/* brushlib - The MyPaint Brush Library
* Copyright (C) 2007-2011 Martin Renold <martinxyz@gmx.ch>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <string.h>
#include <glib.h>
#include <math.h>
//#include "Python.h"
#include "brushsettings.hpp"
#include "mapping.hpp"
#define ACTUAL_RADIUS_MIN 0.2
#define ACTUAL_RADIUS_MAX 800 // safety guard against radius like 1e20 and against rendering overload with unexpected brush dynamics
/* The Brush class stores two things:
b) settings: constant during a stroke (eg. size, spacing, dynamics, color selected by the user)
a) states: modified during a stroke (eg. speed, smudge colors, time/distance to next dab, position filter states)
FIXME: Actually those are two orthogonal things. Should separate them:
a) brush settings class that is saved/loaded/selected (without states)
b) brush core class to draw the dabs (using an instance of the above)
In python, there are two kinds of instances from this: a "global
brush" which does the cursor tracking, and the "brushlist" where
the states are ignored. When a brush is selected, its settings are
copied into the global one, leaving the state intact.
*/
namespace brushlib {
class Brush {
public:
bool print_inputs; // debug menu
// for stroke splitting (undo/redo)
double stroke_total_painting_time;
double stroke_current_idling_time;
private:
// see also brushsettings.py
// the states (get_state, set_state, reset) that change during a stroke
float states[STATE_COUNT];
GRand * rng;
// Those mappings describe how to calculate the current value for each setting.
// Most of settings will be constant (eg. only their base_value is used).
Mapping * settings[BRUSH_SETTINGS_COUNT];
// the current value of all settings (calculated using the current state)
float settings_value[BRUSH_SETTINGS_COUNT];
// cached calculation results
float speed_mapping_gamma[2], speed_mapping_m[2], speed_mapping_q[2];
bool reset_requested;
public:
Brush() {
for (int i=0; i<BRUSH_SETTINGS_COUNT; i++) {
settings[i] = new Mapping(INPUT_COUNT);
}
rng = g_rand_new();
print_inputs = false;
for (int i=0; i<STATE_COUNT; i++) {
states[i] = 0;
}
new_stroke();
settings_base_values_have_changed();
reset_requested = true;
}
~Brush() {
for (int i=0; i<BRUSH_SETTINGS_COUNT; i++) {
delete settings[i];
}
g_rand_free (rng); rng = NULL;
}
void reset()
{
reset_requested = true;
}
void new_stroke()
{
stroke_current_idling_time = 0;
stroke_total_painting_time = 0;
}
void set_base_value (int id, float value) {
assert (id >= 0 && id < BRUSH_SETTINGS_COUNT);
settings[id]->base_value = value;
settings_base_values_have_changed ();
}
void set_mapping_n (int id, int input, int n) {
assert (id >= 0 && id < BRUSH_SETTINGS_COUNT);
settings[id]->set_n (input, n);
}
void set_mapping_point (int id, int input, int index, float x, float y) {
assert (id >= 0 && id < BRUSH_SETTINGS_COUNT);
settings[id]->set_point (input, index, x, y);
}
float get_state (int i)
{
assert (i >= 0 && i < STATE_COUNT);
return states[i];
}
void set_state (int i, float value)
{
assert (i >= 0 && i < STATE_COUNT);
states[i] = value;
}
private:
// returns the fraction still left after t seconds
float exp_decay (float T_const, float t)
{
// the argument might not make mathematical sense (whatever.)
if (T_const <= 0.001) {
return 0.0;
} else {
return exp(- t / T_const);
}
}
void settings_base_values_have_changed ()
{
// precalculate stuff that does not change dynamically
// Precalculate how the physical speed will be mapped to the speed input value.
// The formula for this mapping is:
//
// y = log(gamma+x)*m + q;
//
// x: the physical speed (pixels per basic dab radius)
// y: the speed input that will be reported
// gamma: parameter set by this user (small means a logarithmic mapping, big linear)
// m, q: parameters to scale and translate the curve
//
// The code below calculates m and q given gamma and two hardcoded constraints.
