QTS no. 23 - Primitive rectangle and line gradients

/*
-----------------------------------------
* Game hacking QTS ( Quickie Tip Series )
* no. 23 - Primitive rectangle and line gradients
-----------------------------------------
* Author: SEGnosis  - GHAnon.net
* Thanks to:
* bitterbanana      - No known site
* Drunken Cheetah   - No known site
* fatboy88      - No known site
* Geek4Ever         - No known site
* learn_more        - www.uc-forum.com
* Novocaine         - http://ilsken.net/blog/?page_id=64
* Philly0494        - No known site
* Roverturbo        - www.uc-forum.com
* SilentKarma       - www.halocoders.com - offline
* Strife        - www.uc-forum.com
* Wieter20      - No known site
*/

struct FVect3
{
    float x, y, z;
};

struct FVect2
{
    float x, y;
};

struct FTrigFunc
{
    float   sine,
        cosine,
        tangent,
        hypotenuse,
        radian;
};



void GradientRect( D3DXVECTOR2 vPos, int iWidth, int iHeight, D3DCOLOR coA, D3DCOLOR coB )
{
    CDraw.Rect( vPos.x, vPos.y, iWidth, iHeight, coA );

    S_D3DCOLOR* pColor = ( S_D3DCOLOR* )&coB;

    pColor->a = 0;

    float fRateY = 255 / iHeight;

    for( int i = 0; i < iHeight; i++ )
    {
        CDraw.Rect( vPos.x, vPos.y + i, iWidth, 1, coB );

        pColor->a = min( 255, pColor->a + fRateY );
    }
}

void GradientLine( D3DXVECTOR2 vPosA, D3DXVECTOR2 vPosB, D3DCOLOR coA, D3DCOLOR coB, DWORD dwWidth = 1 )
{
    S_D3DCOLOR* pColor = ( S_D3DCOLOR* )&coB;

    FTrigFunc vTrig;

    // get total distance and quadrent
    FVect2 vDistance = { vPosA.x - vPosB.x + 0.000001f, vPosA.y - vPosB.y + 0.000001f };

    // get trig stats
    vTrig.hypotenuse    = CAimbot.VectToHypot( vDistance ) + 0.000001f;
    vTrig.radian        = acosf( ( vDistance.y ) / vTrig.hypotenuse );

    // offset based on quadrent
    if( vDistance.x < 0 && vDistance.y < 0 || vDistance.x < 0 && vDistance.y > 0 ) // in quad 2 - 3
        vTrig.radian    = ( PI - vTrig.radian );
    else
        vTrig.radian    = ( PI + vTrig.radian );

    // Ratio to offset by
    vTrig.cosine = cosf( vTrig.radian );
    vTrig.sine   = sinf( vTrig.radian );


    // Rate that alpha should increase ( must be float or max line distance is 255 D: )
    float   fRateY = 255 / abs( vTrig.hypotenuse ),
            fAlpha = 0;

    // Set alpha to 0
    pColor->a = 0;

    // Start second line from first line
    D3DXVECTOR2 vPosC = vPosA;

    // Draw Underlying Line
    CDraw.Line( vPosA.x, vPosA.y, vPosB.x, vPosB.y, dwWidth, coA );

    // Draw overlying line with increasing alpha channel
    for( float i = 0; i < vTrig.hypotenuse; i++ )
    {
        // Draw line from position to second position
        CDraw.Line( vPosC.x, vPosC.y, vPosC.x + vTrig.sine, vPosC.y + vTrig.cosine, dwWidth, coB );

        // Offset by ratio
        vPosC.x += vTrig.sine;
        vPosC.y += vTrig.cosine;

        // Increase alpha
        if( fAlpha + fRateY < 255.0000f )
            fAlpha += fRateY;

        // set alpha
        pColor->a = fAlpha;
    }
}