/*------------------------------------------------------------------------
 *
 * OpenVG 1.1 Reference Implementation
 * -----------------------------------
 *
 * Copyright (c) 2007 The Khronos Group Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and /or associated documentation files
 * (the "Materials "), to deal in the Materials without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Materials,
 * and to permit persons to whom the Materials are furnished to do so,
 * subject to the following conditions: 
 *
 * The above copyright notice and this permission notice shall be included 
 * in all copies or substantial portions of the Materials. 
 *
 * THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE MATERIALS OR
 * THE USE OR OTHER DEALINGS IN THE MATERIALS.
 *
 *//**
 * \file
 * \brief   Implementation of Paint and pixel pipe functionality.
 * \note    
 *//*-------------------------------------------------------------------*/

#include "riPixelPipe.h"

//==============================================================================================

namespace OpenVGRI
{

/*-------------------------------------------------------------------*//*!
* \brief    Paint constructor.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

Paint::Paint() :
    m_paintType(VG_PAINT_TYPE_COLOR),
    m_paintColor(0,0,0,1,Color::sRGBA_PRE),
    m_inputPaintColor(0,0,0,1,Color::sRGBA),
    m_colorRampSpreadMode(VG_COLOR_RAMP_SPREAD_PAD),
    m_colorRampStops(),
    m_inputColorRampStops(),
    m_colorRampPremultiplied(VG_TRUE),
    m_inputLinearGradientPoint0(0,0),
    m_inputLinearGradientPoint1(1,0),
    m_inputRadialGradientCenter(0,0),
    m_inputRadialGradientFocalPoint(0,0),
    m_inputRadialGradientRadius(1.0f),
    m_linearGradientPoint0(0,0),
    m_linearGradientPoint1(1,0),
    m_radialGradientCenter(0,0),
    m_radialGradientFocalPoint(0,0),
    m_radialGradientRadius(1.0f),
    m_patternTilingMode(VG_TILE_FILL),
    m_pattern(NULL),
    m_referenceCount(0)
{
    Paint::GradientStop gs;
    gs.offset = 0.0f;
    gs.color.set(0,0,0,1,Color::sRGBA);
    m_colorRampStops.push_back(gs); //throws bad_alloc
    gs.offset = 1.0f;
    gs.color.set(1,1,1,1,Color::sRGBA);
    m_colorRampStops.push_back(gs); //throws bad_alloc
}

/*-------------------------------------------------------------------*//*!
* \brief    Paint destructor.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

Paint::~Paint()
{
    RI_ASSERT(m_referenceCount == 0);
    if(m_pattern)
    {
        m_pattern->removeInUse();
        if(!m_pattern->removeReference())
            RI_DELETE(m_pattern);
    }
}

/*-------------------------------------------------------------------*//*!
* \brief    PixelPipe constructor.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

PixelPipe::PixelPipe() :
    m_drawable(NULL),
    m_image(NULL),
    m_paint(NULL),
    m_defaultPaint(),
    m_blendMode(VG_BLEND_SRC_OVER),
    m_imageMode(VG_DRAW_IMAGE_NORMAL),
    m_imageQuality(VG_IMAGE_QUALITY_FASTER),
    m_tileFillColor(0,0,0,0,Color::sRGBA),
    m_colorTransform(false),
    m_colorTransformValues(),
    m_surfaceToPaintMatrix(),
    m_surfaceToImageMatrix()
{
    for(int i=0;i<8;i++)
        m_colorTransformValues[i] = (i < 4) ? 1.0f : 0.0f;
}

/*-------------------------------------------------------------------*//*!
* \brief    PixelPipe destructor.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

