float rand_gauss (RngDouble * rng)
{
double sum = 0.0;
sum += rng_double_next(rng);
sum += rng_double_next(rng);
sum += rng_double_next(rng);
sum += rng_double_next(rng);
return sum * 1.73205080757 - 3.46410161514;
}
// This function runs a brush "simulation" step. Usually it is
// called once or twice per dab. In theory the precision of the
// "simulation" gets better when it is called more often. In
// practice this only matters if there are some highly nonlinear
// mappings in critical places or extremely few events per second.
//
// note: parameters are is dx/ddab, ..., dtime/ddab (dab is the number, 5.0 = 5th dab)
void update_states_and_setting_values (MyPaintBrush *self, float step_ddab, float step_dx, float step_dy, float step_dpressure, float step_declination, float step_ascension, float step_dtime)
{
float pressure;
float inputs[MYPAINT_BRUSH_INPUTS_COUNT];
if (step_dtime < 0.0) {
printf("Time is running backwards!\n");
step_dtime = 0.001;
} else if (step_dtime == 0.0) {
// FIXME: happens about every 10th start, workaround (against division by zero)
step_dtime = 0.001;
}
self->states[MYPAINT_BRUSH_STATE_X] += step_dx;
self->states[MYPAINT_BRUSH_STATE_Y] += step_dy;
self->states[MYPAINT_BRUSH_STATE_PRESSURE] += step_dpressure;
self->states[MYPAINT_BRUSH_STATE_DECLINATION] += step_declination;
self->states[MYPAINT_BRUSH_STATE_ASCENSION] += step_ascension;
float base_radius = expf(mypaint_mapping_get_base_value(self->settings[MYPAINT_BRUSH_SETTING_RADIUS_LOGARITHMIC]));
// FIXME: does happen (interpolation problem?)
if (self->states[MYPAINT_BRUSH_STATE_PRESSURE] <= 0.0) self->states[MYPAINT_BRUSH_STATE_PRESSURE] = 0.0;
pressure = self->states[MYPAINT_BRUSH_STATE_PRESSURE];
{ // start / end stroke (for "stroke" input only)
if (!self->states[MYPAINT_BRUSH_STATE_STROKE_STARTED]) {
if (pressure > mypaint_mapping_get_base_value(self->settings[MYPAINT_BRUSH_SETTING_STROKE_THRESHOLD]) + 0.0001) {
// start new stroke
//printf("stroke start %f\n", pressure);
self->states[MYPAINT_BRUSH_STATE_STROKE_STARTED] = 1;
self->states[MYPAINT_BRUSH_STATE_STROKE] = 0.0;
}
} else {
if (pressure <= mypaint_mapping_get_base_value(self->settings[MYPAINT_BRUSH_SETTING_STROKE_THRESHOLD]) * 0.9 + 0.0001) {
// end stroke
//printf("stroke end\n");
self->states[MYPAINT_BRUSH_STATE_STROKE_STARTED] = 0;
}
}
}
// now follows input handling
float norm_dx, norm_dy, norm_dist, norm_speed;
norm_dx = step_dx / step_dtime / base_radius;
norm_dy = step_dy / step_dtime / base_radius;
norm_speed = hypotf(norm_dx, norm_dy);
norm_dist = norm_speed * step_dtime;
inputs[MYPAINT_BRUSH_INPUT_PRESSURE] = pressure * expf(mypaint_mapping_get_base_value(self->settings[MYPAINT_BRUSH_SETTING_PRESSURE_GAIN_LOG]));
inputs[MYPAINT_BRUSH_INPUT_SPEED1] = log(self->speed_mapping_gamma[0] + self->states[MYPAINT_BRUSH_STATE_NORM_SPEED1_SLOW])*self->speed_mapping_m[0] + self->speed_mapping_q[0];
inputs[MYPAINT_BRUSH_INPUT_SPEED2] = log(self->speed_mapping_gamma[1] + self->states[MYPAINT_BRUSH_STATE_NORM_SPEED2_SLOW])*self->speed_mapping_m[1] + self->speed_mapping_q[1];
inputs[MYPAINT_BRUSH_INPUT_RANDOM] = rng_double_next(self->rng);
