field.c

#include <math.h>
#include <stdbool.h>
#include <stdlib.h>

#include "physics.h"


// Compute E*qP/norm(qP)
// Return false if norm(qP) < eps
/// qP = vectoriel(P-q)
/// Compute the vector value of the field generated by a charge at a given point in space.
bool compute_e(charge_t c, vec2 p, double eps, vec2 *e) {
	vec2 relative_position = vec2_sub(p, c.pos);
	if (vec2_norm(relative_position) < eps) return false;
	double field = K * c.q / vec2_norm_sqr(relative_position);
	*e = vec2_mul(field, vec2_normalize(relative_position));
	return true;
}

// Compute the normalized sum of Ei*qiP/norm(qiP)
// Return false if for some qiP, norm(qiP) < eps
bool compute_total_normalized_e(charge_t *charges, int num_charges, vec2 p, double eps, vec2 *e) {
	*e = vec2_create_zero();
	vec2 ei = vec2_create_zero();
	for (size_t i = 0; i < num_charges; ++i) {
		if (!compute_e(charges[i], p, eps, &ei)) return false;
		*e = vec2_add(acc, ei);
	}
	*e = vec2_normalize(*e);
	return true;
}

// Compute and then draw all the points belonging to a field line,
// starting from pos0.
// Returns false if pos0 is not a valid position
// (for example if pos0 is too close to a charge).
static bool draw_field_line(struct gfx_context_t *ctxt, charge_t *charges, int num_charges, double dx, vec2 pos0, double x0, double x1, double y0, double y1) {
	return EXIT_SUCCESS;
}

// Draw all the charges
// A circle with minus sign for negative charges
// A circle with a plus sign for positive charges
static void draw_charges(struct gfx_context_t *context, charge_t *charges, int num_charges, double x0, double x1, double y0, double y1) {
}