OpenGL

OpenGL
You are encouraged to solve this task according to the task description, using any language you may know.

In this task, the goal is to display a smooth shaded triangle with OpenGL.

Triangle created using C example compiled with GCC 4.1.2 and freeglut3.

C

Works with: gcc version 3.3.3

Library: GLUT

In this example, we use GLUT to create a window and handle the main loop in a portable way. Windowing systems like MS Windows and X11 have their own platform-specific ways of handling these things.

<lang c>#include<GL/gl.h>

1. include<GL/glut.h>

void paint(void) { glClearColor(0.3,0.3,0.3,0.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glShadeModel(GL_SMOOTH);

glLoadIdentity(); glTranslatef(-15.0, -15.0, 0.0);

glBegin(GL_TRIANGLES); glColor3f(1.0, 0.0, 0.0); glVertex2f(0.0, 0.0); glColor3f(0.0, 1.0, 0.0); glVertex2f(30.0, 0.0); glColor3f(0.0, 0.0, 1.0); glVertex2f(0.0, 30.0); glEnd();

glFlush(); }

void reshape(int width, int height) { glViewport(0, 0, width, height); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-30.0, 30.0, -30.0, 30.0, -30.0, 30.0); glMatrixMode(GL_MODELVIEW); }

int main(int argc, char *argv[]) { glutInit(&argc, argv); glutInitWindowSize(640, 480); glutCreateWindow("Triangle");

glutDisplayFunc(paint); glutReshapeFunc(reshape);

glutMainLoop();

return 0; }</lang>

D

Works with: GDC

Works with: DMD

Library: dglut

opengl_sample.d: <lang d>module opengl_sample; // file name + directory import dglut.core, dglut.window, dglut.opengl;

void main() {

 with (new Canvas) {
   setName("Triangle");
   map;

   onResize = (Canvas self) { // A delegate literal that takes a parameter.
     with (self) glViewport(0, 0, width, height);
     MatrixMode.Projection.Identity; // For functions without parameters, the () can be omitted.
     glOrtho(-30, 30, -30, 30, -30, 30);
     MatrixMode.Modelview;
   };

   onDisplay=(Canvas self) {
     scope(exit) self.swap; // Scope guards ease exception-safe programming
     glClearColor(0.3f, 0.3f, 0.3f, 0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     glLoadIdentity;
     // A convenience wrapper around glTranslatef. Supports numbers, arrays and vectors.
     Translate(-15, -15, 0);
     // This is a delegate literal as well. Triangles is a wrapper around glBegin and glEnd.
     Triangles = {
       Color(1f, 0f, 0f); Vertex(0, 0);
       Color(0f, 1f, 0f); Vertex(30, 0);
       Color(0f, 0f, 1f); Vertex(0, 30);
     };
   };
 }
 loop;

} </lang>

Forth

Works with: bigFORTH

Library: MINOS

Library: Theseus

triangle.fs:

import glconst import float
glconst also float also opengl also

triangle.m:

#! xbigforth
\ automatic generated code
\ do not edit

also editor also minos also forth

include triangle.fs
component class triangle
public:
  early widget
  early open
  early dialog
  early open-app
 ( [varstart] )  ( [varend] )
how:
  : open     new DF[ 0 ]DF s" Triangle" open-component ;
  : dialog   new DF[ 0 ]DF s" Triangle" open-dialog ;
  : open-app new DF[ 0 ]DF s" Triangle" open-application ;
class;

triangle implements
 ( [methodstart] )  ( [methodend] )
  : widget  ( [dumpstart] )
        GL[ ^ glcanvas with
0 0 w @ h @ glViewport
GL_PROJECTION glMatrixMode
glLoadIdentity
-30e 30e -30e 30e -30e 30e glOrtho
GL_MODELVIEW glMatrixMode
0.3e 0.3e 0.3e 0.0e glClearColor
GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT or glClear
GL_SMOOTH glShadeModel
glLoadIdentity
-15e -15e 0e glTranslatef
GL_TRIANGLES glBegin
1e 0e 0e glColor3f
0e 0e glVertex2f
0e 1e 0e glColor3f
30e 0e glVertex2f
0e 0e 1e glColor3f
0e 30e glVertex2f
glEnd 
glFlush
endwith ]GL ( MINOS ) ^^ CK[ ( x y b n -- ) 2drop 2drop ]CK ( MINOS ) $280 $1 *hfil $1E0 $1 *vfil glcanvas new
      &1 vabox new
    ( [dumpend] ) ;
  : init  ^>^^  assign  widget 1 :: init ;
class;

: main
  triangle open-app
  $1 0 ?DO  stop  LOOP bye ;
script? [IF]  main  [THEN]
previous previous previous

