/**
 * @brief   Test the collision by the "hot" texture
 * @author  XadillaX
 * @email   admin@xcoder.in
 * @date    2011/10/18
 * @http://xcoder.in
 *
 * @param spr1 The first sprite to test the collision
 * @param x1 "x" of top-left corner of sprite 1
 * @param y1 "y" of top-left corner of sprite 1
 * @param spr2 The second sprite to test the collision
 * @param x2 "x" of top-left corner of sprite 2
 * @param y2 "y" of top-left corner of sprite 2
 * @param hot1 The "hot" texture for sprite 1. It will be the default texture of spr1 if it equal to 0
 * @param hot2 The "hot" texture for sprite 2. It will be the default texture of spr2 if it equal to 0
 * @param airColor The color which considered of "air"
 *
 * @return if they are collided, return true
 */
bool IsCollision(hgeSprite* spr1, float x1, float y1, hgeSprite* spr2, float x2, float y2, HTEXTURE hot1 = 0, HTEXTURE hot2 = 0, DWORD airColor = 0xffff00ff)
{
    /** Set the rect */
    hgeRect r1, r2;
    r1.Set(x1, y1, x1 + spr1->GetWidth(), y1 + spr1->GetHeight());
    r2.Set(x2, y2, x2 + spr2->GetWidth(), y2 + spr2->GetHeight());

    /** Test for the intersect of rectangles */
    if(r1.Intersect(&r2))
    {
        int x[] = { x1, x2, x1 + spr1->GetWidth(), x2 + spr2->GetWidth() };
        int y[] = { y1, y2, y1 + spr1->GetHeight(), y2 + spr2->GetHeight() };
        std::sort(x, x + 4);
        std::sort(y, y + 4);
        hgeRect r;

        /** Set the rectangle area where the two rectangles intersected. */
        r.Set(x[1], y[1], x[2], y[2]);

        /** The start point of sprite1 and sprite2. (From the intersected area) */
        int sx1, sy1, sx2, sy2;
        sx1 = x[1] - x1;
        sy1 = y[1] - y1;
        sx2 = x[1] - x2;
        sy2 = y[1] - y2;

        /** Get the "hotspot" of texture */
        HTEXTURE hTex1 = hot1;
        HTEXTURE hTex2 = hot2;
        if(hTex1 == 0) hTex1 = spr1->GetTexture();
        if(hTex2 == 0) hTex2 = spr2->GetTexture();

        float tx1, ty1, tw1, th1, tx2, ty2, tw2, th2;
        int w1 = hge->Texture_GetWidth(hTex1), w2 = hge->Texture_GetWidth(hTex2);
        spr1->GetTextureRect(&tx1, &ty1, &tw1, &th1);
        spr2->GetTextureRect(&tx2, &ty2, &tw2, &th2);

        DWORD* color1 = new DWORD[(x[2] - x[1]) * (y[2] - y[1])];
        DWORD* color2 = new DWORD[(x[2] - x[1]) * (y[2] - y[1])];
        DWORD* color;

        /** Copy the effectivearea of texture 1 */
        color = hge->Texture_Lock(hTex1, true);
        for(int i = 0; i < y[2] - y[1]; i++)
        {
            for(int j = 0; j < x[2] - x[1]; j++)
            { 
                color1[i * (x[2] - x[1]) + j] = color[((int)ty1 + sy1) * w1 + (int)tx1 + sx1 + i * w1 + j];
            } 
        } 
        hge->Texture_Unlock(hTex1);

        /** Copy the effectivearea of texture 2 */
        color = hge->Texture_Lock(hTex2, true);
        for(int i = 0; i < y[2] - y[1]; i++)
        {
            for(int j = 0; j < x[2] - x[1]; j++) 
            { 
                color2[i * (x[2] - x[1]) + j] = color[((int)ty2 + sy2) * w2 + (int)tx2 + sx2 + i * w1 + j]; 
            } 
        } 
        hge->Texture_Unlock(hTex2);

        /** Test for the collision */
        for(int i = 0; i < y[2] - y[1]; i++)
        {
            for(int j = 0; j < x[2] - x[1]; j++)
            {
                if(color1[i * (x[2] - x[1]) + j] != airColor && color2[i * (x[2] - x[1]) + j] != airColor)
                {
                    delete []color1;
                    delete []color2;

                    return true;
                }
            }
        }

        delete []color1;
        delete []color2;
        return false;
    }
    else return false;
}