perl-opengl-直线绘制

asfsd

#!/usr/bin/perl -w
use strict;
use warnings;
use OpenGL qw/ :all /;
use OpenGL::Config;   
glutInit();
glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
glutInitWindowPosition(100,100);
glutInitWindowSize(400,400);
glutCreateWindow("my  OpenGL program");
glClearColor(0,0,0,255);
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
gluOrtho2D(-100,100,-100,100);
glutDisplayFunc(\&mydis);
glutMainLoop();
return 0;
sub mydis()
{
my $x0=-100;
my $y0=-85;  
my $xend=93;
my $yend=26;
my $dx=abs($xend-$x0);
my $dy=abs($yend-$y0);
my $p=2*$dy-$dx;
my $twoDy=2*$dy;
my $twoDyMinusDx=2*($dy-$dx);
my $x;
my $y;
glPointSize(1);
glColor3f(255,0,255);  
if ($x0>$xend)
{
$x=$xend;
$y=$yend;
$xend=$x0;
}
else
{
$x=$x0;
$y=$y0;
}
glBegin(GL_POINTS);
glVertex2f($x,$y);
glEnd();  
glFlush();
for (;$x<$xend;$x++)
{
if ($p<0)
{
$p+=$twoDy;
}
else
{
$y++;
$p+=$twoDyMinusDx;
}
glBegin(GL_POINTS);
glVertex2f($x,$y);
glEnd();  
}
glFlush();
glColor3f(0,255,0);
glBegin(GL_LINES);
glVertex2f(-100,0);
glVertex2f(100,0);
glEnd();
glBegin(GL_LINES);
glVertex2f(0,-100);
glVertex2f(0,100);
glEnd();  
glFlush();
}