//
//This shader implements super-sampled anti-aliasing.
//

varying vec2 texcoord;

#ifdef VERTEX_SHADER
attribute vec2 v_texcoord;
void main()
{
	texcoord = v_texcoord.xy;
	texcoord.y = 1.0 - texcoord.y;
	gl_Position = ftetransform();
}
#endif
#ifdef FRAGMENT_SHADER
uniform sampler2D s_t0;
uniform vec2 e_sourcesize;

void main( void )
{
	float FXAA_SPAN_MAX = 8.0;
	float FXAA_REDUCE_MUL = 1.0/8.0;
	float FXAA_REDUCE_MIN = 1.0/128.0;

	vec3 rgbNW=texture2D(s_t0,texcoord+(vec2(-1.0,-1.0)/e_sourcesize)).xyz;
	vec3 rgbNE=texture2D(s_t0,texcoord+(vec2(1.0,-1.0)/e_sourcesize)).xyz;
	vec3 rgbSW=texture2D(s_t0,texcoord+(vec2(-1.0,1.0)/e_sourcesize)).xyz;
	vec3 rgbSE=texture2D(s_t0,texcoord+(vec2(1.0,1.0)/e_sourcesize)).xyz;
	vec3 rgbM=texture2D(s_t0,texcoord).xyz;

	vec3 luma=vec3(0.299, 0.587, 0.114);
	float lumaNW = dot(rgbNW, luma);
	float lumaNE = dot(rgbNE, luma);
	float lumaSW = dot(rgbSW, luma);
	float lumaSE = dot(rgbSE, luma);
	float lumaM  = dot(rgbM,  luma);

	float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));
	float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));

	vec2 dir;
	dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));
	dir.y =  ((lumaNW + lumaSW) - (lumaNE + lumaSE));

	float dirReduce = max((lumaNW + lumaNE + lumaSW + lumaSE) * (0.25 * FXAA_REDUCE_MUL), FXAA_REDUCE_MIN);

	float rcpDirMin = 1.0/(min(abs(dir.x), abs(dir.y)) + dirReduce);

	dir = min(vec2( FXAA_SPAN_MAX,  FXAA_SPAN_MAX),
	max(vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX),
	dir * rcpDirMin)) / e_sourcesize;

	vec3 rgbA = (1.0/2.0) * (texture2D(s_t0, texcoord.xy + dir * (1.0/3.0 - 0.5)).xyz +	texture2D(s_t0, texcoord.xy + dir * (2.0/3.0 - 0.5)).xyz);
	vec3 rgbB = rgbA * (1.0/2.0) + (1.0/4.0) * (texture2D(s_t0, texcoord.xy + dir * (0.0/3.0 - 0.5)).xyz + texture2D(s_t0, texcoord.xy + dir * (3.0/3.0 - 0.5)).xyz);
	float lumaB = dot(rgbB, luma);

	if((lumaB < lumaMin) || (lumaB > lumaMax))
		gl_FragColor.xyz=rgbA;
	else
		gl_FragColor.xyz=rgbB;
	gl_FragColor.a = 1.0;
}
#endif