std::pair< T, T > intersection( const ray<T,2u>& ray, const circle<T>& circle )
{
// check for no intersection
const T a = dot( ray.direction(), ray.direction() );
const T b = T(2.) * sum( ray.direction() * ( ray.source() - circle.center() ) );
const T c = dot( circle.center(), circle.center() )
+ dot( ray.source(), ray.source() )
- T(2.) * dot( ray.source(), circle.center() )
- sqr( circle.radius() );
return solve_quadratic_equation(a,b,c);
}
void draw_indicator(canvas& cnv, circle cp, float val, color c)
{
constexpr float w_factor = 0.05; // relative width of the indicator
constexpr float h_factor = 0.2; // relative height of the indicator
using namespace radial_consts;
auto state = cnv.new_state();
auto center = cp.center();
cnv.translate({ center.x, center.y });
cnv.rotate(offset + (val * range));
float r = cp.radius * 0.85;
float ind_w = r * w_factor;
float ind_h = r * h_factor;
rect ind_r = { -ind_w, -ind_h, ind_w, ind_h };
ind_r = ind_r.move(0, r*0.6);
draw_indicator(cnv, ind_r, c);
}
void draw_radial_marks(canvas& cnv, circle cp, float size, color c)
{
using namespace radial_consts;
auto state = cnv.new_state();
auto center = cp.center();
constexpr auto num_divs = 50;
float div = range / num_divs;
auto const& theme = get_theme();
cnv.translate({ center.x, center.y });
cnv.stroke_style(theme.ticks_color);
for (int i = 0; i != num_divs+1; ++i)
{
float from = cp.radius;
if (i % (num_divs / 10))
{
// Minor ticks
from -= size / 4;
cnv.line_width(theme.minor_ticks_width);
cnv.stroke_style(c.level(theme.minor_ticks_level));
}
else
{
// Major ticks
cnv.line_width(theme.major_ticks_width);
cnv.stroke_style(c.level(theme.major_ticks_level));
}
float angle = offset + (M_PI / 2) + (i * div);
float sin_ = std::sin(angle);
float cos_ = std::cos(angle);
float to = cp.radius - (size / 2);
cnv.move_to({ from * cos_, from * sin_ });
cnv.line_to({ to * cos_, to * sin_ });
cnv.stroke();
}
}
void draw_radial_labels(
canvas& cnv
, circle cp
, float size
, float font_size
, std::string const labels[]
, std::size_t num_labels
)
{
if (num_labels < 2)
return; // Nothing to do
using namespace radial_consts;
auto state = cnv.new_state();
auto center = cp.center();
float div = range / (num_labels-1);
auto const& theme = get_theme();
cnv.translate({ center.x, center.y });
cnv.text_align(cnv.middle | cnv.center);
cnv.fill_style(theme.label_font_color);
cnv.font(
theme.label_font,
theme.label_font_size * font_size,
theme.label_style
);
for (int i = 0; i != num_labels; ++i)
{
float angle = offset + (M_PI / 2) + (i * div);
float sin_ = std::sin(angle);
float cos_ = std::cos(angle);
cnv.fill_text({ cp.radius * cos_, cp.radius * sin_ }, labels[i].c_str());
}
}