PixelPipe::~PixelPipe()
{
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the rendering surface.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setDrawable(Drawable* drawable)
{
    RI_ASSERT(drawable);
    m_drawable = drawable;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the blend mode.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setBlendMode(VGBlendMode blendMode)
{
    RI_ASSERT(blendMode >= VG_BLEND_SRC && blendMode <= VG_BLEND_ADDITIVE);
    m_blendMode = blendMode;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the mask image. NULL disables masking.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setMask(bool masking)
{
    m_masking = masking;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the image to be drawn. NULL disables image drawing.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setImage(Image* image, VGImageMode imageMode)
{
    RI_ASSERT(imageMode == VG_DRAW_IMAGE_NORMAL || imageMode == VG_DRAW_IMAGE_MULTIPLY || imageMode == VG_DRAW_IMAGE_STENCIL);
    m_image = image;
    m_imageMode = imageMode;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the surface-to-paint matrix.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setSurfaceToPaintMatrix(const Matrix3x3& surfaceToPaintMatrix)
{
    m_surfaceToPaintMatrix = surfaceToPaintMatrix;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets the surface-to-image matrix.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setSurfaceToImageMatrix(const Matrix3x3& surfaceToImageMatrix)
{
    m_surfaceToImageMatrix = surfaceToImageMatrix;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets image quality.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setImageQuality(VGImageQuality imageQuality)
{
    RI_ASSERT(imageQuality == VG_IMAGE_QUALITY_NONANTIALIASED || imageQuality == VG_IMAGE_QUALITY_FASTER || imageQuality == VG_IMAGE_QUALITY_BETTER);
    m_imageQuality = imageQuality;
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets fill color for VG_TILE_FILL tiling mode (pattern only).
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setTileFillColor(const Color& c)
{
    m_tileFillColor = c;
    m_tileFillColor.clamp();
}

/*-------------------------------------------------------------------*//*!
* \brief    Sets paint.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setPaint(const Paint* paint)
{
    m_paint = paint;
    if(!m_paint)
        m_paint = &m_defaultPaint;
    if(m_paint->m_pattern)
        m_tileFillColor.convert(m_paint->m_pattern->getDescriptor().internalFormat);
}

/*-------------------------------------------------------------------*//*!
* \brief    Color transform.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::setColorTransform(bool enable, RIfloat values[8])
{
    m_colorTransform = enable;
    for(int i=0;i<4;i++)
    {
        m_colorTransformValues[i] = RI_CLAMP(values[i], -127.0f, 127.0f);
        m_colorTransformValues[i+4] = RI_CLAMP(values[i+4], -1.0f, 1.0f);
    }
}

/*-------------------------------------------------------------------*//*!
* \brief    Computes the linear gradient function at (x,y).
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::linearGradient(RIfloat& g, RIfloat& rho, RIfloat x, RIfloat y) const
{
    RI_ASSERT(m_paint);
    Vector2 u = m_paint->m_linearGradientPoint1 - m_paint->m_linearGradientPoint0;
    RIfloat usq = dot(u,u);
    if( usq <= 0.0f )
    {   //points are equal, gradient is always 1.0f
        g = 1.0f;
        rho = 0.0f;
        return;
    }
    RIfloat oou = 1.0f / usq;

    Vector2 p(x, y);
    p = affineTransform(m_surfaceToPaintMatrix, p);
    p -= m_paint->m_linearGradientPoint0;
    RI_ASSERT(usq >= 0.0f);
    g = dot(p, u) * oou;
    RIfloat dgdx = oou * u.x * m_surfaceToPaintMatrix[0][0] + oou * u.y * m_surfaceToPaintMatrix[1][0];
    RIfloat dgdy = oou * u.x * m_surfaceToPaintMatrix[0][1] + oou * u.y * m_surfaceToPaintMatrix[1][1];
    rho = (RIfloat)sqrt(dgdx*dgdx + dgdy*dgdy);
    RI_ASSERT(rho >= 0.0f);
}

/*-------------------------------------------------------------------*//*!
* \brief    Computes the radial gradient function at (x,y).
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

void PixelPipe::radialGradient(RIfloat &g, RIfloat &rho, RIfloat x, RIfloat y) const
{
    RI_ASSERT(m_paint);
    if( m_paint->m_radialGradientRadius <= 0.0f )
    {
        g = 1.0f;
        rho = 0.0f;
        return;
    }

    RIfloat r = m_paint->m_radialGradientRadius;
    Vector2 c = m_paint->m_radialGradientCenter;
    Vector2 f = m_paint->m_radialGradientFocalPoint;
    Vector2 gx(m_surfaceToPaintMatrix[0][0], m_surfaceToPaintMatrix[1][0]);
    Vector2 gy(m_surfaceToPaintMatrix[0][1], m_surfaceToPaintMatrix[1][1]);

