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

Compiler: gcc 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.

#include<GL/gl.h>
#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;
}

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

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
This is an example of a library. You may see a list of other libraries used on Rosetta Code at Category:Solutions by Library.

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()

MINOS

Using 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]
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