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.

C
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>
- 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>
C#
C# example using the OpenTK library, which is multiplatform and provides C# OpenGL bindings for .Net and Mono. This code creates it's own window and draws the triangle into it.
<lang csharp> using OpenTK; using OpenTK.Graphics; namespace OpenGLTest {
class Program { static void Main(string[] args) { //Create the OpenGL window GameWindow window = new GameWindow(640, 480, GraphicsMode.Default, "OpenGL Example");
GL.MatrixMode(MatrixMode.Projection); GL.LoadIdentity(); GL.Ortho(-30.0, 30.0, -30.0, 30.0, -30.0, 30.0); GL.MatrixMode(MatrixMode.Modelview);
//Add event handler to render to the window when called window.RenderFrame += new RenderFrameEvent(a_RenderFrame); //Starts the window's updating/rendering events window.Run(); } static void a_RenderFrame(GameWindow sender, RenderFrameEventArgs e) { GL.ClearColor(0.3f, 0.3f, 0.3f, 0f); GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
GL.ShadeModel(ShadingModel.Smooth);
GL.LoadIdentity(); GL.Translate(-15.0f, -15.0f, 0.0f);
GL.Begin(BeginMode.Triangles); GL.Color3(1.0f, 0.0f, 0.0f); GL.Vertex2(0.0f, 0.0f); GL.Color3(0.0f, 1.0f, 0.0f); GL.Vertex2(30f, 0.0f); GL.Color3(0.0f, 0.0f, 1.0f); GL.Vertex2(0.0f, 30.0f); GL.End(); //Swaps the buffers on the window so that what we draw becomes visible sender.SwapBuffers(); } }
} </lang>
D
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
triangle.fs: <lang forth> import glconst import float
glconst also float also opengl also</lang>
triangle.m: <lang forth> #! 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</lang>
Haskell
<lang 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)</lang>
J
<lang J>coclass 'example' (coinsert[require) 'jzopengl'
create=:3 :0
ogl=: conew'jzopengl' wd 'pc p; xywh 0 0 320 240;cc c isigraph opengl rightmove bottommove;' wd 'pas 6 6;pshow;'
)
p_close=: destroy=:3 :0
destroy__ogl wd'pclose' codestroy
)
corner=:4 :0
glColor3d x glVertex2d y
)
p_c_paint=:3 :0
rc__ogl glClear GL_COLOR_BUFFER_BIT glBegin GL_TRIANGLES 1 0 0 corner 0 0-0.5 0 1 0 corner 1 0-0.5 0 0 1 corner 0 1-0.5 glEnd show__ogl
)
conew~'example'</lang>
Note: OpenGL's initial state is well defined by the OpenGL standard.
MAXScript
The choice of OpenGL or D3D in MAX is a user configuration setting. All MAXScript code is platform independent. <lang maxscript> 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</lang>
OCaml
<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
<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;</lang>
<lang perl> 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; }, });</lang>
Python
<lang 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()
</lang>
R
<lang R> library(rgl) x <- c(-1, -1, 1) y <- c(0, -1, -1) z <- c(0, 0, 0) M <- cbind(x,y,z) rgl.bg(color="gray15") triangles3d(M, col=rainbow(8)) </lang>
Tcl
Also requires the tcl3d package. <lang Tcl>package require Tk package require tcl3d
proc resizedWin {win w h} {
glViewport 0 0 $w $h glMatrixMode GL_PROJECTION glLoadIdentity glOrtho -30.0 30.0 -30.0 30.0 -30.0 30.0 glMatrixMode GL_MODELVIEW
} proc paintShape {win} {
glClearColor 0.0 0.0 0.0 0.5 glClear [expr {$::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 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 $win swapbuffers
}
togl .surface -width 640 -height 480 -double true -depth true \
-displayproc paintShape -reshapeproc resizedWin
pack .surface -fill both -expand 1</lang>Most of this code should be very familiar to anyone looking at the C version above, or with normal Tk applications.