Files
panopainter/engine/brush.h

121 lines
3.7 KiB
C++

#pragma once
#include "rtt.h"
NS_START
class Brush
{
public:
int id;
std::string m_name;
uint16_t m_tex_id;
glm::vec4 m_tip_color;
float m_tip_size;
float m_tip_spacing;
float m_tip_flow;
float m_tip_angle;
float m_jitter_scale;
float m_jitter_angle;
float m_jitter_spread;
float m_jitter_flow;
};
class Stroke
{
public:
struct Sample
{
glm::vec2 pos;
float size;
float flow;
float angle;
};
struct Keypoint
{
glm::vec2 pos;
float pressure;
float dist;
};
int m_layer;
float m_dist;
float m_step;
ui::Brush m_brush;
std::vector<Keypoint> m_keypoints;
std::vector<Sample> m_samples;
int m_last_kp;
std::minstd_rand prng;
void start(glm::vec2 pos, float pressure, const ui::Brush& brush)
{
m_last_kp = 0;
m_dist = 0.f;
m_step = glm::max(brush.m_tip_spacing * brush.m_tip_size * 30, 0.1f);
m_brush = brush;
add_point(pos, pressure);
}
void add_point(glm::vec2 pos, float pressure)
{
float dist = m_keypoints.empty() ? 0.f :
m_keypoints.back().dist + glm::distance(m_keypoints.back().pos, pos);
m_keypoints.emplace_back();
m_keypoints.back().pos = pos;
m_keypoints.back().pressure = pressure;
m_keypoints.back().dist = dist;
}
bool has_sample()
{
return m_keypoints.empty() ? false : // no keypoints
(m_keypoints.back().dist > (m_dist + m_step)); // check if next kp is closer than spacing
}
std::vector<Sample> compute_samples()
{
int nsamples = (int)glm::floor((m_keypoints.back().dist - m_dist) / m_step);
std::vector<Sample> samples;
samples.reserve(nsamples); // preallocate the estimate number of samples
while (m_keypoints.back().dist > (m_dist + m_step))
{
m_dist += m_step;
while (m_dist > m_keypoints[m_last_kp + 1].dist)
m_last_kp++;
const auto& A = m_keypoints[m_last_kp];
const auto& B = m_keypoints[m_last_kp + 1]; // NOTE: this should be true when while is true
float t = (m_dist - A.dist) / (B.dist - A.dist); // NOTE: must be A != B
auto pos = glm::lerp(A.pos, B.pos, t);
float pressure = glm::lerp(A.pressure, B.pressure, t);
auto s = randomize_sample(pos, pressure);
samples.push_back(s);
}
return std::move(samples);
}
Sample randomize_sample(const glm::vec2& pos, float pressure)
{
auto rnd_nor = [&] { return float((double)prng() / (double)prng.max()); }; // normalized [0, +1]
auto rnd_neg = [&] { return float((double)prng() / (double)prng.max() * 2.0 - 1.0); }; // normalized [-1, +1]
auto rnd_rad = [&] { return float((double)prng() / (double)prng.max() * M_PI * 2.0); }; // normalized [0, 2pi]
auto rnd_vec = [&] { float rad = rnd_rad(); return glm::vec2(cosf(rad), sinf(rad)); }; // normalized direction vector
Sample s;
s.angle = (m_brush.m_tip_angle + rnd_nor() * m_brush.m_jitter_angle) * (float)(M_PI * 2.0);
s.pos = pos + (rnd_vec() * m_brush.m_jitter_spread * 100.f);
s.size = 100.f * m_brush.m_tip_size * (1.f - rnd_nor() * m_brush.m_jitter_scale);
s.flow = m_brush.m_tip_flow * (1.f - rnd_nor() * m_brush.m_jitter_flow);
return s;
}
};
class Layer
{
public:
RTT m_rtt;
bool m_visible = true;
bool m_locked = false;
float m_alpha = 1.f;
std::string m_name;
bool create(int width, int height, std::string name)
{
m_rtt.create(width, height);
return true;
}
};
NS_END