//
for (int i=0; i<2; i++) {
float gamma;
gamma = settings[(i==0)?BRUSH_SPEED1_GAMMA:BRUSH_SPEED2_GAMMA]->base_value;
gamma = exp(gamma);
float fix1_x, fix1_y, fix2_x, fix2_dy;
fix1_x = 45.0;
fix1_y = 0.5;
fix2_x = 45.0;
fix2_dy = 0.015;
float m, q;
float c1;
c1 = log(fix1_x+gamma);
m = fix2_dy * (fix2_x + gamma);
q = fix1_y - m*c1;
speed_mapping_gamma[i] = gamma;
speed_mapping_m[i] = m;
speed_mapping_q[i] = q;
}
}
// 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 (float step_dx, float step_dy, float step_dpressure, float step_declination, float step_ascension, float step_dtime)
{
float pressure;
float inputs[INPUT_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;
}
states[STATE_X] += step_dx;
states[STATE_Y] += step_dy;
states[STATE_PRESSURE] += step_dpressure;
states[STATE_DECLINATION] += step_declination;
states[STATE_ASCENSION] += step_ascension;
float base_radius = expf(settings[BRUSH_RADIUS_LOGARITHMIC]->base_value);
// FIXME: does happen (interpolation problem?)
states[STATE_PRESSURE] = CLAMP(states[STATE_PRESSURE], 0.0, 1.0);
pressure = states[STATE_PRESSURE];
{ // start / end stroke (for "stroke" input only)
if (!states[STATE_STROKE_STARTED]) {
if (pressure > settings[BRUSH_STROKE_THRESHOLD]->base_value + 0.0001) {
// start new stroke
//printf("stroke start %f\n", pressure);
states[STATE_STROKE_STARTED] = 1;
states[STATE_STROKE] = 0.0;
}
} else {
if (pressure <= settings[BRUSH_STROKE_THRESHOLD]->base_value * 0.9 + 0.0001) {
// end stroke
//printf("stroke end\n");
states[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 = sqrt(SQR(norm_dx) + SQR(norm_dy));
norm_dist = norm_speed * step_dtime;
inputs[INPUT_PRESSURE] = pressure;
inputs[INPUT_SPEED1] = log(speed_mapping_gamma[0] + states[STATE_NORM_SPEED1_SLOW])*speed_mapping_m[0] + speed_mapping_q[0];
inputs[INPUT_SPEED2] = log(speed_mapping_gamma[1] + states[STATE_NORM_SPEED2_SLOW])*speed_mapping_m[1] + speed_mapping_q[1];
inputs[INPUT_RANDOM] = g_rand_double (rng);
inputs[INPUT_STROKE] = MIN(states[STATE_STROKE], 1.0);
inputs[INPUT_DIRECTION] = fmodf (atan2f (states[STATE_DIRECTION_DY], states[STATE_DIRECTION_DX])/(2*M_PI)*360 + 180.0, 180.0);
inputs[INPUT_TILT_DECLINATION] = states[STATE_DECLINATION];
inputs[INPUT_TILT_ASCENSION] = states[STATE_ASCENSION];
inputs[INPUT_CUSTOM] = states[STATE_CUSTOM_INPUT];
if (print_inputs) {
g_print("press=% 4.3f, speed1=% 4.4f\tspeed2=% 4.4f\tstroke=% 4.3f\tcustom=% 4.3f\n", (double)inputs[INPUT_PRESSURE], (double)inputs[INPUT_SPEED1], (double)inputs[INPUT_SPEED2], (double)inputs[INPUT_STROKE], (double)inputs[INPUT_CUSTOM]);
}
// FIXME: this one fails!!!
//assert(inputs[INPUT_SPEED1] >= 0.0 && inputs[INPUT_SPEED1] < 1e8); // checking for inf
for (int i=0; i<BRUSH_SETTINGS_COUNT; i++) {
settings_value[i] = settings[i]->calculate (inputs);
}
{
float fac = 1.0 - exp_decay (settings_value[BRUSH_SLOW_TRACKING_PER_DAB], 1.0);
states[STATE_ACTUAL_X] += (states[STATE_X] - states[STATE_ACTUAL_X]) * fac; // FIXME: should this depend on base radius?
