DBL image_pattern(const Vector3d& EPoint, const BasicPattern* pPattern)
{
DBL xcoor = 0.0, ycoor = 0.0;
int index = -1;
RGBFTColour colour;
const ImageData *image = dynamic_cast<const ImagePatternImpl*>(pPattern)->pImage;
DBL Value;
colour.Clear();
// going to have to change this
// need to know if bump point is off of image for all 3 points
if(map_pos(EPoint, pPattern, &xcoor, &ycoor))
return 0.0;
else
image_colour_at(image, xcoor, ycoor, colour, &index); // TODO ALPHA - we should decide whether we prefer premultiplied or non-premultiplied alpha
if((index == -1) || image->Use)
{
if(image->Use == USE_ALPHA)
{
// use alpha channel or red channel
if(image->data->HasTransparency() == true)
Value = colour.transm();
else
Value = colour.red(); // otherwise, just use the red channel
}
else
// use grey-scaled version of the color
Value = colour.Greyscale();
}
else
Value = index / 255.0;
if(Value < 0)
Value = 0;
else if(Value > 1.0)
Value = 1.0;
return Value;
}
static void InterpolateBicubic(const ImageData *image, DBL xcoor, DBL ycoor, RGBFTColour& colour, int *index, bool premul)
{
int iycoor, ixcoor;
int cornerIndex;
RGBFTColour cornerColour;
DBL factor;
DBL factorsX[4];
DBL factorsY[4];
xcoor += 0.5;
ycoor += 0.5;
iycoor = (int)ycoor;
ixcoor = (int)xcoor;
cubic(factorsX, xcoor);
cubic(factorsY, ycoor);
// We're using double precision for the colors here to avoid higher-than-1.0 results due to rounding errors,
// which would otherwise lead to stray dot artifacts when clamped to [0..1] range for a color_map or similar.
// (Note that strictly speaking we don't avoid such rounding errors, but rather make them small enough that
// subsequent rounding to single precision will take care of them.)
// (Note that bicubic interpolation may still give values outside the range [0..1] at high-contrast edges;
// this is an inherent property of this interpolation method, and is therefore accepted here.)
PreciseRGBFTColour tempColour;
DBL tempIndex = 0;
for (int i = 0; i < 4; i ++)
{
for (int j = 0; j < 4; j ++)
{
cornerColour.Clear();
no_interpolation(image, (DBL)ixcoor + i-2, (DBL)iycoor + j-2, cornerColour, &cornerIndex, premul);
factor = factorsX[i] * factorsY[j];
tempColour += PreciseRGBFTColour(cornerColour) * factor;
tempIndex += cornerIndex * factor;
}
}
colour = RGBFTColour(tempColour);
*index = (int)tempIndex;
}