mystnb/src/engine.c

#include <gint/display.h>
#include <gint/keyboard.h>
#include "engine.h"

#define CELL_X(x) (-2 + 10 * (x))
#define CELL_Y(y) (-3 + 10 * (y))

//---
//  Animations
//---

void engine_tick(struct game *game, int dt)
{
	game->time += dt;

	/* Update the animations for every player */
	for(int p = 0; game->players[p]; p++)
	{
		struct player *player = game->players[p];

		player->anim.duration -= dt;
		if(player->anim.duration > 0) continue;

		/* Call the animation function to generate the next frame */
		player->idle = !player->anim.function(&player->anim, 0);
	}
}

//---
//  Rendering
//---

static void engine_draw_player(struct player const *player)
{
	dframe(CELL_X(player->x) - 1 + player->anim.dx,
	       CELL_Y(player->y) - 5 + player->anim.dy,
	       player->anim.img);
}

void engine_draw(struct game const *game)
{
	dclear(C_WHITE);
	dimage(0, 0, game->map->img);

	for(int p = 0; game->players[p]; p++)
	{
		engine_draw_player(game->players[p]);
	}
}

//---
//  Physics
//---

/* Check whether a cell of the map is walkable */
static int map_walkable(struct map const *map, int x, int y)
{
	int tile = map->tiles[y * map->w + x];
	return (tile != TILE_WALL);
}

int engine_move(struct game *game, struct player *player, int dir)
{
	int dx = (dir == DIR_RIGHT) - (dir == DIR_LEFT);
	int dy = (dir == DIR_DOWN)  - (dir == DIR_UP);
	int olddir = player->dir;

	/* Don't move players that are already moving */
	if(!player->idle) return 0;

	/* Update the direction */
	player->dir = dir;
	player->anim.dir = dir;

	/* Only move the player if the destination is walkable */
	if(!map_walkable(game->map, player->x + dx, player->y + dy))
	{
		/* If not, set the new idle animation */
		if(dir != olddir)
		{
			player->idle = !anim_player_idle(&player->anim,1);
		}
		return 0;
	}

	player->x += dx;
	player->y += dy;

	/* Set the walking animation */
	player->idle = !anim_player_walking(&player->anim, 1);

	return 1;
}