443 lines
11 KiB
C
443 lines
11 KiB
C
#include <assert.h>
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#include <stdint.h>
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#include "../../config.h"
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#include "../../compat/pgmspace.h"
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#include "../../pixel.h"
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#include "../../random/prng.h"
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#include "../../util.h"
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#include "../../joystick/joystick.h"
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#include "../../menu/menu.h"
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#include "snake_game.h"
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#if defined MENU_SUPPORT && defined GAME_SNAKE
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// snake icon (MSB is leftmost pixel)
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static const uint8_t icon[8] PROGMEM =
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{0xff, 0x81, 0xbd, 0xa5, 0xa5, 0xad, 0xa1, 0xbf};
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game_descriptor_t snake_game_descriptor __attribute__((section(".game_descriptors"))) =
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{
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&snake_game,
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icon,
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};
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#endif
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// If defined, joystick controls are NOT as "seen" by the snake but absolute,
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// that is, if pressing up, snake goes up, etc.
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#define SNAKE_NEWCONTROL
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// limits
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#ifndef USNAKE_MAX_LENGTH
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#define USNAKE_MAX_LENGTH 64u
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#endif
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#ifndef SNAKE_MAX_APPLES
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#define SNAKE_MAX_APPLES 10
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#endif
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// delays (in milliseconds)
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#ifndef SNAKE_CYCLE_DELAY
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#define SNAKE_CYCLE_DELAY 100
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#endif
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#ifndef SNAKE_TERMINATION_DELAY
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#define SNAKE_TERMINATION_DELAY 60
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#endif
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// colors
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#define SNAKE_COLOR_BORDER 3
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#define SNAKE_COLOR_PROTAGONIST 3
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#define SNAKE_COLOR_APPLE 3
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/**
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* Directions of the snake.
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*/
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enum snake_dir
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{
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SNAKE_DIR_UP, //!< SNAKE_DIR_UP Snake is heading up.
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SNAKE_DIR_RIGHT,//!< SNAKE_DIR_RIGHT Snake is heading right.
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SNAKE_DIR_DOWN, //!< SNAKE_DIR_DOWN Snake is heading down.
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SNAKE_DIR_LEFT, //!< SNAKE_DIR_LEFT Snake is heading left.
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SNAKE_DIR_NONE //!< SNAKE_DIR_NONE Helper value for a "resting" joystick.
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};
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#ifdef NDEBUG
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typedef uint8_t snake_dir_t;
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#else
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typedef enum snake_dir snake_dir_t;
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#endif
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/**
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* This structure represents the snake character itself. It keeps track of the
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* snake's segments, its head and tail and the direction it is heading.
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*/
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typedef struct snake_protagonist
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{
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pixel aSegments[USNAKE_MAX_LENGTH]; /**< All segments of the snake. */
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uint8_t nHeadIndex; /**< Index of the head segment. */
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uint8_t nTailIndex; /**< Index of the tail segment. */
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snake_dir_t dir; /**< Direction of the snake. */
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} snake_protagonist_t;
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/**
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* This structure keeps track of all apples which are on the playing field.
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*/
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typedef struct snake_apples
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{
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pixel aApples[SNAKE_MAX_APPLES]; /**< All apple positions */
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uint8_t nAppleCount; /**< Counter of currently existing apples*/
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} snake_apples_t;
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/**
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* Moves a pixel to the given direction.
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* @param pxNext pixel to be moved
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* @param dir direction
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*/
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static pixel snake_applyDirection(pixel pxNext,
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snake_dir_t dir)
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{
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assert(dir < 4);
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static int8_t const nDelta[] = {0, -1, 0, 1, 0};
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return (pixel){pxNext.x + nDelta[dir], pxNext.y + nDelta[dir + 1]};
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}
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/**
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* This functions draws a border around the playing field.
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*/
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static void snake_drawBorder(void)
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{
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#if NUM_COLS == NUM_ROWS
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for (uint8_t i = NUM_COLS; i--;)
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{
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setpixel((pixel){i, 0}, SNAKE_COLOR_BORDER);
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setpixel((pixel){i, NUM_ROWS - 1}, SNAKE_COLOR_BORDER);
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setpixel((pixel){0, i}, SNAKE_COLOR_BORDER);
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setpixel((pixel){NUM_COLS -1, i}, SNAKE_COLOR_BORDER);
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}
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#else
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for (uint8_t x = NUM_COLS; x--;)
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{
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setpixel((pixel){x, 0}, SNAKE_COLOR_BORDER);
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setpixel((pixel){x, NUM_ROWS - 1}, SNAKE_COLOR_BORDER);
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}
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for (uint8_t y = NUM_ROWS; y--;)
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{
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setpixel((pixel){0, y}, SNAKE_COLOR_BORDER);
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setpixel((pixel){NUM_COLS - 1, y}, SNAKE_COLOR_BORDER);
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}
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#endif
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}
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#ifdef GAME_SNAKE
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/**
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* Translates port information into directions.
