL的代码，把它放进draw中即可。渲染出来的效果还不错

 #define  PI 3.14159
 #define  N  100
 void test::Draw()
 {
   glClearColor(0.0f, 0.0f, 0.0f, 1.0f);            // 设置刷新背景色
   glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);// 刷新背景
   glLoadIdentity();
   glEnable( GL_BLEND );
   glBlendFunc( GL_SRC_ALPHA, GL_ONE );
   glDisable( GL_DEPTH_TEST );
   glDisable( GL_TEXTURE_2D );

 #pragma region 圆圈轨迹
   glPushMatrix();
     glColor4f(1.0f,1.0f,1.0f,1.0f);
     float step,zstep;
     step=1.0*PI/N;
     zstep=1.0/N;
     glBegin(GL_LINES);
       float factor=2.0f;
       float length=3.0f;
       float HOT=2.0f;
       float COLD=0.0f;
       GLfloat z=0.0f;
       while (factor>)
       {
         setColor(length,HOT,COLD);
         for (int i=;i<(int)(*N);i++)
         {
           GLfloat x=factor*cos(step*i);
           GLfloat y=factor*sin(step*i);
           //GLfloat z=zstep*i;
           glVertex3f(x,y,z);
           glVertex3f(x,y,z+length);
         }
         factor=factor-0.05f;
         length=length-0.1f;
       }
     glEnd();
   glPopMatrix();
 #pragma endregion
 }

 void test::setColor(float t,float HOT,float COLD)
 {
   float r,g,b;
   r=(t-COLD)/(HOT-COLD);
   g=0.0;
   b=1.0-r;
   glColor3f(r,g,b);
 }