    Vector2 fp = f - c;

    //clamp the focal point inside the gradient circle
    RIfloat fpLen = fp.length();
    if( fpLen > 0.999f * r )
        fp *= 0.999f * r / fpLen;

    RIfloat D = -1.0f / (dot(fp,fp) - r*r);
    Vector2 p(x, y);
    p = affineTransform(m_surfaceToPaintMatrix, p) - c;
    Vector2 d = p - fp;
    RIfloat s = (RIfloat)sqrt(r*r*dot(d,d) - RI_SQR(p.x*fp.y - p.y*fp.x));
    g = (dot(fp,d) + s) * D;
    if(RI_ISNAN(g))
        g = 0.0f;
    RIfloat dgdx = D*dot(fp,gx) + (r*r*dot(d,gx) - (gx.x*fp.y - gx.y*fp.x)*(p.x*fp.y - p.y*fp.x)) * (D / s);
    RIfloat dgdy = D*dot(fp,gy) + (r*r*dot(d,gy) - (gy.x*fp.y - gy.y*fp.x)*(p.x*fp.y - p.y*fp.x)) * (D / s);
    rho = (RIfloat)sqrt(dgdx*dgdx + dgdy*dgdy);
    if(RI_ISNAN(rho))
        rho = 0.0f;
    RI_ASSERT(rho >= 0.0f);
}

/*-------------------------------------------------------------------*//*!
* \brief    Returns the average color within an offset range in the color ramp.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

static Color readStopColor(const Array<Paint::GradientStop>& colorRampStops, int i, VGboolean colorRampPremultiplied)
{
    RI_ASSERT(i >= 0 && i < colorRampStops.size());
    Color c = colorRampStops[i].color;
    RI_ASSERT(c.getInternalFormat() == Color::sRGBA);
    if(colorRampPremultiplied)
        c.premultiply();
    return c;
}

Color PixelPipe::integrateColorRamp(RIfloat gmin, RIfloat gmax) const
{
    RI_ASSERT(gmin <= gmax);
    RI_ASSERT(gmin >= 0.0f && gmin <= 1.0f);
    RI_ASSERT(gmax >= 0.0f && gmax <= 1.0f);
    RI_ASSERT(m_paint->m_colorRampStops.size() >= 2);   //there are at least two stops

    Color c(0,0,0,0,m_paint->m_colorRampPremultiplied ? Color::sRGBA_PRE : Color::sRGBA);
    if(gmin == 1.0f || gmax == 0.0f)
        return c;

    int i=0;
    for(;i<m_paint->m_colorRampStops.size()-1;i++)
    {
        if(gmin >= m_paint->m_colorRampStops[i].offset && gmin < m_paint->m_colorRampStops[i+1].offset)
        {
            RIfloat s = m_paint->m_colorRampStops[i].offset;
            RIfloat e = m_paint->m_colorRampStops[i+1].offset;
            RI_ASSERT(s < e);
            RIfloat g = (gmin - s) / (e - s);

            Color sc = readStopColor(m_paint->m_colorRampStops, i, m_paint->m_colorRampPremultiplied);
            Color ec = readStopColor(m_paint->m_colorRampStops, i+1, m_paint->m_colorRampPremultiplied);
            Color rc = (1.0f-g) * sc + g * ec;

            //subtract the average color from the start of the stop to gmin
            c -= 0.5f*(gmin - s)*(sc + rc);
            break;
        }
    }

    for(;i<m_paint->m_colorRampStops.size()-1;i++)
    {
        RIfloat s = m_paint->m_colorRampStops[i].offset;
        RIfloat e = m_paint->m_colorRampStops[i+1].offset;
        RI_ASSERT(s <= e);

        Color sc = readStopColor(m_paint->m_colorRampStops, i, m_paint->m_colorRampPremultiplied);
        Color ec = readStopColor(m_paint->m_colorRampStops, i+1, m_paint->m_colorRampPremultiplied);

        //average of the stop
        c += 0.5f*(e-s)*(sc + ec);

        if(gmax >= m_paint->m_colorRampStops[i].offset && gmax < m_paint->m_colorRampStops[i+1].offset)
        {
            RIfloat g = (gmax - s) / (e - s);
            Color rc = (1.0f-g) * sc + g * ec;