states[STATE_ACTUAL_Y] += (states[STATE_Y] - states[STATE_ACTUAL_Y]) * fac;
}
{ // slow speed
float fac;
fac = 1.0 - exp_decay (settings_value[BRUSH_SPEED1_SLOWNESS], step_dtime);
states[STATE_NORM_SPEED1_SLOW] += (norm_speed - states[STATE_NORM_SPEED1_SLOW]) * fac;
fac = 1.0 - exp_decay (settings_value[BRUSH_SPEED2_SLOWNESS], step_dtime);
states[STATE_NORM_SPEED2_SLOW] += (norm_speed - states[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 = exp(settings_value[BRUSH_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);
states[STATE_NORM_DX_SLOW] += (norm_dx - states[STATE_NORM_DX_SLOW]) * fac;
states[STATE_NORM_DY_SLOW] += (norm_dy - states[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(settings_value[BRUSH_DIRECTION_FILTER]*0.5)-1.0, step_in_dabtime);
float dx_old = states[STATE_DIRECTION_DX];
float dy_old = states[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;
}
states[STATE_DIRECTION_DX] += (dx - states[STATE_DIRECTION_DX]) * fac;
states[STATE_DIRECTION_DY] += (dy - states[STATE_DIRECTION_DY]) * fac;
}
{ // custom input
float fac;
fac = 1.0 - exp_decay (settings_value[BRUSH_CUSTOM_INPUT_SLOWNESS], 0.1);
states[STATE_CUSTOM_INPUT] += (settings_value[BRUSH_CUSTOM_INPUT] - states[STATE_CUSTOM_INPUT]) * fac;
}
{ // stroke length
float frequency;
float wrap;
frequency = expf(-settings_value[BRUSH_STROKE_DURATION_LOGARITHMIC]);
states[STATE_STROKE] += norm_dist * frequency;
// can happen, probably caused by rounding
if (states[STATE_STROKE] < 0) states[STATE_STROKE] = 0;
wrap = 1.0 + settings_value[BRUSH_STROKE_HOLDTIME];
if (states[STATE_STROKE] > wrap) {
if (wrap > 9.9 + 1.0) {
// "inifinity", just hold stroke somewhere >= 1.0
states[STATE_STROKE] = 1.0;
} else {
states[STATE_STROKE] = fmodf(states[STATE_STROKE], wrap);
// just in case
if (states[STATE_STROKE] < 0) states[STATE_STROKE] = 0;
}
}
}
// calculate final radius
float radius_log;
radius_log = settings_value[BRUSH_RADIUS_LOGARITHMIC];
states[STATE_ACTUAL_RADIUS] = expf(radius_log);
if (states[STATE_ACTUAL_RADIUS] < ACTUAL_RADIUS_MIN) states[STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MIN;
if (states[STATE_ACTUAL_RADIUS] > ACTUAL_RADIUS_MAX) states[STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MAX;
// aspect ratio (needs to be calculated here because it can affect the dab spacing)
states[STATE_ACTUAL_ELLIPTICAL_DAB_RATIO] = settings_value[BRUSH_ELLIPTICAL_DAB_RATIO];
states[STATE_ACTUAL_ELLIPTICAL_DAB_ANGLE] = settings_value[BRUSH_ELLIPTICAL_DAB_ANGLE];
}
// Called only from stroke_to(). Calculate everything needed to
// draw the dab, then let the surface do the actual drawing.
//
// This is only gets called right after update_states_and_setting_values().
// Returns true if the surface was modified.
bool prepare_and_draw_dab (Surface * surface)
{
float x, y, opaque;
float radius;
// ensure we don't get a positive result with two negative opaque values
if (settings_value[BRUSH_OPAQUE] < 0) settings_value[BRUSH_OPAQUE] = 0;
opaque = settings_value[BRUSH_OPAQUE] * settings_value[BRUSH_OPAQUE_MULTIPLY];
opaque = CLAMP(opaque, 0.0, 1.0);
//if (opaque == 0.0) return false; <-- cannot do that, since we need to update smudge state.
