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8bitworkshop/presets/nes/siegegame.c

327 lines
7.6 KiB
C
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/*
A character-based surround-the-opponent game.
Reads from nametable RAM to determine collisions, and also
to help the AI avoid walls.
*/
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#include <stdlib.h>
#include <string.h>
#include <nes.h>
#include <joystick.h>
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#include "neslib.h"
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// VRAM buffer module
#include "vrambuf.h"
//#link "vrambuf.c"
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// link the pattern table into CHR ROM
//#link "chr_generic.s"
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#define COLS 32
#define ROWS 27
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// read a character from VRAM.
// this is tricky because we have to wait
// for VSYNC to start, then set the VRAM
// address to read, then set the VRAM address
// back to the start of the frame.
byte getchar(byte x, byte y) {
// compute VRAM read address
word addr = NTADR_A(x,y);
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// result goes into rd
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byte rd;
// wait for VBLANK to start
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ppu_wait_nmi();
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// set vram address and read byte into rd
vram_adr(addr);
vram_read(&rd, 1);
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// scroll registers are corrupt
// fix by setting vram address
vram_adr(0x0);
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return rd;
}
void cputcxy(byte x, byte y, char ch) {
vrambuf_put(NTADR_A(x,y), &ch, 1);
}
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void cputsxy(byte x, byte y, const char* str) {
vrambuf_put(NTADR_A(x,y), str, strlen(str));
}
void clrscr() {
vrambuf_clear();
ppu_off();
vram_adr(0x2000);
vram_fill(0, 32*28);
vram_adr(0x0);
ppu_on_bg();
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}
////////// GAME DATA
typedef struct {
byte x;
byte y;
byte dir;
word score;
char head_attr;
char tail_attr;
int collided:1;
int human:1;
} Player;
Player players[2];
byte attract;
byte gameover;
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byte frames_per_move;
#define START_SPEED 12
#define MAX_SPEED 5
#define MAX_SCORE 7
///////////
const char BOX_CHARS[8] = { '+','+','+','+','-','-','!','!' };
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void draw_box(byte x, byte y, byte x2, byte y2, const char* chars) {
byte x1 = x;
cputcxy(x, y, chars[2]);
cputcxy(x2, y, chars[3]);
cputcxy(x, y2, chars[0]);
cputcxy(x2, y2, chars[1]);
while (++x < x2) {
cputcxy(x, y, chars[5]);
cputcxy(x, y2, chars[4]);
}
while (++y < y2) {
cputcxy(x1, y, chars[6]);
cputcxy(x2, y, chars[7]);
}
}
void draw_playfield() {
draw_box(1,2,COLS-2,ROWS-1,BOX_CHARS);
cputcxy(9,1,players[0].score+'0');
cputcxy(28,1,players[1].score+'0');
if (attract) {
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cputsxy(3,ROWS-1,"ATTRACT MODE - PRESS ENTER");
} else {
cputsxy(1,1,"PLYR1:");
cputsxy(20,1,"PLYR2:");
}
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}
typedef enum { D_RIGHT, D_DOWN, D_LEFT, D_UP } dir_t;
const char DIR_X[4] = { 1, 0, -1, 0 };
const char DIR_Y[4] = { 0, 1, 0, -1 };
void init_game() {
memset(players, 0, sizeof(players));
players[0].head_attr = '1';
players[1].head_attr = '2';
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players[0].tail_attr = 0x06;
players[1].tail_attr = 0x07;
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frames_per_move = START_SPEED;
}
void reset_players() {
players[0].x = players[0].y = 5;
players[0].dir = D_RIGHT;
players[1].x = COLS-6;
players[1].y = ROWS-6;
players[1].dir = D_LEFT;
players[0].collided = players[1].collided = 0;
}
void draw_player(Player* p) {
cputcxy(p->x, p->y, p->head_attr);
}
void move_player(Player* p) {
cputcxy(p->x, p->y, p->tail_attr);
p->x += DIR_X[p->dir];
p->y += DIR_Y[p->dir];
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if (getchar(p->x, p->y) != 0)
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p->collided = 1;
draw_player(p);
}
void human_control(Player* p) {
byte dir = 0xff;
byte joy;
joy = joy_read (JOY_1);
// start game if attract mode
if (attract && (joy & JOY_START_MASK))
gameover = 1;
// do not allow movement unless human player
if (!p->human) return;
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if (joy & JOY_LEFT_MASK) dir = D_LEFT;
if (joy & JOY_RIGHT_MASK) dir = D_RIGHT;
