mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-09-11 09:54:37 +00:00
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
|
|
/*
|
|
This demo draws pixels and lines in Mode 2.
|
|
Note that when lines of two different colors overlap,
|
|
they create "clashing" effects.
|
|
*/
|
|
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
#include <cv.h>
|
|
#include <cvu.h>
|
|
|
|
#include "common.h"
|
|
|
|
void setup_mode2() {
|
|
cvu_vmemset(0, 0, 0x4000);
|
|
cv_set_screen_mode(CV_SCREENMODE_BITMAP); // mode 2
|
|
cv_set_image_table(IMAGE);
|
|
cv_set_character_pattern_t(PATTERN|0x1fff); // AND mask
|
|
cv_set_color_table(COLOR|0x1fff); // AND mask
|
|
cv_set_sprite_attribute_table(0x2800);
|
|
{
|
|
byte i=0;
|
|
do {
|
|
cvu_voutb(i, IMAGE+i);
|
|
cvu_voutb(i, IMAGE+0x100+i);
|
|
cvu_voutb(i, IMAGE+0x200+i);
|
|
} while (++i);
|
|
}
|
|
}
|
|
|
|
void set_pixel(byte x, byte y, byte color) {
|
|
word ofs = (x/8)*8 + (y/8)*256 + (y&7);
|
|
byte b = cvu_vinb(PATTERN + ofs);
|
|
if (y >= 192) return;
|
|
if (color>1) {
|
|
b |= 128 >> (x&7);
|
|
cvu_voutb(b, PATTERN + ofs);
|
|
cvu_voutb(color<<4, COLOR + ofs);
|
|
} else {
|
|
b &= ~(128 >> (x&7));
|
|
cvu_voutb(b, PATTERN + ofs);
|
|
}
|
|
}
|
|
|
|
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; }
|
|
}
|
|
}
|
|
|
|
#ifdef __MAIN__
|
|
|
|
void main() {
|
|
setup_mode2();
|
|
cv_set_screen_active(true);
|
|
while(1) {
|
|
draw_line(rand()&0xff, rand()&0xbf, rand()&0xff, rand()&0xbf, rand()&15);
|
|
}
|
|
}
|
|
|
|
#endif
|