            //subtract the average color from gmax to the end of the stop
            c -= 0.5f*(e - gmax)*(rc + ec);
            break;
        }
    }
    return c;
}

/*-------------------------------------------------------------------*//*!
* \brief    Maps a gradient function value to a color.
* \param    
* \return   
* \note     
*//*-------------------------------------------------------------------*/

Color PixelPipe::colorRamp(RIfloat gradient, RIfloat rho) const
{
    RI_ASSERT(m_paint);
    RI_ASSERT(rho >= 0.0f);

    Color c(0,0,0,0,m_paint->m_colorRampPremultiplied ? Color::sRGBA_PRE : Color::sRGBA);
    Color avg;

    if(rho == 0.0f)
    {   //filter size is zero or gradient is degenerate
        switch(m_paint->m_colorRampSpreadMode)
        {
        case VG_COLOR_RAMP_SPREAD_PAD:
            gradient = RI_CLAMP(gradient, 0.0f, 1.0f);
            break;
        case VG_COLOR_RAMP_SPREAD_REFLECT:
        {
            RIfloat g = RI_MOD(gradient, 2.0f);
            gradient = (g < 1.0f) ? g : 2.0f - g;
            break;
        }
        default:
            RI_ASSERT(m_paint->m_colorRampSpreadMode == VG_COLOR_RAMP_SPREAD_REPEAT);
            gradient = gradient - (RIfloat)floor(gradient);
            break;
        }
        RI_ASSERT(gradient >= 0.0f && gradient <= 1.0f);

        for(int i=0;i<m_paint->m_colorRampStops.size()-1;i++)
        {
            if(gradient >= m_paint->m_colorRampStops[i].offset && gradient < m_paint->m_colorRampStops[i+1].offset)
            {
                RIfloat s = m_paint->m_colorRampStops[i].offset;
                RIfloat e = m_paint->m_colorRampStops[i+1].offset;
                RI_ASSERT(s < e);
                RIfloat g = RI_CLAMP((gradient - s) / (e - s), 0.0f, 1.0f); //clamp needed due to numerical inaccuracies

                Color sc = readStopColor(m_paint->m_colorRampStops, i, m_paint->m_colorRampPremultiplied);
                Color ec = readStopColor(m_paint->m_colorRampStops, i+1, m_paint->m_colorRampPremultiplied);
                return (1.0f-g) * sc + g * ec;  //return interpolated value
            }
        }
        return readStopColor(m_paint->m_colorRampStops, m_paint->m_colorRampStops.size()-1, m_paint->m_colorRampPremultiplied);
    }

    RIfloat gmin = gradient - rho*0.5f;         //filter starting from the gradient point (if starts earlier, radial gradient center will be an average of the first and the last stop, which doesn't look good)
    RIfloat gmax = gradient + rho*0.5f;

    switch(m_paint->m_colorRampSpreadMode)
    {
    case VG_COLOR_RAMP_SPREAD_PAD:
    {
        if(gmin < 0.0f)
            c += (RI_MIN(gmax, 0.0f) - gmin) * readStopColor(m_paint->m_colorRampStops, 0, m_paint->m_colorRampPremultiplied);
        if(gmax > 1.0f)
            c += (gmax - RI_MAX(gmin, 1.0f)) * readStopColor(m_paint->m_colorRampStops, m_paint->m_colorRampStops.size()-1, m_paint->m_colorRampPremultiplied);
        gmin = RI_CLAMP(gmin, 0.0f, 1.0f);
        gmax = RI_CLAMP(gmax, 0.0f, 1.0f);
        c += integrateColorRamp(gmin, gmax);
        c *= 1.0f/rho;
        c.clamp();  //clamp needed due to numerical inaccuracies
        return c;
    }

    case VG_COLOR_RAMP_SPREAD_REFLECT:
    {
        avg = integrateColorRamp(0.0f, 1.0f);
        RIfloat gmini = (RIfloat)floor(gmin);
        RIfloat gmaxi = (RIfloat)floor(gmax);
        c = (gmaxi + 1.0f - gmini) * avg;       //full ramps

