;
; iron_geometry.hsp — 2D/3D 幾何学計算
;
#ifndef __iron_geometry_hsp__
#define __iron_geometry_hsp__
#module iron_geometry

; Triangle area (2D, Heron's formula from vertices)
#defcfunc tri_area double x1, double y1, double x2, double y2, double x3, double y3
	return absf((x1*(y2-y3) + x2*(y3-y1) + x3*(y1-y2)) / 2.0)

; Distance point to line (2D)
#defcfunc point_line_dist double px, double py, double x1, double y1, double x2, double y2, local a, local b, local c
	a = y2 - y1 : b = x1 - x2 : c = x2*y1 - x1*y2
	return absf(a*px + b*py + c) / sqrt(a*a + b*b)

; Circle area / circumference
#defcfunc circle_area double r
	return 3.14159265358979 * r * r

#defcfunc circle_circumference double r
	return 2.0 * 3.14159265358979 * r

; Polygon area (Shoelace formula)
#defcfunc polygon_area array x, array y, int n, local area, local i, local j
	area = 0.0
	j = n - 1
	repeat n
		i = cnt
		area += (x(j) + x(i)) * (y(j) - y(i))
		j = i
	loop
	return absf(area / 2.0)

; 3D: Sphere volume / surface
#defcfunc sphere_volume double r
	return 4.0 / 3.0 * 3.14159265358979 * r * r * r

#defcfunc sphere_surface double r
	return 4.0 * 3.14159265358979 * r * r

#global
#endif