if (settings_value[BRUSH_OPAQUE_LINEARIZE]) {
// OPTIMIZE: no need to recalculate this for each dab
float alpha, beta, alpha_dab, beta_dab;
float dabs_per_pixel;
// dabs_per_pixel is just estimated roughly, I didn't think hard
// about the case when the radius changes during the stroke
dabs_per_pixel = (
settings[BRUSH_DABS_PER_ACTUAL_RADIUS]->base_value +
settings[BRUSH_DABS_PER_BASIC_RADIUS]->base_value
) * 2.0;
// the correction is probably not wanted if the dabs don't overlap
if (dabs_per_pixel < 1.0) dabs_per_pixel = 1.0;
// interpret the user-setting smoothly
dabs_per_pixel = 1.0 + settings[BRUSH_OPAQUE_LINEARIZE]->base_value*(dabs_per_pixel-1.0);
// see doc/brushdab_saturation.png
// beta = beta_dab^dabs_per_pixel
// <==> beta_dab = beta^(1/dabs_per_pixel)
alpha = opaque;
beta = 1.0-alpha;
beta_dab = powf(beta, 1.0/dabs_per_pixel);
alpha_dab = 1.0-beta_dab;
opaque = alpha_dab;
}
x = states[STATE_ACTUAL_X];
y = states[STATE_ACTUAL_Y];
float base_radius = expf(settings[BRUSH_RADIUS_LOGARITHMIC]->base_value);
if (settings_value[BRUSH_OFFSET_BY_SPEED]) {
x += states[STATE_NORM_DX_SLOW] * settings_value[BRUSH_OFFSET_BY_SPEED] * 0.1 * base_radius;
y += states[STATE_NORM_DY_SLOW] * settings_value[BRUSH_OFFSET_BY_SPEED] * 0.1 * base_radius;
}
if (settings_value[BRUSH_OFFSET_BY_RANDOM]) {
float amp = settings_value[BRUSH_OFFSET_BY_RANDOM];
if (amp < 0.0) amp = 0.0;
x += rand_gauss (rng) * amp * base_radius;
y += rand_gauss (rng) * amp * base_radius;
}
radius = states[STATE_ACTUAL_RADIUS];
if (settings_value[BRUSH_RADIUS_BY_RANDOM]) {
float radius_log, alpha_correction;
// go back to logarithmic radius to add the noise
radius_log = settings_value[BRUSH_RADIUS_LOGARITHMIC];
radius_log += rand_gauss (rng) * settings_value[BRUSH_RADIUS_BY_RANDOM];
radius = expf(radius_log);
radius = CLAMP(radius, ACTUAL_RADIUS_MIN, ACTUAL_RADIUS_MAX);
alpha_correction = states[STATE_ACTUAL_RADIUS] / radius;
alpha_correction = SQR(alpha_correction);
if (alpha_correction <= 1.0) {
opaque *= alpha_correction;
}
}
// color part
float color_h = settings[BRUSH_COLOR_H]->base_value;
float color_s = settings[BRUSH_COLOR_S]->base_value;
float color_v = settings[BRUSH_COLOR_V]->base_value;
float eraser_target_alpha = 1.0;
if (settings_value[BRUSH_SMUDGE] > 0.0) {
// mix (in RGB) the smudge color with the brush color
hsv_to_rgb_float (&color_h, &color_s, &color_v);
float fac = settings_value[BRUSH_SMUDGE];
if (fac > 1.0) fac = 1.0;
// If the smudge color somewhat transparent, then the resulting
// dab will do erasing towards that transparency level.
// see also ../doc/smudge_math.png
eraser_target_alpha = (1-fac)*1.0 + fac*states[STATE_SMUDGE_A];
// fix rounding errors (they really seem to happen in the previous line)
eraser_target_alpha = CLAMP(eraser_target_alpha, 0.0, 1.0);
if (eraser_target_alpha > 0) {
color_h = (fac*states[STATE_SMUDGE_RA] + (1-fac)*color_h) / eraser_target_alpha;
color_s = (fac*states[STATE_SMUDGE_GA] + (1-fac)*color_s) / eraser_target_alpha;
color_v = (fac*states[STATE_SMUDGE_BA] + (1-fac)*color_v) / eraser_target_alpha;
} else {
// we are only erasing; the color does not matter
color_h = 1.0;
color_s = 0.0;
color_v = 0.0;
}
rgb_to_hsv_float (&color_h, &color_s, &color_v);
}
if (settings_value[BRUSH_SMUDGE_LENGTH] < 1.0 and
// optimization, since normal brushes have smudge_length == 0.5 without actually smudging
(settings_value[BRUSH_SMUDGE] != 0.0 or not settings[BRUSH_SMUDGE]->is_constant())) {
float fac = settings_value[BRUSH_SMUDGE_LENGTH];
if (fac < 0.01) fac = 0.01;
int px, py;
px = ROUND(x);
py = ROUND(y);
// Calling get_color() is almost as expensive as rendering a
// dab. Because of this we use the previous value if it is not
// expected to hurt quality too much. We call it at most every
// second dab.