        //subtract beginning
        if(((int)gmini) & 1)
            c -= integrateColorRamp(RI_CLAMP(1.0f - (gmin - gmini), 0.0f, 1.0f), 1.0f);
        else
            c -= integrateColorRamp(0.0f, RI_CLAMP(gmin - gmini, 0.0f, 1.0f));

        //subtract end
        if(((int)gmaxi) & 1)
            c -= integrateColorRamp(0.0f, RI_CLAMP(1.0f - (gmax - gmaxi), 0.0f, 1.0f));
        else
            c -= integrateColorRamp(RI_CLAMP(gmax - gmaxi, 0.0f, 1.0f), 1.0f);
        break;
    }

    default:
    {
        RI_ASSERT(m_paint->m_colorRampSpreadMode == VG_COLOR_RAMP_SPREAD_REPEAT);
        avg = integrateColorRamp(0.0f, 1.0f);
        RIfloat gmini = (RIfloat)floor(gmin);
        RIfloat gmaxi = (RIfloat)floor(gmax);
        c = (gmaxi + 1.0f - gmini) * avg;       //full ramps
        c -= integrateColorRamp(0.0f, RI_CLAMP(gmin - gmini, 0.0f, 1.0f));  //subtract beginning
        c -= integrateColorRamp(RI_CLAMP(gmax - gmaxi, 0.0f, 1.0f), 1.0f);  //subtract end
        break;
    }
    }

    //divide color by the length of the range
    c *= 1.0f / rho;
    c.clamp();  //clamp needed due to numerical inaccuracies

    //hide aliasing by fading to the average color
    const RIfloat fadeStart = 0.5f;
    const RIfloat fadeMultiplier = 2.0f;    //the larger, the earlier fade to average is done

    if(rho < fadeStart)
        return c;

    RIfloat ratio = RI_MIN((rho - fadeStart) * fadeMultiplier, 1.0f);
    return ratio * avg + (1.0f - ratio) * c;
}

/*-------------------------------------------------------------------*//*!
* \brief    Computes blend.
* \param    
* \return   
* \note     premultiplied blending formulas
            //src
            a = asrc
            r = rsrc
            //src over
            a = asrc + adst * (1-asrc)
            r = rsrc + rdst * (1-asrc)
            //dst over
            a = asrc * (1-adst) + adst
            r = rsrc * (1-adst) + adst
            //src in
            a = asrc * adst
            r = rsrc * adst
            //dst in
            a = adst * asrc
            r = rdst * asrc
            //multiply
            a = asrc + adst * (1-asrc)
            r = rsrc * (1-adst) + rdst * (1-asrc) + rsrc * rdst
            //screen
            a = asrc + adst * (1-asrc)
            r = rsrc + rdst - rsrc * rdst
            //darken
            a = asrc + adst * (1-asrc)
            r = MIN(rsrc + rdst * (1-asrc), rdst + rsrc * (1-adst))
            //lighten
            a = asrc + adst * (1-asrc)
            r = MAX(rsrc + rdst * (1-asrc), rdst + rsrc * (1-adst))
            //additive
            a = MIN(asrc+adst,1)
            r = rsrc + rdst
*//*-------------------------------------------------------------------*/

Color PixelPipe::blend(const Color& s, RIfloat ar, RIfloat ag, RIfloat ab, const Color& d, VGBlendMode blendMode) const
{
    //apply blending in the premultiplied format
    Color r(0,0,0,0,d.getInternalFormat());
    RI_ASSERT(s.a >= 0.0f && s.a <= 1.0f);
    RI_ASSERT(s.r >= 0.0f && s.r <= s.a && s.r <= ar);
    RI_ASSERT(s.g >= 0.0f && s.g <= s.a && s.g <= ag);
    RI_ASSERT(s.b >= 0.0f && s.b <= s.a && s.b <= ab);
    RI_ASSERT(d.a >= 0.0f && d.a <= 1.0f);
    RI_ASSERT(d.r >= 0.0f && d.r <= d.a);
    RI_ASSERT(d.g >= 0.0f && d.g <= d.a);
    RI_ASSERT(d.b >= 0.0f && d.b <= d.a);
    switch(blendMode)
    {
    case VG_BLEND_SRC:
        r = s;
        break;

