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126 lines
2.1 KiB
126 lines
2.1 KiB
/** @file snake1.c
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@author M.P. Hayes
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@date 5 Oct 2010
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@note The snake head deliberately moves off screen unless turned.
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*/
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#include "system.h"
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#include "navswitch.h"
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#include "tinygl.h"
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#include "pacer.h"
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/* Define polling rate in Hz. */
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#define LOOP_RATE 300
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#define SNAKE_SPEED 2
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enum dir {DIR_N, DIR_E, DIR_S, DIR_W};
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typedef enum dir dir_t;
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struct snake
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{
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/* Current head of snake. */
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tinygl_point_t pos;
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/* Current direction. */
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enum dir dir;
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};
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typedef struct snake snake_t;
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static snake_t snake_move (snake_t snake)
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{
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switch (snake.dir)
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{
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case DIR_N:
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snake.pos.y = snake.pos.y - 1;
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break;
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case DIR_E:
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snake.pos.x = snake.pos.x + 1;
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break;
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case DIR_S:
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snake.pos.y = snake.pos.y + 1;
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break;
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case DIR_W:
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snake.pos.x = snake.pos.x - 1;
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break;
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}
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tinygl_draw_point (snake.pos, 1);
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return snake;
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}
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static snake_t snake_turn_left (snake_t snake)
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{
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dir_t newdir[] = {DIR_W, DIR_N, DIR_E, DIR_S};
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snake.dir = newdir[snake.dir];
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return snake;
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}
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static snake_t snake_turn_right (snake_t snake)
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{
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dir_t newdir[] = {DIR_E, DIR_S, DIR_W, DIR_N};
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snake.dir = newdir[snake.dir];
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return snake;
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}
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int main (void)
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{
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snake_t snake;
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int tick = 0;
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system_init ();
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snake.dir = DIR_N;
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snake.pos.x = TINYGL_WIDTH / 2;
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snake.pos.y = TINYGL_HEIGHT - 1;
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tinygl_init (LOOP_RATE);
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navswitch_init ();
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pacer_init (LOOP_RATE);
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tinygl_draw_point (snake.pos, 1);
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/* Paced loop. */
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while (1)
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{
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/* Wait for next tick. */
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pacer_wait ();
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navswitch_update ();
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tick = tick + 1;
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if (tick > LOOP_RATE / SNAKE_SPEED)
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{
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tick = 0;
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snake = snake_move (snake);
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}
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if (navswitch_push_event_p (NAVSWITCH_WEST))
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{
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snake = snake_turn_left (snake);
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}
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if (navswitch_push_event_p (NAVSWITCH_EAST))
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{
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snake = snake_turn_right (snake);
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}
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tinygl_update ();
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}
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return 0;
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}
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