float r, g, b, a;
states[STATE_LAST_GETCOLOR_RECENTNESS] *= fac;
if (states[STATE_LAST_GETCOLOR_RECENTNESS] < 0.5*fac) {
states[STATE_LAST_GETCOLOR_RECENTNESS] = 1.0;
float smudge_radius = radius * expf(settings_value[BRUSH_SMUDGE_RADIUS_LOG]);
smudge_radius = CLAMP(smudge_radius, ACTUAL_RADIUS_MIN, ACTUAL_RADIUS_MAX);
surface->get_color (px, py, smudge_radius, &r, &g, &b, &a);
states[STATE_LAST_GETCOLOR_R] = r;
states[STATE_LAST_GETCOLOR_G] = g;
states[STATE_LAST_GETCOLOR_B] = b;
states[STATE_LAST_GETCOLOR_A] = a;
} else {
r = states[STATE_LAST_GETCOLOR_R];
g = states[STATE_LAST_GETCOLOR_G];
b = states[STATE_LAST_GETCOLOR_B];
a = states[STATE_LAST_GETCOLOR_A];
}
// updated the smudge color (stored with premultiplied alpha)
states[STATE_SMUDGE_A ] = fac*states[STATE_SMUDGE_A ] + (1-fac)*a;
// fix rounding errors
states[STATE_SMUDGE_A ] = CLAMP(states[STATE_SMUDGE_A], 0.0, 1.0);
states[STATE_SMUDGE_RA] = fac*states[STATE_SMUDGE_RA] + (1-fac)*r*a;
states[STATE_SMUDGE_GA] = fac*states[STATE_SMUDGE_GA] + (1-fac)*g*a;
states[STATE_SMUDGE_BA] = fac*states[STATE_SMUDGE_BA] + (1-fac)*b*a;
}
// eraser
if (settings_value[BRUSH_ERASER]) {
eraser_target_alpha *= (1.0-settings_value[BRUSH_ERASER]);
}
// HSV color change
color_h += settings_value[BRUSH_CHANGE_COLOR_H];
color_s += settings_value[BRUSH_CHANGE_COLOR_HSV_S];
color_v += settings_value[BRUSH_CHANGE_COLOR_V];
// HSL color change
if (settings_value[BRUSH_CHANGE_COLOR_L] || settings_value[BRUSH_CHANGE_COLOR_HSL_S]) {
// (calculating way too much here, can be optimized if necessary)
// this function will CLAMP the inputs
hsv_to_rgb_float (&color_h, &color_s, &color_v);
rgb_to_hsl_float (&color_h, &color_s, &color_v);
color_v += settings_value[BRUSH_CHANGE_COLOR_L];
color_s += settings_value[BRUSH_CHANGE_COLOR_HSL_S];
hsl_to_rgb_float (&color_h, &color_s, &color_v);
rgb_to_hsv_float (&color_h, &color_s, &color_v);
}
float hardness = CLAMP(settings_value[BRUSH_HARDNESS], 0.0, 1.0);
// anti-aliasing attempt (works surprisingly well for ink brushes)
float current_fadeout_in_pixels = radius * (1.0 - hardness);
float min_fadeout_in_pixels = settings_value[BRUSH_ANTI_ALIASING];
if (current_fadeout_in_pixels < min_fadeout_in_pixels) {
// need to soften the brush (decrease hardness), but keep optical radius
// so we tune both radius and hardness, to get the desired fadeout_in_pixels
float current_optical_radius = radius - (1.0-hardness)*radius/2.0;
// Equation 1: (new fadeout must be equal to min_fadeout)
// min_fadeout_in_pixels = radius_new*(1.0 - hardness_new)
// Equation 2: (optical radius must remain unchanged)
// current_optical_radius = radius_new - (1.0-hardness_new)*radius_new/2.0
//
// Solved Equation 1 for hardness_new, using Equation 2: (thanks to mathomatic)
float hardness_new = ((current_optical_radius - (min_fadeout_in_pixels/2.0))/(current_optical_radius + (min_fadeout_in_pixels/2.0)));
// Using Equation 1:
float radius_new = (min_fadeout_in_pixels/(1.0 - hardness_new));
hardness = hardness_new;
radius = radius_new;
}
// the functions below will CLAMP most inputs
hsv_to_rgb_float (&color_h, &color_s, &color_v);
return surface->draw_dab (x, y, radius, color_h, color_s, color_v, opaque, hardness, eraser_target_alpha,
states[STATE_ACTUAL_ELLIPTICAL_DAB_RATIO], states[STATE_ACTUAL_ELLIPTICAL_DAB_ANGLE],
settings_value[BRUSH_LOCK_ALPHA]);
}
// How many dabs will be drawn between the current and the next (x, y, pressure, +dt) position?
