//
// blisteringly erotic 9slice drawing tool.
//
varying vec2 v_vTexcoord;
varying vec4 v_vColour;
uniform sampler2D s_tex;
uniform float u_width;
uniform float u_height;
uniform float u_tileDim;
uniform float u_offset;

uniform float u_originX;
uniform float u_originY;



void main()
{
    //This is for UV correction down the line.
    //60.0 is a magic number, the width of the texture
    float halfTexelOffset = 1.0/60.0/2.0;
    float texelWidth = 1.0/60.0;
    //float minUV = halfTexelOffset;
    float maxUV = 1.0 - texelWidth;
    //ALGORITHM!
    //1. DO everything at once, gloriously.
    float X = floor(gl_FragCoord.x) - u_originX;
    float Y = floor(gl_FragCoord.y) - u_originY;

    vec2 realPos = vec2(X,Y);
    vec2 texUV = vec2(0.0,0.0);


    //X-axis
    if (realPos.x <= u_tileDim)
    {
        texUV.x = mix(0.0,maxUV, (realPos.x / u_tileDim) / 3.0);
        texUV.x += halfTexelOffset;
    }
    else if (realPos.x >= (u_width - u_tileDim))
    {

        texUV.x = mix(0.0,maxUV, (2.0 + (realPos.x - (u_width - u_tileDim)) / u_tileDim) / 3.0);
        texUV.x += halfTexelOffset;
    }
    else
    {
        texUV.x = ( 1.0 + mod(realPos.x,u_tileDim) / u_tileDim) / 3.0; //YES FIX THIS ONE TOO
        texUV.x = mix(0.0,maxUV,texUV.x);
        texUV.x += halfTexelOffset;//no, that's not enough. It needs to be in the right range already.
        //texUV -= texelWidth * floor(u_width / u_tileDim);
    }

    //Y-axis
    if (realPos.y <= u_tileDim)
    {

        texUV.y = mix(0.0,maxUV, (realPos.y / u_tileDim) / 3.0);
        texUV.y += halfTexelOffset;
    }
    else if (realPos.y >= (u_height- u_tileDim))
    {
        texUV.y = mix(0.0,maxUV, (2.0 + (realPos.y - (u_height- u_tileDim)) / u_tileDim) / 3.0);
        texUV.y += halfTexelOffset;
    }
    else
    {
        texUV.y = ( 1.0 + mod(realPos.y,u_tileDim) / u_tileDim) / 3.0; //YES FIX THIS ONE TOO
        texUV.y = mix(0.0,maxUV,texUV.y);
        texUV.y += halfTexelOffset;//no, that's not enough. It needs to be in the right range already.
    }

    //THe above calculations give us UVs that fall on gridlines in the sprite.
    //We need to sample the middle of the texels instead
    //float halfTexelOffset = 1.0/u_tileDim/2.0; //WORKS BEST WITH .05

    texUV.x += u_offset * halfTexelOffset;
    texUV.y += u_offset * halfTexelOffset;

    //And some extra correction

    {
        gl_FragColor = texture2D( s_tex, texUV);
    }

    if ((clamp(texUV.x, 0.0, 1.0) < texUV.x) || (clamp(texUV.y, 0.0, 1.0) < texUV.y))
    {
        //discard;
    }
    //if (texUV.x <= halfTexelOffset * 2.0)
    //{
    //  gl_FragColor = vec4(255.0,255.0,0.0,255.0);
    //}

    //if (texUV.y >= 1.0 - (halfTexelOffset * 2.0))
    //{
    //  gl_FragColor = vec4(255.0,255.0,0.0,255.0);
    //}
}