#include <stdarg.h>
#include "lighting.h"

static void process_vwedge_vis_helper(VLine* vline, va_list ap);

/* Returns a new vwedge */
VWedge* create_vwedge()
{
	VWedge* wedge = malloc(sizeof(VWedge));
	create_heap(&wedge->vis, 5, 5, create_vline, destroy_vline);
	return wedge;
}

/* Frees a vwedge */
void destroy_vwedge(VWedge* wedge)
{
	destroy_heap(&wedge->vis);
	free(wedge);
}

/* Fill out the vis field of wedge */
void process_vwedge_vis(VWedge* wedge)
{
	/* Cast rays at regular intervals */
	/* Cast a ray toward every world vertex */
	process_heap_va(&wedge->vis, PROC_VA(process_vwedge_vis_helper), wedge);
}

/* Renders the vwedge to bmp */
void draw_vwedge(BITMAP* bmp, VWedge* wedge, int color)
{
	draw_vlines(bmp, wedge->x, wedge->y, &wedge->vis, color);
}

/* The most important function! */
static void process_vwedge_vis_helper(VLine* l, va_list ap)
{
	VWedge* w = va_arg(ap, VWedge*);
	VLine* l2;
	VLine** lines = (VLine**)w->vis.data;
	int x, y, r, i, x2, y2, r2, i2;
	
	if (same_side(w->x, w->y, l->x1, l->y1, l->prev->x1, l->prev->y1, l->x2,
			l->y2))
		l->skip = l->prev->skip = 1;

	/* Cast a ray toward each vertex and find which line intercepts it */
	x = l->x1;
	y = l->y1;
	r = -1;
	for (i2 = 0; i2 < w->vis.count; i2++) {
		l2 = lines[i2];
		if (l2->skip) continue;
		if (intersection(w->x, w->y, l->x1, l->y1, l2->x1, l2->y1,
				l2->x2, l2->y2, &x2, &y2, !l->skip)) {
			r2 = sqr_dist(w->x, w->y, x2, y2);
			if (r == -1 || r >= r2) {
				r = r2;
				x = x2;
				y = y2;
				i = i2;
			}
		}
	}
	if (l->skip) {
		l->skip = l->prev->skip = 0;
		if (r == -1 || r >= sqr_dist(w->x, w->y, l->x1, l->y1))
			add_vertex_to_vline(l, l->x1, l->y1);
	}
	if (r > -1) add_vertex_to_vline(lines[i], x, y);
}