//UVTranslator.h
//Author: Adam Hulbert - hulbert.adam@gmail.com
//Use: translates row and column position into a float[4] of UV coordinates

#pragma once

#include <string>

class UVTranslator
{
public:
    //CTOR
    //float width_      : width of the entire spritesheet image
    //float height_     : height of the entire spritesheet image
    //float blockWidth_ : the width of each sprite in the sprite sheet (will only work when sprite sheets have equally spaced sprites),
    //float blockHeight_    : the height of each sprite in the sprite sheet (will only work when sprite sheets have equally spaced sprites), if 0, defaults to blockWidth_;
    UVTranslator(float width_, float height_, float blockWidth_, float blockHeight_);

    //default ctor, object is in an invalid state until Init is called.
    UVTranslator();

    //calls the matching CTOR
    void Init(float sheetWidth_, float sheetHeight_, float tileWidth_, float tileHeight_);

    //float* out_       : must be a float array initialised with 4 elements.
    //float col_        : 0 based column (starting from left)
    //float row_        : 0 based row (starting from the bottom)
    //float blockCols_  : number of columns to retreive in the UV (defaults to 1)
    //float rowWidth_   : number of rows to retreive in the UV (defaults to 1)
    void GetUV(float* out_, float row_, float col_, float tileCols_ = 1, float tileRows_ = 1);

    ~UVTranslator();

private:

    float tileWidth;
    float tileHeight;
    float sheetWidth;
    float sheetHeight;
};

//UVTranslator.cpp
#include "UVTranslator.h"

UVTranslator::UVTranslator(float width_, float height_, float tileWidth_, float tileHeight_)
    : sheetWidth(width_), sheetHeight(height_), tileWidth(tileWidth_), tileHeight(tileHeight_)
{
}

//needs to be initialised still after default ctor
UVTranslator::UVTranslator(void)
{
}


UVTranslator::~UVTranslator(void)
{
}

void UVTranslator::Init(float width_, float height_, float tileWidth_, float tileHeight_)
{
    sheetWidth = width_;
    sheetHeight = height_;
    tileWidth = tileWidth_;
    tileHeight = tileHeight_;
}


void UVTranslator::GetUV(float* out_, float row_, float col_, float blockCols_, float blockRows_)
{
    //{ U_MIN , V_MIN , U_MIN + U_STEP, V_MIN + V_STEP };
    out_[0] = col_ * tileWidth / sheetWidth;
    out_[1] = row_ * tileHeight / sheetHeight;
    out_[2] = out_[0] + ((blockCols_ * tileWidth)/sheetWidth);
    out_[3] = out_[1] + ((blockRows_ * tileHeight)/sheetHeight);
}