Want to draw a rectangle, with OpenGL program code is as follows:

 # include & lt; GL/glut. H> 
Void the display ()//defines to draw graphics entities 
{
GlClear (GL_COLOR_BUFFER_BIT); 
GlBegin (GL_POLYGON); 
GlVertex2f (0.5, 0.5); 
GlVertex2f (0.5, 0.5); 
GlVertex2f (0.5, 0.5); 
GlVertex2f (0.5, 0.5); 
GlEnd (); 
GlFlush (); 
} 

Int main (int arg c, char * * argv)//OpenGL initialization 
{
GlutInit (& amp; Arg c, argv); 
GlutCreateWindow (" simple "); 
GlutDisplayFunc (display); 
GlutMainLoop (); 
} 

But shows results for:


Tell please, thanks! ^_^

CodePudding user response:

Is the cause of the rendering, GL_POLYGON way of drawing as follows: if there is V1, V2, V3 and V4. So will the V1, V2, V3 draw a triangle, V1 and V3, V4 draw a triangle,