    case VG_BLEND_SRC_OVER:
        r.r = s.r + d.r * (1.0f - ar);
        r.g = s.g + d.g * (1.0f - ag);
        r.b = s.b + d.b * (1.0f - ab);
        r.a = s.a + d.a * (1.0f - s.a);
        break;

    case VG_BLEND_DST_OVER:
        r.r = s.r * (1.0f - d.a) + d.r;
        r.g = s.g * (1.0f - d.a) + d.g;
        r.b = s.b * (1.0f - d.a) + d.b;
        r.a = s.a * (1.0f - d.a) + d.a;
        break;

    case VG_BLEND_SRC_IN:
        r.r = s.r * d.a;
        r.g = s.g * d.a;
        r.b = s.b * d.a;
        r.a = s.a * d.a;
        break;

    case VG_BLEND_DST_IN:
        r.r = d.r * ar;
        r.g = d.g * ag;
        r.b = d.b * ab;
        r.a = d.a * s.a;
        break;

    case VG_BLEND_MULTIPLY:
        r.r = s.r * (1.0f - d.a + d.r) + d.r * (1.0f - ar);
        r.g = s.g * (1.0f - d.a + d.g) + d.g * (1.0f - ag);
        r.b = s.b * (1.0f - d.a + d.b) + d.b * (1.0f - ab);
        r.a = s.a + d.a * (1.0f - s.a);
        break;

    case VG_BLEND_SCREEN:
        r.r = s.r + d.r * (1.0f - s.r);
        r.g = s.g + d.g * (1.0f - s.g);
        r.b = s.b + d.b * (1.0f - s.b);
        r.a = s.a + d.a * (1.0f - s.a);
        break;

    case VG_BLEND_DARKEN:
        r.r = RI_MIN(s.r + d.r * (1.0f - ar), d.r + s.r * (1.0f - d.a));
        r.g = RI_MIN(s.g + d.g * (1.0f - ag), d.g + s.g * (1.0f - d.a));
        r.b = RI_MIN(s.b + d.b * (1.0f - ab), d.b + s.b * (1.0f - d.a));
        r.a = s.a + d.a * (1.0f - s.a);
        break;

    case VG_BLEND_LIGHTEN:
        r.r = RI_MAX(s.r + d.r * (1.0f - ar), d.r + s.r * (1.0f - d.a));
        r.g = RI_MAX(s.g + d.g * (1.0f - ag), d.g + s.g * (1.0f - d.a));
        r.b = RI_MAX(s.b + d.b * (1.0f - ab), d.b + s.b * (1.0f - d.a));
        //although the statement below is equivalent to r.a = s.a + d.a * (1.0f - s.a)
        //in practice there can be a very slight difference because
        //of the max operation in the blending formula that may cause color to exceed alpha.
        //Because of this, we compute the result both ways and return the maximum.
        r.a = RI_MAX(s.a + d.a * (1.0f - s.a), d.a + s.a * (1.0f - d.a));
        break;

    default:
        RI_ASSERT(blendMode == VG_BLEND_ADDITIVE);
        r.r = RI_MIN(s.r + d.r, 1.0f);
        r.g = RI_MIN(s.g + d.g, 1.0f);
        r.b = RI_MIN(s.b + d.b, 1.0f);
        r.a = RI_MIN(s.a + d.a, 1.0f);
        break;
    }
    return r;
}

/*-------------------------------------------------------------------*//*!
* \brief    Applies color transform.
* \param    
* \return   
* \note
*//*-------------------------------------------------------------------*/

void PixelPipe::colorTransform(Color& c) const
{
    if(m_colorTransform)
    {
        c.unpremultiply();
        c.luminanceToRGB();
        c.r = c.r * m_colorTransformValues[0] + m_colorTransformValues[4];
        c.g = c.g * m_colorTransformValues[1] + m_colorTransformValues[5];
        c.b = c.b * m_colorTransformValues[2] + m_colorTransformValues[6];
        c.a = c.a * m_colorTransformValues[3] + m_colorTransformValues[7];
        c.clamp();
        c.premultiply();
    }
}

