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8bitworkshop/presets/nes/metasprites.c
2019-07-29 11:22:00 -04:00

99 lines
2.2 KiB
C

/*
Metasprites combine several hardware sprites to make a larger
sprite. Our demo uses 4 hardware sprites in a 2x2 pattern,
forming 16x16 pixel sprites.
*/
#include <stdlib.h>
#include <string.h>
// include NESLIB header
#include "neslib.h"
// include CC65 NES Header (PPU)
#include <nes.h>
// link the pattern table into CHR ROM
//#link "chr_generic.s"
///// METASPRITES
#define TILE 0xd8
#define ATTR 0
// define a 2x2 metasprite
const unsigned char metasprite[]={
0, 0, TILE+0, ATTR,
0, 8, TILE+1, ATTR,
8, 0, TILE+2, ATTR,
8, 8, TILE+3, ATTR,
128};
/*{pal:"nes",layout:"nes"}*/
const char PALETTE[32] = {
0x03, // screen color
0x11,0x30,0x27,0x0, // background palette 0
0x1c,0x20,0x2c,0x0, // background palette 1
0x00,0x10,0x20,0x0, // background palette 2
0x06,0x16,0x26,0x0, // background palette 3
0x16,0x35,0x24,0x0, // sprite palette 0
0x00,0x37,0x25,0x0, // sprite palette 1
0x0d,0x2d,0x3a,0x0, // sprite palette 2
0x0d,0x27,0x2a // sprite palette 3
};
// setup PPU and tables
void setup_graphics() {
// clear sprites
oam_clear();
// set palette colors
pal_all(PALETTE);
// turn on PPU
ppu_on_all();
}
// number of actors (4 h/w sprites each)
#define NUM_ACTORS 16
// actor x/y positions
byte actor_x[NUM_ACTORS];
byte actor_y[NUM_ACTORS];
// actor x/y deltas per frame (signed)
sbyte actor_dx[NUM_ACTORS];
sbyte actor_dy[NUM_ACTORS];
// main program
void main() {
char i; // actor index
char oam_id; // sprite ID
// initialize PPU
setup_graphics();
// initialize actors with random values
for (i=0; i<NUM_ACTORS; i++) {
actor_x[i] = rand();
actor_y[i] = rand();
actor_dx[i] = (rand() & 7) - 3;
actor_dy[i] = (rand() & 7) - 3;
}
// loop forever
while (1) {
// start with OAMid/sprite 0
oam_id = 0;
// draw and move all actors
for (i=0; i<NUM_ACTORS; i++) {
oam_id = oam_meta_spr(actor_x[i], actor_y[i], oam_id, metasprite);
actor_x[i] += actor_dx[i];
actor_y[i] += actor_dy[i];
}
// hide rest of sprites
// if we haven't wrapped oam_id around to 0
if (oam_id!=0) oam_hide_rest(oam_id);
// wait for next frame
ppu_wait_frame();
}
}