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implement brush sampling and spacing into the Stroke class

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This commit is contained in:
omigamedev
2017-03-27 00:20:04 +01:00
parent a385addae5
commit b9277f94e8
3 changed files with 76 additions and 39 deletions
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62
engine/brush.h
View File

@@ -23,20 +23,82 @@ public:
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;
}
};

51
engine/canvas.h
View File

@@ -41,8 +41,7 @@ public:
{
prng.seed(0);
m_strokes.emplace_back();
m_strokes.back().m_brush = brush;
m_strokes.back().add_point(point, pressure);
m_strokes.back().start(point, pressure, brush);
m_current_stroke = &m_strokes.back();
}
void stroke_update(glm::vec2 point, float pressure)
@@ -59,50 +58,26 @@ public:
glViewport(0, 0, m_width, m_height);
glEnable(GL_BLEND);
//auto mvp = glm::ortho(0.f, (float)m_width, (float)m_height, 0.f, -1.f, 1.f) *
// glm::translate(glm::vec3(point, 0)) *
// glm::scale(glm::vec3(30, 30, 1));
//auto& tex = TextureManager::get(m_current_stroke->m_brush.m_tex_id);
//tex.bind();
//m_sampler.bind(0);
//ui::ShaderManager::use(kShader::Stroke);
//ui::ShaderManager::u_int(kShaderUniform::Tex, 0);
//ui::ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
//ui::ShaderManager::u_float(kShaderUniform::Alpha, 1.f);
//ui::ShaderManager::u_vec4(kShaderUniform::Col, { 0, 0, 0, 1 });
//m_plane.draw_fill();
//m_sampler.unbind();
//tex.unbind();
auto proj = glm::ortho(0.f, (float)m_width, (float)m_height, 0.f, -1.f, 1.f);
auto m_brush = m_current_stroke->m_brush;
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
float angle = (m_brush.m_tip_angle + rnd_nor() * m_brush.m_jitter_angle) * (float)(M_PI * 2.0);
glm::vec2 pos = point + (rnd_vec() * m_brush.m_jitter_spread * 100.f);
float size = 100.f * m_brush.m_tip_size * (1.f - rnd_nor() * m_brush.m_jitter_scale);
float flow = m_brush.m_tip_flow * (1.f - rnd_nor() * m_brush.m_jitter_flow);
//alpha += glm::max(m_brush.m_tip_spacing * .2f, .01f);
auto mvp = proj *
//glm::translate(glm::vec3(i * 40 * m_tip_spacing, m_rtt.getHeight() / 2, 0)) *
glm::translate(glm::vec3(pos, 0)) *
glm::scale(glm::vec3(size, size, 1)) *
glm::eulerAngleZ(angle);
auto samples = m_current_stroke->compute_samples();
auto& tex = TextureManager::get(m_brush.m_tex_id);
tex.bind();
m_sampler.bind(0);
ShaderManager::use("stroke");
ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
ShaderManager::u_int(kShaderUniform::Tex, 0);
ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
ShaderManager::u_float(kShaderUniform::Alpha, flow);
m_plane.draw_fill();
for (const auto& s : samples)
{
auto mvp = proj *
glm::translate(glm::vec3(s.pos, 0)) *
glm::scale(glm::vec3(s.size, s.size, 1)) *
glm::eulerAngleZ(s.angle);
ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
ShaderManager::u_float(kShaderUniform::Alpha, s.flow);
m_plane.draw_fill();
}
m_sampler.unbind();
tex.unbind();

2
engine/layout.h
View File

@@ -1875,7 +1875,7 @@ public:
{
if (new_size.x > m_canvas->m_width)
{
m_canvas->create(new_size.x, new_size.y);
m_canvas->create((int)new_size.x, (int)new_size.y);
m_canvas->clear();
}
}