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* @return Current direction of the joystick
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*/
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static snake_dir_t snake_queryJoystick(void)
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{
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snake_dir_t dirJoystick;
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if (JOYISUP)
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{
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dirJoystick = SNAKE_DIR_UP;
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}
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else if (JOYISRIGHT)
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{
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dirJoystick = SNAKE_DIR_RIGHT;
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}
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else if (JOYISDOWN)
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{
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dirJoystick = SNAKE_DIR_DOWN;
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}
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else if (JOYISLEFT)
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{
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dirJoystick = SNAKE_DIR_LEFT;
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}
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else
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{
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dirJoystick = SNAKE_DIR_NONE;
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}
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return dirJoystick;
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}
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#endif
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/**
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* Initializes the structure which represents the snake itself.
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* @param pprotSnake The protagonist structure to be initialized.
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*/
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static void snake_initGameProtagonist(snake_protagonist_t *pprotSnake)
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{
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pprotSnake->aSegments[0] = (pixel){NUM_COLS / 2, NUM_ROWS / 2};
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pprotSnake->aSegments[1] = (pixel){NUM_COLS / 2, NUM_ROWS / 2 - 1};
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pprotSnake->nTailIndex = 0;
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pprotSnake->nHeadIndex = 1;
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pprotSnake->dir = SNAKE_DIR_UP;
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}
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#ifdef GAME_SNAKE
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/**
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* Determines the next direction of the snake depending on joystick input.
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* @param pprotSnake Protagonist structure to be controlled.
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* @param pdirLast The last joystick movement to avoid key repeat.
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*/
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static void snake_userControl(snake_protagonist_t *pprotSnake,
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snake_dir_t *pdirLast)
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{
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snake_dir_t dirJoystick = snake_queryJoystick();
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#ifdef SNAKE_NEWCONTROL
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if (dirJoystick != SNAKE_DIR_NONE)
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{
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// valid transitions can only be uneven
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if ((pprotSnake->dir + dirJoystick) & 0x01)
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{
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pprotSnake->dir = dirJoystick;
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}
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}
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#else
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if ((dirJoystick ^ *pdirLast) && (dirJoystick != SNAKE_DIR_NONE))
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{ // only left or right movements are valid
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if (dirJoystick & 0x01)
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{
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// rotate through directions (either clockwise or counterclockwise)
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pprotSnake->dir = (pprotSnake->dir +
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(dirJoystick == SNAKE_DIR_LEFT ? 3 : 1)) % 4u;
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}
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}
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*pdirLast = dirJoystick;
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#endif
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}
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#endif
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#ifdef ANIMATION_SNAKE
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/**
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* Approaches directions which may lead to an apple.
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* @param pprotSnake The hungry protagonist.
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* @param pApples A bunch of apples.
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*/
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static void snake_autoRoute(snake_protagonist_t *pprotSnake,
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snake_apples_t *pApples)
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{
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pixel pxHead = pprotSnake->aSegments[pprotSnake->nHeadIndex];
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if (random8() < 80)
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{
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uint8_t nNextApple = 0;
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if (pApples->nAppleCount)
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{
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uint8_t nMinDist = UINT8_MAX;
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for (uint8_t i = 0; i < pApples->nAppleCount; ++i)
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{
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uint8_t nDistX;
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if (pxHead.x > pApples->aApples[i].x)
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{
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nDistX = pxHead.x - pApples->aApples[i].x;
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}
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else
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{
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nDistX = pApples->aApples[i].x - pxHead.x;
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}
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uint8_t nDistY;
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if (pxHead.y > pApples->aApples[i].y)
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{
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nDistY = pxHead.y - pApples->aApples[i].y;
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}
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else
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{
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nDistY = pApples->aApples[i].y - pxHead.y;
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}
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if ((nDistX + nDistY) < nMinDist)
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{
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nMinDist = nDistX + nDistY;
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nNextApple = i;
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}
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}
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if (pprotSnake->dir ^ 0x01) // vertical direction?
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{
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pprotSnake->dir = pApples->aApples[nNextApple].x > pxHead.x ?
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SNAKE_DIR_LEFT : SNAKE_DIR_RIGHT;
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}
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else
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{
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pprotSnake->dir = pApples->aApples[nNextApple].y > pxHead.y ?
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SNAKE_DIR_DOWN : SNAKE_DIR_UP;
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}
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}
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}
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for (uint8_t i = 4; i--;)
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{
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pixel pxTest = snake_applyDirection(pxHead, pprotSnake->dir);
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if (get_pixel(pxTest))
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{
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for (uint8_t j = pApples->nAppleCount; j--;)
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{
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if ((pxTest.x == pApples->aApples[j].x) &&
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(pxTest.y == pApples->aApples[j].y))
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{
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return;
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}
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}
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pprotSnake->dir = (pprotSnake->dir + 1) % 4u;
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}
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else
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{
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break;
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}
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}
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}
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#endif
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/**
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* Small animation that lets the dying snake disappear.