// WARNING: pressure is not used
float count_dabs_to (float x, float y, float /* pressure */, float dt)
{
float xx, yy;
float res1, res2, res3;
float dist;
if (states[STATE_ACTUAL_RADIUS] == 0.0) states[STATE_ACTUAL_RADIUS] = expf(settings[BRUSH_RADIUS_LOGARITHMIC]->base_value);
if (states[STATE_ACTUAL_RADIUS] < ACTUAL_RADIUS_MIN) states[STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MIN;
if (states[STATE_ACTUAL_RADIUS] > ACTUAL_RADIUS_MAX) states[STATE_ACTUAL_RADIUS] = ACTUAL_RADIUS_MAX;
// OPTIMIZE: expf() called too often
float base_radius = expf(settings[BRUSH_RADIUS_LOGARITHMIC]->base_value);
if (base_radius < ACTUAL_RADIUS_MIN) base_radius = ACTUAL_RADIUS_MIN;
if (base_radius > ACTUAL_RADIUS_MAX) base_radius = ACTUAL_RADIUS_MAX;
//if (base_radius < 0.5) base_radius = 0.5;
//if (base_radius > 500.0) base_radius = 500.0;
xx = x - states[STATE_X];
yy = y - states[STATE_Y];
//dp = pressure - pressure; // Not useful?
// TODO: control rate with pressure (dabs per pressure) (dpressure is useless)
if (states[STATE_ACTUAL_ELLIPTICAL_DAB_RATIO] > 1.0) {
// code duplication, see tiledsurface::draw_dab()
float angle_rad=states[STATE_ACTUAL_ELLIPTICAL_DAB_ANGLE]/360*2*M_PI;
float cs=cos(angle_rad);
float sn=sin(angle_rad);
float yyr=(yy*cs-xx*sn)*states[STATE_ACTUAL_ELLIPTICAL_DAB_RATIO];
float xxr=yy*sn+xx*cs;
dist = sqrt(yyr*yyr + xxr*xxr);
} else {
dist = hypotf(xx, yy);
}
// FIXME: no need for base_value or for the range checks above IF always the interpolation
// function will be called before this one
res1 = dist / states[STATE_ACTUAL_RADIUS] * settings[BRUSH_DABS_PER_ACTUAL_RADIUS]->base_value;
res2 = dist / base_radius * settings[BRUSH_DABS_PER_BASIC_RADIUS]->base_value;
res3 = dt * settings[BRUSH_DABS_PER_SECOND]->base_value;
return res1 + res2 + res3;
}
public:
// This function:
// - is called once for each motion event
// - does motion event interpolation
// - paints zero, one or several dabs
// - decides whether the stroke is finished (for undo/redo)
// returns true if the stroke is finished or empty
bool stroke_to (Surface * surface, float x, float y, float pressure, float xtilt, float ytilt, double dtime)
{
//printf("%f %f %f %f\n", (double)dtime, (double)x, (double)y, (double)pressure);
float tilt_ascension = 0.0;
float tilt_declination = 90.0;
if (xtilt != 0 || ytilt != 0) {
// shield us from insane tilt input
xtilt = CLAMP(xtilt, -1.0, 1.0);
ytilt = CLAMP(ytilt, -1.0, 1.0);
assert(std::isfinite(xtilt) && std::isfinite(ytilt));
tilt_ascension = 180.0*atan2(-xtilt, ytilt)/M_PI;
float e;
