basic.frag

uniform sampler2D texture;

void main()
{
    vec4 pixel = texture2D(texture, gl_TexCoord[0].st);
	gl_FragColor = gl_Color * pixel;
}

basic.vert

//gl_Position = ftransform();

void main()
{
    gl_Position = ftransform();
	gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
	gl_FrontColor = gl_Color;
}

Program.cs

using System;
using System.Diagnostics;
using System.IO;

using SFML.Graphics;
using SFML.Window;
using Color = SFML.Graphics.Color;

namespace ArxGame
{

	public static class Program
	{
		private static readonly Color CornflowerBlue = new Color( 100, 149, 237 );

		public static void Main(string[] args)
		{
			RenderWindow window = new RenderWindow( new VideoMode( 800, 600 ), "SFML Window" );
			window.SetVerticalSyncEnabled( true );
			window.Closed += (sender, eventArgs) => window.Close();

			Texture texture = new Texture( "media/dude.png" );
			Sprite _spr = new Sprite( texture );

			uint tWidth = texture.Size.X;
			uint tHeight = texture.Size.Y;
			Vertex v1 = new Vertex( new Vector2f( 0, 0 ) );
			Vertex v2 = new Vertex( new Vector2f( tWidth, 0 ) );
			Vertex v3 = new Vertex( new Vector2f( tWidth, tHeight ) );
			Vertex v4 = new Vertex( new Vector2f( 0, tHeight ) );

			v1.TexCoords = new Vector2f( 0, 0 );
			v2.TexCoords = new Vector2f( tWidth, 0 );
			v3.TexCoords = new Vector2f( tWidth, tHeight );
			v4.TexCoords = new Vector2f( 0, tHeight );

			VertexArray varr = new VertexArray( PrimitiveType.Quads );
			varr.Append( v1 );
			varr.Append( v2 );
			varr.Append( v3 );
			varr.Append( v4 );


			Shader shader = new Shader( "media/shaders/basic.vert", "media/shaders/basic.frag" );
			shader.SetParameter( "texture", texture );
			RenderStates rState = new RenderStates( shader );
			

			while ( window.IsOpen() )
			{
				window.DispatchEvents();
				window.Clear(CornflowerBlue);

				window.Draw( varr, rState );

				window.Display();
			}
		}
	}
}