/*-------------------------------------------------------------------*//*!
* \brief    Applies paint, image drawing, masking and blending at pixel (x,y).
* \param    
* \return   
* \note
*//*-------------------------------------------------------------------*/

void PixelPipe::pixelPipe(int x, int y, RIfloat coverage, unsigned int sampleMask) const
{
    RI_ASSERT(m_drawable);
    RI_ASSERT(sampleMask);
    RI_ASSERT(coverage > 0.0f);
    Color::InternalFormat dstFormat = (Color::InternalFormat)(m_drawable->getDescriptor().internalFormat | Color::PREMULTIPLIED);

    //evaluate paint
    RI_ASSERT(m_paint);
    Color s;
    switch(m_paint->m_paintType)
    {
    case VG_PAINT_TYPE_COLOR:
        s = m_paint->m_paintColor;
        break;

    case VG_PAINT_TYPE_LINEAR_GRADIENT:
    {
        RIfloat g, rho;
        linearGradient(g, rho, x+0.5f, y+0.5f);
        s = colorRamp(g, rho);
        RI_ASSERT((s.getInternalFormat() == Color::sRGBA && !m_paint->m_colorRampPremultiplied) || (s.getInternalFormat() == Color::sRGBA_PRE && m_paint->m_colorRampPremultiplied));
        s.premultiply();
        break;
    }

    case VG_PAINT_TYPE_RADIAL_GRADIENT:
    {
        RIfloat g, rho;
        radialGradient(g, rho, x+0.5f, y+0.5f);
        s = colorRamp(g, rho);
        RI_ASSERT((s.getInternalFormat() == Color::sRGBA && !m_paint->m_colorRampPremultiplied) || (s.getInternalFormat() == Color::sRGBA_PRE && m_paint->m_colorRampPremultiplied));
        s.premultiply();
        break;
    }

    default:
        RI_ASSERT(m_paint->m_paintType == VG_PAINT_TYPE_PATTERN);
        if(m_paint->m_pattern)
            s = m_paint->m_pattern->resample(x+0.5f, y+0.5f, m_surfaceToPaintMatrix, m_imageQuality, m_paint->m_patternTilingMode, m_tileFillColor);
        else
            s = m_paint->m_paintColor;
        break;
    }
    s.assertConsistency();

    //apply image (vgDrawImage only)
    //1. paint: convert paint to dst space
    //2. image: convert image to dst space
    //3. paint MULTIPLY image: convert paint to image number of channels, multiply with image, and convert to dst
    //4. paint STENCIL image: convert paint to dst, convert image to dst number of channels, multiply

    //color transform:
    //paint => transform paint color
    //image normal => transform image color
    //image multiply => transform paint*image color
    //image stencil => transform paint color

    RIfloat ar = 0.0f, ag = 0.0f, ab = 0.0f;
    if(m_image)
    {
        Color im = m_image->resample(x+0.5f, y+0.5f, m_surfaceToImageMatrix, m_imageQuality, VG_TILE_PAD, Color(0,0,0,0,m_image->getDescriptor().internalFormat));
        im.assertConsistency();