if (abs(xtilt) > abs(ytilt)) {
e = sqrt(1+ytilt*ytilt);
} else {
e = sqrt(1+xtilt*xtilt);
}
float rad = hypot(xtilt, ytilt);
float cos_alpha = rad/e;
if (cos_alpha >= 1.0) cos_alpha = 1.0; // fix numerical inaccuracy
tilt_declination = 180.0*acos(cos_alpha)/M_PI;
assert(std::isfinite(tilt_ascension));
assert(std::isfinite(tilt_declination));
}
// printf("xtilt %f, ytilt %f\n", (double)xtilt, (double)ytilt);
// printf("ascension %f, declination %f\n", (double)tilt_ascension, (double)tilt_declination);
pressure = CLAMP(pressure, 0.0, 1.0);
if (!std::isfinite(x) || !std::isfinite(y) ||
(x > 1e10 || y > 1e10 || x < -1e10 || y < -1e10)) {
// workaround attempt for https://gna.org/bugs/?14372
g_print("Warning: ignoring brush::stroke_to with insane inputs (x = %f, y = %f)\n", (double)x, (double)y);
x = 0.0;
y = 0.0;
pressure = 0.0;
}
// the assertion below is better than out-of-memory later at save time
assert(x < 1e8 && y < 1e8 && x > -1e8 && y > -1e8);
if (dtime < 0) g_print("Time jumped backwards by dtime=%f seconds!\n", dtime);
if (dtime <= 0) dtime = 0.0001; // protect against possible division by zero bugs
if (dtime > 0.100 && pressure && states[STATE_PRESSURE] == 0) {
// Workaround for tablets that don't report motion events without pressure.
// This is to avoid linear interpolation of the pressure between two events.
stroke_to (surface, x, y, 0.0, 90.0, 0.0, dtime-0.0001);
dtime = 0.0001;
}
g_rand_set_seed (rng, states[STATE_RNG_SEED]);
{ // calculate the actual "virtual" cursor position
// noise first
if (settings[BRUSH_TRACKING_NOISE]->base_value) {
// OPTIMIZE: expf() called too often
float base_radius = expf(settings[BRUSH_RADIUS_LOGARITHMIC]->base_value);
x += rand_gauss (rng) * settings[BRUSH_TRACKING_NOISE]->base_value * base_radius;
y += rand_gauss (rng) * settings[BRUSH_TRACKING_NOISE]->base_value * base_radius;
}
float fac = 1.0 - exp_decay (settings[BRUSH_SLOW_TRACKING]->base_value, 100.0*dtime);
x = states[STATE_X] + (x - states[STATE_X]) * fac;
y = states[STATE_Y] + (y - states[STATE_Y]) * fac;
}
// draw many (or zero) dabs to the next position
// see doc/stroke2dabs.png
float dist_moved = states[STATE_DIST];
float dist_todo = count_dabs_to (x, y, pressure, dtime);
//if (dtime > 5 || dist_todo > 300) {
if (dtime > 5 || reset_requested) {
reset_requested = false;
/*
TODO:
if (dist_todo > 300) {
// this happens quite often, eg when moving the cursor back into the window
// FIXME: bad to hardcode a distance threshold here - might look at zoomed image
// better detect leaving/entering the window and reset then.
