Membuat 4 garis dengan titik Basic4gl

Posting kali ini mengenai membuat 4 garis dengan pembangkitan titik titik menggunakan basic4gl. Dan source code nya seperti berikut :

const XSize = 640, YSize = 480
 glMatrixMode (GL_PROJECTION)
 glLoadIdentity ()
 glOrtho (0, XSize, YSize, 0, 0, 1)
 glDisable(GL_DEPTH_TEST)
 glMatrixMode (GL_MODELVIEW)
 glLoadIdentity()
 ' Displacement trick for exact pixelization
 glTranslatef(0.375, 0.375, 0)

 ' Variables
 dim angle#, x1, x2, x3, x4, y1, y2, y3, y4
 dim i
 dim switch

 ' Draw a scene
 glClearColor(.3, .3, .3, 0)

for i = 1 to 400
 x1 = i
 gosub piksel
 next
 
 for i = 1 to 100
 x2 = x2+4
 y2 = 15
 gosub piksel
 next 
  
 for i = 1 to 600
 switch=switch+1  

 if switch<=1 then
 x3 = x3+9
 y3 = 30
 endif    

 if switch>=20 then
 x3 = x3+1
 y3 = 30
 endif
 
 if switch=30 then
 switch=0
 endif 
 gosub piksel
 next
    
for i = 1 to 300
switch=switch+1  

 if switch<=3 then
 x4 = x4+9
 y4 = 45
 endif    

 if switch>=20 then
 x4 = x4+1
 endif
 
 if switch=25 then
 switch=0
 endif

 gosub piksel
 next
 

 SwapBuffers()
 End     

 piksel:
 glBegin(GL_POINTS)
 glVertex2f(x1 + 100, y1 +150)
 glVertex2f(x2 + 100, y2 +150)
 glVertex2f(x3 + 100, y3 +150) 
 glVertex2f(x4 + 100, y4 +150)
 glEnd()
 return

Hasil Run Program :