njin_spline.h

#pragma once
#include "_math.h"
#include "_types.h"
#include <vector>
 
namespace njin {
struct context;


enum spline_kind {
  spline_catmull_rom,
  spline_bezier,
};

struct spline3d {
  std::vector<vec3> points;              
  spline_kind kind = spline_catmull_rom; 
  bool closed = false;                   
  f32 alpha = 0.5f;
  std::vector<f32> table; 
  i32 steps = 0;          
};

struct spline2d {
  std::vector<vec2> points;              
  spline_kind kind = spline_catmull_rom; 
  bool closed = false;                   
  f32 alpha = 0.5f;                      
  std::vector<f32> table; 
  i32 steps = 0;          
};

void spline_bake(spline3d &spline, i32 steps = 64);
void spline_bake(spline2d &spline, i32 steps = 64);

i32 spline_segment_count(const spline3d &spline);
i32 spline_segment_count(const spline2d &spline);

vec3 spline_point(const spline3d &spline, f32 t);
vec2 spline_point(const spline2d &spline, f32 t);

vec3 spline_tangent(const spline3d &spline, f32 t);
vec2 spline_tangent(const spline2d &spline, f32 t);

f32 spline_length(const spline3d &spline);
f32 spline_length(const spline2d &spline);

f32 spline_t_at(const spline3d &spline, f32 distance);
f32 spline_t_at(const spline2d &spline, f32 distance);

vec3 spline_point_at(const spline3d &spline, f32 distance);
vec2 spline_point_at(const spline2d &spline, f32 distance);

vec3 spline_tangent_at(const spline3d &spline, f32 distance);
vec2 spline_tangent_at(const spline2d &spline, f32 distance);

f32 spline_nearest(const spline3d &spline, vec3 p, vec3 *out_point = nullptr);
f32 spline_nearest(const spline2d &spline, vec2 p, vec2 *out_point = nullptr);

enum spline_end {
  spline_stop,      
  spline_loop,      
  spline_ping_pong, 
};

struct spline_follower {
  f32 distance = 0.0f;        
  f32 speed = 1.0f;           
  spline_end end = spline_stop; 
  bool finished = false;      
};

vec3 spline_follow(const spline3d &spline, spline_follower &follower, f32 dt);
vec2 spline_follow(const spline2d &spline, spline_follower &follower, f32 dt);

void spline_draw_debug(context &ctx, const spline3d &spline, rgba color = {1.0f, 0.8f, 0.2f, 1.0f});
void spline_draw_debug(context &ctx, const spline2d &spline, rgba color = {1.0f, 0.8f, 0.2f, 1.0f});
} // namespace njin