void BrushMaskGenerator::buildLUT(const Brush &brush)
{
// First, determine if the brush shape depends on pressure
_usepressure =
brush.radius1() != brush.radius2() ||
qAbs(brush.hardness1() - brush.hardness2()) >= (1/256.0) ||
qAbs(brush.opacity1() - brush.opacity2()) >= (1/256.0)
;
if(_usepressure) {
// Build a lookup table for all pressure levels
uint len = 0;
_index.reserve(PRESSURE_LEVELS + 1);
_radius.reserve(PRESSURE_LEVELS);
_index.append(0);
for(int i=0;i<PRESSURE_LEVELS;++i) {
float p = int2pressure(i);
float radius = brush.fradius(p);
_radius.append(radius);
len += ceil(radius*radius);
_index.append(len);
}
_lut.resize(len);
for(int i=0;i<PRESSURE_LEVELS;++i) {
float p = int2pressure(i);
_buildLUT(_radius.at(i), brush.opacity(p), brush.hardness(p), _index.at(i+1)-_index.at(i), _lut.data() + _index.at(i));
}
} else {
// Shape not affected by pressure: only lookup table needed
float radius = brush.fradius(1.0);
int len = ceil(radius*radius);
_lut.resize(len);
_index.append(len);
_radius.append(radius);
_buildLUT(radius, brush.opacity1(), brush.hardness1(), len, _lut.data());
}
}