inputs[MYPAINT_BRUSH_INPUT_STROKE] = MIN(self->states[MYPAINT_BRUSH_STATE_STROKE], 1.0);
inputs[MYPAINT_BRUSH_INPUT_DIRECTION] = fmodf (atan2f (self->states[MYPAINT_BRUSH_STATE_DIRECTION_DY], self->states[MYPAINT_BRUSH_STATE_DIRECTION_DX])/(2*M_PI)*360 + 180.0, 180.0);
inputs[MYPAINT_BRUSH_INPUT_TILT_DECLINATION] = self->states[MYPAINT_BRUSH_STATE_DECLINATION];
inputs[MYPAINT_BRUSH_INPUT_TILT_ASCENSION] = fmodf(self->states[MYPAINT_BRUSH_STATE_ASCENSION] + 180.0, 360.0) - 180.0;
inputs[MYPAINT_BRUSH_INPUT_CUSTOM] = self->states[MYPAINT_BRUSH_STATE_CUSTOM_INPUT];
if (self->print_inputs) {
printf("press=% 4.3f, speed1=% 4.4f\tspeed2=% 4.4f\tstroke=% 4.3f\tcustom=% 4.3f\n", (double)inputs[MYPAINT_BRUSH_INPUT_PRESSURE], (double)inputs[MYPAINT_BRUSH_INPUT_SPEED1], (double)inputs[MYPAINT_BRUSH_INPUT_SPEED2], (double)inputs[MYPAINT_BRUSH_INPUT_STROKE], (double)inputs[MYPAINT_BRUSH_INPUT_CUSTOM]);
}
// FIXME: this one fails!!!
//assert(inputs[MYPAINT_BRUSH_INPUT_SPEED1] >= 0.0 && inputs[MYPAINT_BRUSH_INPUT_SPEED1] < 1e8); // checking for inf
int i=0;
for (i=0; i<MYPAINT_BRUSH_SETTINGS_COUNT; i++) {
self->settings_value[i] = mypaint_mapping_calculate(self->settings[i], (inputs));
}
{
float fac = 1.0 - exp_decay (self->settings_value[MYPAINT_BRUSH_SETTING_SLOW_TRACKING_PER_DAB], step_ddab);
self->states[MYPAINT_BRUSH_STATE_ACTUAL_X] += (self->states[MYPAINT_BRUSH_STATE_X] - self->states[MYPAINT_BRUSH_STATE_ACTUAL_X]) * fac;
self->states[MYPAINT_BRUSH_STATE_ACTUAL_Y] += (self->states[MYPAINT_BRUSH_STATE_Y] - self->states[MYPAINT_BRUSH_STATE_ACTUAL_Y]) * fac;
}
{ // slow speed
float fac;
fac = 1.0 - exp_decay (self->settings_value[MYPAINT_BRUSH_SETTING_SPEED1_SLOWNESS], step_dtime);
self->states[MYPAINT_BRUSH_STATE_NORM_SPEED1_SLOW] += (norm_speed - self->states[MYPAINT_BRUSH_STATE_NORM_SPEED1_SLOW]) * fac;
fac = 1.0 - exp_decay (self->settings_value[MYPAINT_BRUSH_SETTING_SPEED2_SLOWNESS], step_dtime);
self->states[MYPAINT_BRUSH_STATE_NORM_SPEED2_SLOW] += (norm_speed - self->states[MYPAINT_BRUSH_STATE_NORM_SPEED2_SLOW]) * fac;
}
{ // slow speed, but as vector this time
// FIXME: offset_by_speed should be removed.
// Is it broken, non-smooth, system-dependent math?!
// A replacement could be a directed random offset.
float time_constant = expf(self->settings_value[MYPAINT_BRUSH_SETTING_OFFSET_BY_SPEED_SLOWNESS]*0.01)-1.0;
// Workaround for a bug that happens mainly on Windows, causing
// individual dabs to be placed far far away. Using the speed
// with zero filtering is just asking for trouble anyway.
if (time_constant < 0.002) time_constant = 0.002;
float fac = 1.0 - exp_decay (time_constant, step_dtime);
self->states[MYPAINT_BRUSH_STATE_NORM_DX_SLOW] += (norm_dx - self->states[MYPAINT_BRUSH_STATE_NORM_DX_SLOW]) * fac;
self->states[MYPAINT_BRUSH_STATE_NORM_DY_SLOW] += (norm_dy - self->states[MYPAINT_BRUSH_STATE_NORM_DY_SLOW]) * fac;
}
{ // orientation (similar lowpass filter as above, but use dabtime instead of wallclock time)
float dx = step_dx / base_radius;
float dy = step_dy / base_radius;
float step_in_dabtime = hypotf(dx, dy); // FIXME: are we recalculating something here that we already have?