g_print ("Warning: NOT drawing %f dabs.\n", dist_todo);
g_print ("dtime=%f, dx=%f\n", dtime, x-states[STATE_X]);
//must_reset = 1;
}
*/
//printf("Brush reset.\n");
for (int i=0; i<STATE_COUNT; i++) {
states[i] = 0;
}
states[STATE_X] = x;
states[STATE_Y] = y;
states[STATE_PRESSURE] = pressure;
// not resetting, because they will get overwritten below:
//dx, dy, dpress, dtime
states[STATE_ACTUAL_X] = states[STATE_X];
states[STATE_ACTUAL_Y] = states[STATE_Y];
states[STATE_STROKE] = 1.0; // start in a state as if the stroke was long finished
return true;
}
//g_print("dist = %f\n", states[STATE_DIST]);
enum { UNKNOWN, YES, NO } painted = UNKNOWN;
double dtime_left = dtime;
float step_dx, step_dy, step_dpressure, step_dtime;
float step_declination, step_ascension;
while (dist_moved + dist_todo >= 1.0) { // there are dabs pending
{ // linear interpolation (nonlinear variant was too slow, see SVN log)
float frac; // fraction of the remaining distance to move
if (dist_moved > 0) {
// "move" the brush exactly to the first dab (moving less than one dab)
frac = (1.0 - dist_moved) / dist_todo;
dist_moved = 0;
} else {
// "move" the brush from one dab to the next
frac = 1.0 / dist_todo;
}
step_dx = frac * (x - states[STATE_X]);
step_dy = frac * (y - states[STATE_Y]);
step_dpressure = frac * (pressure - states[STATE_PRESSURE]);
step_dtime = frac * (dtime_left - 0.0);
step_declination = frac * (tilt_declination - states[STATE_DECLINATION]);
step_ascension = frac * (tilt_ascension - states[STATE_ASCENSION]);
// Though it looks different, time is interpolated exactly like x/y/pressure.
}
update_states_and_setting_values (step_dx, step_dy, step_dpressure, step_declination, step_ascension, step_dtime);
bool painted_now = prepare_and_draw_dab (surface);
if (painted_now) {
painted = YES;
} else if (painted == UNKNOWN) {
painted = NO;
}
dtime_left -= step_dtime;
dist_todo = count_dabs_to (x, y, pressure, dtime_left);
}
{
// "move" the brush to the current time (no more dab will happen)
// Important to do this at least once every event, because
// brush_count_dabs_to depends on the radius and the radius can
// depend on something that changes much faster than only every
// dab (eg speed).
step_dx = x - states[STATE_X];
step_dy = y - states[STATE_Y];
step_dpressure = pressure - states[STATE_PRESSURE];
step_declination = tilt_declination - states[STATE_DECLINATION];
step_ascension = tilt_ascension - states[STATE_ASCENSION];
step_dtime = dtime_left;
//dtime_left = 0; but that value is not used any more
update_states_and_setting_values (step_dx, step_dy, step_dpressure, step_declination, step_ascension, step_dtime);
}
// save the fraction of a dab that is already done now
states[STATE_DIST] = dist_moved + dist_todo;
//g_print("dist_final = %f\n", states[STATE_DIST]);
// next seed for the RNG (GRand has no get_state() and states[] must always contain our full state)
states[STATE_RNG_SEED] = g_rand_int(rng);
// stroke separation logic (for undo/redo)
if (painted == UNKNOWN) {
if (stroke_current_idling_time > 0 || stroke_total_painting_time == 0) {
// still idling
painted = NO;
} else {
// probably still painting (we get more events than brushdabs)
painted = YES;
//if (pressure == 0) g_print ("info: assuming 'still painting' while there is no pressure\n");
}
}
if (painted == YES) {
//if (stroke_current_idling_time > 0) g_print ("idling ==> painting\n");
stroke_total_painting_time += dtime;
stroke_current_idling_time = 0;
// force a stroke split after some time
if (stroke_total_painting_time > 4 + 3*pressure) {
// but only if pressure is not being released
// FIXME: use some smoothed state for dpressure, not the output of the interpolation code
// (which might easily wrongly give dpressure == 0)
if (step_dpressure >= 0) {
return true;
}
}
} else if (painted == NO) {
//if (stroke_current_idling_time == 0) g_print ("painting ==> idling\n");
stroke_current_idling_time += dtime;
if (stroke_total_painting_time == 0) {
// not yet painted, start a new stroke if we have accumulated a lot of irrelevant motion events
if (stroke_current_idling_time > 1.0) {
return true;
}
} else {
// Usually we have pressure==0 here. But some brushes can paint
// nothing at full pressure (eg gappy lines, or a stroke that
// fades out). In either case this is the preferred moment to split.
if (stroke_total_painting_time+stroke_current_idling_time > 0.9 + 5*pressure) {
return true;
}
}
}
return false;
}
};
}