        switch(m_imageMode)
        {
        case VG_DRAW_IMAGE_NORMAL:
            s = im;
            colorTransform(s);
            ar = s.a;
            ag = s.a;
            ab = s.a;
            s.convert(dstFormat);   //convert image color to destination color space
            break;
        case VG_DRAW_IMAGE_MULTIPLY:
            //the result will be in image color space, except when paint is RGB and image is L the result will be RGB.
            //paint == RGB && image == RGB: RGB*RGB
            //paint == RGB && image == L  : RGB*LLL
            //paint == L   && image == RGB: LLL*RGB
            //paint == L   && image == L  : L*L
            RI_ASSERT(m_surfaceToPaintMatrix.isAffine());
            if(!s.isLuminance() && im.isLuminance())
                im.convert((Color::InternalFormat)(im.getInternalFormat() & ~Color::LUMINANCE));
            im.r *= s.r;
            im.g *= s.g;
            im.b *= s.b;
            im.a *= s.a;
            s = im;     //use image color space
            colorTransform(s);
            ar = s.a;
            ag = s.a;
            ab = s.a;
            s.convert(dstFormat);   //convert resulting color to destination color space
            break;
        default:
            //the result will be in paint color space.
            //dst == RGB && image == RGB: RGB*RGB
            //dst == RGB && image == L  : RGB*LLL
            //dst == L   && image == RGB: L*(0.2126 R + 0.7152 G + 0.0722 B)
            //dst == L   && image == L  : L*L
            RI_ASSERT(m_imageMode == VG_DRAW_IMAGE_STENCIL);
            if(dstFormat & Color::LUMINANCE && !im.isLuminance())
            {
                im.r = im.g = im.b = RI_MIN(0.2126f*im.r + 0.7152f*im.g + 0.0722f*im.b, im.a);
            }
            RI_ASSERT(m_surfaceToPaintMatrix.isAffine());
            //s and im are both in premultiplied format. Each image channel acts as an alpha channel.
            colorTransform(s);
            s.convert(dstFormat);   //convert paint color to destination space already here, since convert cannot deal with per channel alphas used in this mode.
            //compute per channel alphas
            ar = s.a * im.r;
            ag = s.a * im.g;
            ab = s.a * im.b;
            //premultiply each channel by per channel alphas from the image
            s.r *= im.r;
            s.g *= im.g;
            s.b *= im.b;
            s.a *= im.a;
            //in nonpremultiplied form the result is
            // s.rgb = paint.a * paint.rgb * image.a * image.rgb
            // s.a = paint.a * image.a
            // argb = paint.a * image.a * image.rgb
            break;
        }
    }
    else
    {    //paint only
        colorTransform(s);
        ar = s.a;
        ag = s.a;
        ab = s.a;
        s.convert(dstFormat);   //convert paint color to destination color space
    }
    RI_ASSERT(s.getInternalFormat() == Color::lRGBA_PRE || s.getInternalFormat() == Color::sRGBA_PRE || s.getInternalFormat() == Color::lLA_PRE || s.getInternalFormat() == Color::sLA_PRE);
    s.assertConsistency();

    Surface* colorBuffer = m_drawable->getColorBuffer();
    Surface* maskBuffer = m_drawable->getMaskBuffer();
    RI_ASSERT(colorBuffer);

    if(m_drawable->getNumSamples() == 1)
    {   //coverage-based antialiasing
        RIfloat cov = coverage;
        if(m_masking && maskBuffer)
        {
            cov *= maskBuffer->readMaskCoverage(x, y);
            if(cov == 0.0f)
                return;
        }

        //read destination color
        Color d = colorBuffer->readSample(x, y, 0);
        d.premultiply();
        RI_ASSERT(dstFormat == Color::lRGBA_PRE || dstFormat == Color::sRGBA_PRE || dstFormat == Color::lLA_PRE || dstFormat == Color::sLA_PRE);

        //blend
        Color r = blend(s, ar, ag, ab, d, m_blendMode);

        //apply antialiasing in linear color space
        Color::InternalFormat aaFormat = (dstFormat & Color::LUMINANCE) ? Color::lLA_PRE : Color::lRGBA_PRE;
        r.convert(aaFormat);
        d.convert(aaFormat);
        r = r * cov + d * (1.0f - cov);

        //write result to the destination surface
        r.convert(colorBuffer->getDescriptor().internalFormat);
        colorBuffer->writeSample(x, y, 0, r);
    }
    else
    {   //multisampling FSAA
        if(m_masking && maskBuffer)
        {
            sampleMask &= maskBuffer->readMaskMSAA(x, y);
            if(!sampleMask)
                return;
        }

        {
            for(int i=0;i<m_drawable->getNumSamples();i++)
            {
                if(sampleMask & (1<<i)) //1-bit coverage
                {
                    //read destination color
                    Color d = colorBuffer->readSample(x, y, i);

                    d.premultiply();
                    RI_ASSERT(dstFormat == Color::lRGBA_PRE || dstFormat == Color::sRGBA_PRE || dstFormat == Color::lLA_PRE || dstFormat == Color::sLA_PRE);

                    //blend
                    Color r = blend(s, ar, ag, ab, d, m_blendMode);

                    //write result to the destination surface
                    r.convert(colorBuffer->getDescriptor().internalFormat);
                    colorBuffer->writeSample(x, y, i, r);
                }
            }
        }
    }
}

//=======================================================================
    
}   //namespace OpenVGRI