//uniform vec3 g_ConversionWeights;


varying vec4 ambient, diffuse;
varying vec3 normal, lightdir, halfvector;

//uniform sampler2D tex, hello;

void main()
{
	float NdotL, NdotHV, gray;
	vec3  n     = normalize(normal);
	vec4 // texcolor = texture2D(tex, gl_TexCoord[0].st),
	      fragcolor = ambient,
	      color;
	
	//compute the dot pruduct of the normalized normal and light direction
	NdotL = max(dot(n, lightdir), 0.0);
	
	if (NdotL > 0.0)
	{
		//add diffuse light component
		fragcolor += diffuse * NdotL;
		
		//compute the dot product of the normal and half vector (of the lightdir and eye position)
		NdotHV = max(dot(n, halfvector), 0.0);
		
		fragcolor += gl_FrontMaterial.specular * gl_LightSource[0].specular * 
					 pow(NdotHV, gl_FrontMaterial.shininess);
	}
	
	
	
	//modulate the fragment color with the texel color for the final color
//	color = texcolor * fragcolor;
	color = fragcolor;
	
	//smoothstep not available on ati motbility 8600
	//color += smoothstep(1.0,0.2,NdotL) * texture2D(hello, gl_TexCoord[0].st);
	
	//convert to grayscale using NTSC conversion weights 
	gray = dot(color.rgb, vec3(0.299, 0.587, 0.114));
	//gray = dot(color.rgb, g_ConversionWeights);
	//gray = color.r * 0.299 + color.g * 0.587 + color.b * 0.114;

	//copy grayscale to rgb components and use the alpha from the final color
	gl_FragColor = vec4(gray, gray, gray, color.a);
	
	// convert grayscale to sepia
    //gl_FragColor = vec4(gray * vec3(1.2, 1.0, 0.8), color.a);
}