using System;

using OpenTK.Graphics.OpenGL;

namespace org.niclasundharald.engine.graphics
{
	public class GlobalDefaults
	{
		private static GlobalDefaults _instance = new GlobalDefaults();
		public static GlobalDefaults instance(){
			return _instance;
		}

		private Shader defVertexShader,
					defFragmentShader;
		private ShaderProgram
					defShaderProgram;

		private GLSceneOrientation activeScene;

		private GlobalDefaults(){

			Console.WriteLine("GlobalDefaults: Shader Version: {0}", GL.GetString(StringName.ShadingLanguageVersion));

			defVertexShader = new Shader(OpenTK.Graphics.OpenGL.ShaderType.VertexShader, defVertexShaderSource);
			defFragmentShader = new Shader(OpenTK.Graphics.OpenGL.ShaderType.FragmentShader, defFragmentShaderSource);

			defShaderProgram = new ShaderProgram(defVertexShader, defFragmentShader);

			activeScene = new GLSceneOrientation();
		}

		public ShaderProgram DefaultShaderProgram {
			get { return this.defShaderProgram;}
		}

		public Shader DefaultVertexShader
		{
			get { return defVertexShader; }
		}

		public Shader DefaultFragmentShader
		{
			get { return defFragmentShader; }
		}

		public GLSceneOrientation ActiveScene {
			get { return this.activeScene; }
			set { this.activeScene = value; }
		}


private string defVertexShaderSource = @"#version 330
  
layout(location = 0) in vec3 iv_position;
layout(location = 1) in vec4 iv_color;
layout(location = 2) in vec3 iv_normal;
layout(location = 3) in vec4 iv_col2;
layout(location = 4) in vec2 iv_uv;

uniform mat4 mObject;
uniform mat4 mCamera;
uniform mat4 mObjectCamera;
uniform mat4 mObjectCameraIT;
uniform mat4 mProjection;
uniform mat4 mScene;

out vec4 color;
out vec3 norm;
out vec2 uv;
out vec3 coord;

out float	shading;

void main()
{
			gl_Position = mScene * vec4( iv_position, 1 );

	float	fading	= 1.0;
	
			norm	= normalize( ( mObjectCameraIT * vec4( iv_normal    , 1 ) ).xyz );
	vec3 	camray	= (mObjectCamera   * vec4( iv_position  , 1 )).xyz;
	vec3 	ncamray	= normalize( camray );

	float	cosTheta = abs( clamp(dot( norm , ncamray ), -1, 1) );
	float	distance = length(camray);
	float	idist = 25000 / distance;
	float	sight = clamp( idist * idist * idist, 0.1, 1.0);

			shading = clamp(0.3 + (cosTheta * 0.7), 0.1, 0.9) * sight;
			color = clamp( vec4( iv_color.xyz, fading ) * iv_col2, 0, 1);
			coord	= camray;
}

";
		
private string defFragmentShaderSource = @"#version 330

in vec4 color;
in vec3 norm;
in vec2 uv;
in vec3 coord;

in float shading;

out vec4 _color;

void main()
{
	float cosTheta = dot( -coord, norm );
	
	if (cosTheta >= 0){
		discard;
	};

    _color = vec4( color.xyz * shading, color.w );
	//_color = vec4( (vec3( 1,1,1 ) + norm)/2 , 1 );
}

";


	}

}