Haskell

import Graphics.Rendering.OpenGL
import Graphics.UI.GLUT

main = do
  getArgsAndInitialize
   createWindow "Triangle"
  displayCallback $= display
      
  matrixMode $= Projection
  loadIdentity
  ortho2D 0 30 0 30
  matrixMode $= Modelview 0
  
  mainLoop

display = do
  clear [ColorBuffer]
  renderPrimitive Triangles $ do
    corner 1 0 0 5 5
    corner 0 1 0 25 5
    corner 0 0 1 5 25
  swapBuffers
       
corner r g b x y = do color  (Color3  r g b :: Color3  GLfloat)
                      vertex (Vertex2 x y   :: Vertex2 GLfloat)

MAXScript

The choice of OpenGL or D3D in MAX is a user configuration setting. All MAXScript code is platform independent.

newMesh = mesh numVerts:3 numFaces:1
setMesh newMesh vertices:#([-100, -100, 0], [100, -100, 0], [-100, 100, 0]) faces:#([1, 2, 3])
defaultVCFaces newMesh
setVertColor newMesh 1 red
setVertColor newMesh 2 green
setVertColor newMesh 3 blue
setCVertMode newMesh true
update newMesh
viewport.setType #view_top
max tool maximize
viewport.SetRenderLevel #smoothhighlights

OCaml

Library: glMLite

<lang ocaml>open GL open Glut

let display() =

 glClearColor 0.3 0.3 0.3 0.0;
 glClear[GL_COLOR_BUFFER_BIT; GL_DEPTH_BUFFER_BIT];

 glShadeModel GL_SMOOTH;

 glLoadIdentity();
 glTranslate (-15.0) (-15.0) (0.0);

 glBegin GL_TRIANGLES;
 glColor3 1.0 0.0 0.0;
 glVertex2 0.0 0.0;
 glColor3 0.0 1.0 0.0;
 glVertex2 30.0 0.0;
 glColor3 0.0 0.0 1.0;
 glVertex2 0.0 30.0;
 glEnd();

 glFlush();

let reshape ~width ~height =

 glViewport 0 0 width height;
 glMatrixMode GL_PROJECTION;
 glLoadIdentity();
 glOrtho(-30.0) 30.0 (-30.0) 30.0 (-30.0) 30.0;
 glMatrixMode GL_MODELVIEW;

let () =

 ignore(glutInit Sys.argv);
 glutInitWindowSize 640 480;
 ignore(glutCreateWindow "Triangle");

 glutDisplayFunc ~display;
 glutReshapeFunc ~reshape;

 glutMainLoop();

</lang>

Perl

use OpenGL;

sub triangle {
    glBegin GL_TRIANGLES;
    glColor3f 1.0, 0.0, 0.0;
    glVertex2f 5.0, 5.0;
    glColor3f 0.0, 1.0, 0.0;
    glVertex2f 25.0, 5.0;
    glColor3f 0.0, 0.0, 1.0;
    glVertex2f 5.0, 25.0;
    glEnd;
};

glpOpenWindow;
glMatrixMode GL_PROJECTION;
glLoadIdentity;
gluOrtho2D 0.0, 30.0, 0.0, 30.0;
glMatrixMode GL_MODELVIEW;

glClear GL_COLOR_BUFFER_BIT;
triangle;
glpFlush;

glpMainLoop;

Library: SDL

use SDL::App;
use SDL::Event;
use SDL::OpenGL;

$app = SDL::App->new(
  -gl => 1,
);

sub triangle {
  glBegin(GL_TRIANGLES);
  glColor(1.0, 0.0, 0.0);
  glVertex(5.0, 5.0);
  glColor(0.0, 1.0, 0.0);
  glVertex(25.0, 5.0);
  glColor(0.0, 0.0, 1.0);
  glVertex(5.0, 25.0);
  glEnd();
}

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0.0, 30.0, 0.0, 30.0);
glMatrixMode(GL_MODELVIEW);
glClear(GL_COLOR_BUFFER_BIT);
triangle();
$app->sync;
$app->loop ({
  SDL_QUIT() => sub { exit; },
});

Python

#-*- coding: utf8 -*-

from OpenGL.GL import *
from OpenGL.GLUT import *

def paint():
    glClearColor(0.3,0.3,0.3,0.0)
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

    glShadeModel(GL_SMOOTH)

    glLoadIdentity()
    glTranslatef(-15.0, -15.0, 0.0)

    glBegin(GL_TRIANGLES)
    glColor3f(1.0, 0.0, 0.0)
    glVertex2f(0.0, 0.0)
    glColor3f(0.0, 1.0, 0.0)
    glVertex2f(30.0, 0.0)
    glColor3f(0.0, 0.0, 1.0)
    glVertex2f(0.0, 30.0)
    glEnd()

    glFlush()

def reshape(width, height):
    glViewport(0, 0, width, height)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    glOrtho(-30.0, 30.0, -30.0, 30.0, -30.0, 30.0)
    glMatrixMode(GL_MODELVIEW)

if __name__ == '__main__':
    glutInit(1, 1)
    glutInitWindowSize(640, 480)
    glutCreateWindow("Triangle")

    glutDisplayFunc(paint)
    glutReshapeFunc(reshape)

    glutMainLoop()