mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-23 06:32:11 +00:00
145 lines
3.1 KiB
C
145 lines
3.1 KiB
C
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <c64.h>
|
|
#include <peekpoke.h>
|
|
|
|
#include "common.h"
|
|
//#link "common.c"
|
|
|
|
void setup_bitmap_multi() {
|
|
VIC.ctrl1 = 0x38;
|
|
VIC.ctrl2 = 0x18;
|
|
// set VIC bank ($4000-$7FFF)
|
|
// https://www.c64-wiki.com/wiki/VIC_bank
|
|
CIA2.pra = 0x02;
|
|
// set VIC screen to $6000
|
|
VIC.addr = 0x80;
|
|
// clear bitmap and screen RAM
|
|
memset((void*)0x4000, 0, 0x2000);
|
|
memset((void*)0xd800, 0, 40*25);
|
|
}
|
|
|
|
const byte PIXMASK[4] = { ~0xc0, ~0x30, ~0x0c, ~0x03 };
|
|
const byte PIXSHIFT[4] = { 6, 4, 2, 0 };
|
|
|
|
byte is_pixel(byte x, byte y) {
|
|
word ofs = ((x>>2)*8 + (y>>3)*320) | (y&7) | 0x4000;
|
|
return PEEK(ofs) & ~PIXMASK[x & 3];
|
|
}
|
|
|
|
void set_pixel(byte x, byte y, byte color) {
|
|
word ofs,b,cram,sram;
|
|
byte ccol,scol;
|
|
byte val;
|
|
|
|
if (x >= 160 || y >= 192) return;
|
|
|
|
color &= 0xf;
|
|
// equal to background color? (value 0)
|
|
if (color == VIC.bgcolor0) {
|
|
val = 0;
|
|
} else {
|
|
cram = ((x>>2) + (y>>3)*40);
|
|
sram = cram | 0x6000;
|
|
cram |= 0xd800;
|
|
ccol = PEEK(cram);
|
|
scol = PEEK(sram);
|
|
// color RAM contains unused bits (0x10 and 0x20)
|
|
// unused in lower nibble of screen RAM? (value 2)
|
|
if (color == (scol & 0xf) || !(ccol & 0x10)) {
|
|
val = 2;
|
|
scol = (scol & 0xf0) | color;
|
|
ccol |= 0x10;
|
|
POKE(sram, scol);
|
|
// unused in upper nibble of screen RAM? (value 1)
|
|
} else if (color == (scol >> 4) || !(ccol & 0x20)) {
|
|
val = 1;
|
|
scol = (scol & 0xf) | (color << 4);
|
|
ccol |= 0x20;
|
|
POKE(sram, scol);
|
|
// all other colors in use, use color RAM
|
|
} else {
|
|
val = 3;
|
|
ccol = 0x30 | color;
|
|
}
|
|
POKE(cram, ccol);
|
|
}
|
|
|
|
ofs = ((x>>2)*8 + (y>>3)*320) | (y&7) | 0x4000;
|
|
x &= 3;
|
|
b = PEEK(ofs) & PIXMASK[x];
|
|
if (val) {
|
|
b |= val << PIXSHIFT[x];
|
|
}
|
|
POKE(ofs, b);
|
|
}
|
|
|
|
void draw_line(int x0, int y0, int x1, int y1, byte color) {
|
|
int dx = abs(x1-x0);
|
|
int sx = x0<x1 ? 1 : -1;
|
|
int dy = abs(y1-y0);
|
|
int sy = y0<y1 ? 1 : -1;
|
|
int err = (dx>dy ? dx : -dy)>>1;
|
|
int e2;
|
|
for(;;) {
|
|
set_pixel(x0, y0, color);
|
|
if (x0==x1 && y0==y1) break;
|
|
e2 = err;
|
|
if (e2 > -dx) { err -= dy; x0 += sx; }
|
|
if (e2 < dy) { err += dx; y0 += sy; }
|
|
}
|
|
}
|
|
|
|
#pragma static-locals(push,off)
|
|
byte flood_fill(byte x, byte y, byte color) {
|
|
register byte x1 = x;
|
|
register byte x2;
|
|
register byte i;
|
|
// find left edge
|
|
while (!is_pixel(x1, y))
|
|
--x1;
|
|
// exit if (x,y) is on a boundary
|
|
if (x1 == x)
|
|
return 1;
|
|
++x1;
|
|
// find right edge
|
|
x2 = x+1;
|
|
while (!is_pixel(x2, y))
|
|
++x2;
|
|
// fill scanline
|
|
for (i=x1; i<x2; i++) {
|
|
set_pixel(i, y, color);
|
|
}
|
|
// fill above and below scanline
|
|
for (i=x1; i<x2; ) {
|
|
i += flood_fill(i, y-1, color);
|
|
}
|
|
for (i=x1; i<x2; ) {
|
|
i += flood_fill(i, y+1, color);
|
|
}
|
|
return (x2-x1);
|
|
}
|
|
#pragma static-locals(pop)
|
|
|
|
#ifdef __MAIN__
|
|
|
|
word urand() {
|
|
return rand();
|
|
}
|
|
|
|
void main() {
|
|
setup_bitmap_multi();
|
|
draw_line(80, 10, 100, 100, 1);
|
|
draw_line(80, 10, 40, 80, 1);
|
|
draw_line(100, 100, 40, 80, 1);
|
|
draw_line(50, 0, 80, 60, 1);
|
|
draw_line(100, 0, 80, 60, 1);
|
|
flood_fill(80, 80, 2);
|
|
while(1) {
|
|
draw_line(urand()%160, urand()%192, urand()%160, urand()%192, rand()&15);
|
|
}
|
|
}
|
|
|
|
#endif
|