// Scale2x scaler.

uniform sampler2D tex;

uniform sampler2D videoTex;

varying vec2 texStep; // could be uniform

varying vec2 coord2pi;

varying vec2 texCoord;

varying vec2 videoCoord;

vec4 scaleNx()

{

	vec4 delta;

	delta.xw = sin(coord2pi) * texStep;

	delta.yz = vec2(0.0);

	vec4 posLeftTop  = texCoord.stst - delta;

	vec4 posRightBot = texCoord.stst + delta;

	vec4 left  = texture2D(tex, posLeftTop.xy);

	vec4 top   = texture2D(tex, posLeftTop.zw);

	vec4 right = texture2D(tex, posRightBot.xy);

	vec4 bot   = texture2D(tex, posRightBot.zw);

	if (dot(left.rgb - right.rgb, top.rgb - bot.rgb) == 0.0 || left.rgb != top.rgb) {

		return texture2D(tex, texCoord.st);

	} else {

		return top;

	}

}

void main()

{

#if SUPERIMPOSE

	vec4 col = scaleNx();

	vec4 vid = texture2D(videoTex, videoCoord);

	gl_FragColor = mix(vid, col, col.a);

#else

	gl_FragColor = scaleNx();

#endif

}