float fac = 1.0 - exp_decay (exp(self->settings_value[MYPAINT_BRUSH_SETTING_DIRECTION_FILTER]*0.5)-1.0, step_in_dabtime);
float dx_old = self->states[MYPAINT_BRUSH_STATE_DIRECTION_DX];
float dy_old = self->states[MYPAINT_BRUSH_STATE_DIRECTION_DY];
// use the opposite speed vector if it is closer (we don't care about 180 degree turns)
if (SQR(dx_old-dx) + SQR(dy_old-dy) > SQR(dx_old-(-dx)) + SQR(dy_old-(-dy))) {
dx = -dx;
dy = -dy;
}
self->states[MYPAINT_BRUSH_STATE_DIRECTION_DX] += (dx - self->states[MYPAINT_BRUSH_STATE_DIRECTION_DX]) * fac;
self->states[MYPAINT_BRUSH_STATE_DIRECTION_DY] += (dy - self->states[MYPAINT_BRUSH_STATE_DIRECTION_DY]) * fac;
}
{ // custom input
float fac;
fac = 1.0 - exp_decay (self->settings_value[MYPAINT_BRUSH_SETTING_CUSTOM_INPUT_SLOWNESS], 0.1);
self->states[MYPAINT_BRUSH_STATE_CUSTOM_INPUT] += (self->settings_value[MYPAINT_BRUSH_SETTING_CUSTOM_INPUT] - self->states[MYPAINT_BRUSH_STATE_CUSTOM_INPUT]) * fac;
}
{ // stroke length
float frequency;
float wrap;
frequency = expf(-self->settings_value[MYPAINT_BRUSH_SETTING_STROKE_DURATION_LOGARITHMIC]);
self->states[MYPAINT_BRUSH_STATE_STROKE] += norm_dist * frequency;
// can happen, probably caused by rounding
if (self->states[MYPAINT_BRUSH_STATE_STROKE] < 0) self->states[MYPAINT_BRUSH_STATE_STROKE] = 0;
wrap = 1.0 + self->settings_value[MYPAINT_BRUSH_SETTING_STROKE_HOLDTIME];
if (self->states[MYPAINT_BRUSH_STATE_STROKE] > wrap) {
if (wrap > 9.9 + 1.0) {
// "inifinity", just hold stroke somewhere >= 1.0
self->states[MYPAINT_BRUSH_STATE_STROKE] = 1.0;
} else {
self->states[MYPAINT_BRUSH_STATE_STROKE] = fmodf(self->states[MYPAINT_BRUSH_STATE_STROKE], wrap);
// just in case
if (self->states[MYPAINT_BRUSH_STATE_STROKE] < 0) self->states[MYPAINT_BRUSH_STATE_STROKE] = 0;
}
}
}
// calculate final radius
float radius_log;
radius_log = self->settings_value[MYPAINT_BRUSH_SETTING_RADIUS_LOGARITHMIC];
self->states[MYPAINT_BRUSH_STATE_ACTUAL_RADIUS] = expf(radius_log);
if (self->states[MYPAINT_BRUSH_STATE_ACTUAL_RADIUS] < ACTUAL_RADIUS_MIN) self->states[MYPAINT_BRUSH_STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MIN;
if (self->states[MYPAINT_BRUSH_STATE_ACTUAL_RADIUS] > ACTUAL_RADIUS_MAX) self->states[MYPAINT_BRUSH_STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MAX;
// aspect ratio (needs to be caluclated here because it can affect the dab spacing)
self->states[MYPAINT_BRUSH_STATE_ACTUAL_ELLIPTICAL_DAB_RATIO] = self->settings_value[MYPAINT_BRUSH_SETTING_ELLIPTICAL_DAB_RATIO];
self->states[MYPAINT_BRUSH_STATE_ACTUAL_ELLIPTICAL_DAB_ANGLE] = self->settings_value[MYPAINT_BRUSH_SETTING_ELLIPTICAL_DAB_ANGLE];
}