if (joy & JOY_UP_MASK) dir = D_UP;
if (joy & JOY_DOWN_MASK) dir = D_DOWN;
// don't let the player reverse
if (dir < 0x80 && dir != (p->dir ^ 2)) {
p->dir = dir;
}
}
byte ai_try_dir(Player* p, dir_t dir, byte shift) {
byte x,y;
dir &= 3;
x = p->x + (DIR_X[dir] << shift);
y = p->y + (DIR_Y[dir] << shift);
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if (x < COLS && y < ROWS && getchar(x, y) == 0) {
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p->dir = dir;
return 1;
} else {
return 0;
}
}
void ai_control(Player* p) {
dir_t dir;
if (p->human) return;
dir = p->dir;
if (!ai_try_dir(p, dir, 0)) {
ai_try_dir(p, dir+1, 0);
ai_try_dir(p, dir-1, 0);
} else {
ai_try_dir(p, dir-1, 0) && ai_try_dir(p, dir-1, 1+(rand() & 3));
ai_try_dir(p, dir+1, 0) && ai_try_dir(p, dir+1, 1+(rand() & 3));
ai_try_dir(p, dir, rand() & 3);
}
}
void flash_colliders() {
byte i;
// flash players that collided
for (i=0; i<56; i++) {
//cv_set_frequency(CV_SOUNDCHANNEL_0, 1000+i*8);
//cv_set_attenuation(CV_SOUNDCHANNEL_0, i/2);
if (players[0].collided) players[0].head_attr ^= 0x80;
if (players[1].collided) players[1].head_attr ^= 0x80;
vrambuf_flush();
vrambuf_flush();
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draw_player(&players[0]);
draw_player(&players[1]);
}
//cv_set_attenuation(CV_SOUNDCHANNEL_0, 28);
}
void make_move() {
byte i;
for (i=0; i<frames_per_move; i++) {
human_control(&players[0]);
vrambuf_flush();
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}
ai_control(&players[0]);
ai_control(&players[1]);
// if players collide, 2nd player gets the point
move_player(&players[1]);
move_player(&players[0]);
}
void declare_winner(byte winner) {
byte i;
clrscr();
for (i=0; i<ROWS/2-3; i++) {
draw_box(i,i,COLS-1-i,ROWS-1-i,BOX_CHARS);
vrambuf_flush();
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}
cputsxy(12,10,"WINNER:");
cputsxy(12,13,"PLAYER ");
cputcxy(12+7, 13, '1'+winner);
vrambuf_flush();
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delay(75);
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gameover = 1;
}
#define AE(tl,tr,bl,br) (((tl)<<0)|((tr)<<2)|((bl)<<4)|((br)<<6))
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// this is attribute table data,
// each 2 bits defines a color palette
// for a 16x16 box
const unsigned char Attrib_Table[0x40]={
AE(3,3,1,0),AE(3,3,0,0),AE(3,3,0,0),AE(3,3,0,0), AE(2,2,0,0),AE(2,2,0,0),AE(2,2,0,0),AE(2,2,0,1),
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AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,0,1,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0), AE(0,0,0,0),AE(0,0,0,0),AE(0,0,0,0),AE(0,1,0,1),
AE(1,1,1,1),AE(1,1,1,1),AE(1,1,1,1),AE(1,1,1,1), AE(1,1,1,1),AE(1,1,1,1),AE(1,1,1,1),AE(1,1,1,1),
};
/*{pal:"nes",layout:"nes"}*/
const unsigned char Palette_Table[16]={
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0x00,
0x01,0x28,0x31,0x00,
0x04,0x24,0x34,0x00,
0x09,0x29,0x39,0x00,
0x06,0x26,0x36
};
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// put 8x8 grid of palette entries into the PPU
void setup_attrib_table() {
vram_adr(0x23c0);
vram_write(Attrib_Table, 0x40);
}
void setup_palette() {
int i;
// only set palette entries 0-15 (background only)
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for (i=0; i<16; i++)
pal_col(i, Palette_Table[i] ^ attract);
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}
void play_round() {
ppu_off();
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setup_attrib_table();
setup_palette();
clrscr();
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draw_playfield();
reset_players();
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while (1) {
make_move();
if (gameover) return; // attract mode -> start
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if (players[0].collided || players[1].collided) break;
}
flash_colliders();
// add scores to players that didn't collide
if (players[0].collided) players[1].score++;
if (players[1].collided) players[0].score++;
// increase speed
if (frames_per_move > MAX_SPEED) frames_per_move--;
// game over?
if (players[0].score != players[1].score) {
if (players[0].score >= MAX_SCORE)
declare_winner(0);
else if (players[1].score >= MAX_SCORE)
declare_winner(1);
}
}
void play_game() {
gameover = 0;
init_game();
if (!attract)
players[0].human = 1;
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while (!gameover) {
play_round();
}
}
void main() {
joy_install (joy_static_stddrv);
vrambuf_clear();
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set_vram_update(updbuf);
while (1) {
attract = 1;
play_game();
attract = 0;
play_game();
}
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}