# OpenGL example using glut

import opengl/glut
import opengl
import opengl/glu

proc display() {.cdecl.} =
  glClear(GL_COLOR_BUFFER_BIT)
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()                 # Reset the model-view matrix

  glBegin(GL_TRIANGLES)        # Begin drawing of triangles

  glColor3f(0.0, 1.0, 0.0)
  glVertex3f( -0.5, -0.5, 0.0)
  glColor3f(1.0, 0.0, 0.0)
  glVertex3f(0, 0.5, 0.0)
  glColor3f(0.0, 0.0, 1.0)
  glVertex3f(0.5, -0.5, 0.0)

  glEnd()  # End of drawing

  glutSwapBuffers() # Swap the front and back frame buffers (double buffering)

var argc: cint = 0
glutInit()

glutInitDisplayMode(GLUT_DOUBLE)
glutInitWindowSize(640, 480)
glutInitWindowPosition(50, 50)
discard glutCreateWindow("Modern OpenGL Example")

glutDisplayFunc(display)

loadExtensions()

glClearColor(0.0, 0.0, 0.0, 1.0)                   # Set background color to black and opaque

glutMainLoop()