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* @param pprotSnake Pointer to the dying snake.
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*/
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static void snake_eliminateProtagonist(snake_protagonist_t *pprotSnake)
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{
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while (pprotSnake->nTailIndex != pprotSnake->nHeadIndex)
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{
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clearpixel(pprotSnake->aSegments[pprotSnake->nTailIndex++]);
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pprotSnake->nTailIndex %= USNAKE_MAX_LENGTH;
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wait(SNAKE_TERMINATION_DELAY);
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}
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}
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/**
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* Initializes the structure that keeps track of all currently existing apples.
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* @param pApples Pointer to the apples in question.
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*/
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static void snake_initApples(snake_apples_t *pApples)
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{
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pApples->nAppleCount = 0;
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}
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/**
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* Checks for an apple at a given position and removes it if there is one.
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* @param pApples The set of apples which are one the playing field
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* @param pxHead The position to be tested.
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* @return 0 if no apples were found, 1 otherwise
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*/
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static uint8_t snake_checkForApple(snake_apples_t *pApples, pixel pxHead)
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{
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for (uint8_t i = pApples->nAppleCount; i--;)
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{
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if ((pxHead.x == pApples->aApples[i].x) &&
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(pxHead.y == pApples->aApples[i].y))
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{
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for (; i < pApples->nAppleCount; ++i)
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{
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pApples->aApples[i] = pApples->aApples[i + 1];
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}
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--pApples->nAppleCount;
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return 1;
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}
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}
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return 0;
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}
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/**
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* Creates some new apples from time to time.
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* @param pApples Pointer to the apple structure.
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*/
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static void snake_spawnApples(snake_apples_t *pApples)
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{
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if ((pApples->nAppleCount < SNAKE_MAX_APPLES) && (random8() < 10))
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{
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pixel pxApple = (pixel){(random8() % (NUM_COLS-2)) + 1,
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(random8() % (NUM_ROWS - 2)) + 1};
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if (!get_pixel(pxApple))
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{
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pApples->aApples[pApples->nAppleCount++] = pxApple;
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}
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}
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}
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/**
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* The snake game.
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*/
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void snake_engine(uint8_t bDemoMode)
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{
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// init
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snake_protagonist_t protSnake;
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snake_initGameProtagonist(&protSnake);
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snake_apples_t apples;
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snake_initApples(&apples);
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snake_dir_t dirLast = SNAKE_DIR_NONE;
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// init screen
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clear_screen(0);
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snake_drawBorder();
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for (uint8_t nAppleColor = 0; 1; nAppleColor ^= SNAKE_COLOR_APPLE)
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{
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// determine new direction
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#if defined ANIMATION_SNAKE && defined GAME_SNAKE
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if (bDemoMode)
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{
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snake_autoRoute(&protSnake, &apples);
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}
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else
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{
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snake_userControl(&protSnake, &dirLast);
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}
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#elif defined ANIMATION_SNAKE
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snake_autoRoute(&protSnake, &apples);
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#else
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snake_userControl(&protSnake, &dirLast);
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#endif
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// actually move head
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pixel pxOldHead = protSnake.aSegments[protSnake.nHeadIndex];
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protSnake.nHeadIndex = (protSnake.nHeadIndex + 1) % USNAKE_MAX_LENGTH;
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protSnake.aSegments[protSnake.nHeadIndex] =
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snake_applyDirection(pxOldHead, protSnake.dir);
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// look if we have found an apple
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if (!snake_checkForApple(&apples,
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protSnake.aSegments[protSnake.nHeadIndex]))
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{
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// quit game if we hit something which is not an apple
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if (get_pixel(protSnake.aSegments[protSnake.nHeadIndex]))
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{
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snake_eliminateProtagonist(&protSnake);
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return;
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}
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// remove last segment
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clearpixel(protSnake.aSegments[protSnake.nTailIndex])
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protSnake.nTailIndex = (protSnake.nTailIndex +1) % USNAKE_MAX_LENGTH;
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// new apples
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snake_spawnApples(&apples);
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}
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// draw new head
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setpixel(protSnake.aSegments[protSnake.nHeadIndex],
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SNAKE_COLOR_PROTAGONIST);
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// draw apples
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for (uint8_t i = apples.nAppleCount; i--;)
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{
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setpixel(apples.aApples[i], nAppleColor);
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}
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wait(SNAKE_CYCLE_DELAY);
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}
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}
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/**
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* Snake in game mode.
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*/
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void snake_game(void)
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{
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snake_engine(0);
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}
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