graph2.cpp

#include <bios.h>

/*
 * Graphic library for DOS
 * By Caiwan / Industrial Revolutioners
 *
*/

typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;

// sets 13h video mode (320x200)
void initgraph(){
    asm{
        mov ax, 13h
        int 10h
    }
}

// sets 10h default mode to text
void closegraph(){
    asm{
        mov ax, 10h
        int 10h
    }
}

//puts a pixel to a VRAM offset
void putpixel(ushort offs, uchar p){
    if (offs >= 320*200) return;
    asm {
        mov di, offs
        mov ax, 0xA000

        mov es, ax

        xor cx, cx
        xor ax, ax
        mov al, p

        stosb
    }
}

//puts a pixel to a specified xy coord
void putpixel(ushort x, ushort y, uchar p){
    putpixel (320*y+x, p);
}

//sets a palette token to a specified RGB color
void setpalette(uchar p, uchar r, uchar g, uchar b) {
    asm {
        xor bx, bx
        xor dx, dx
        xor cx, cx

        mov bl, p
        mov dh, r
        mov cl, g
        mov ch, b

        mov ax, 1010h
        int 10h
    }
}

/*
 * MAIN FUNCTION
 *
*/

#include <math.h>

int main(){
    // init graph
    initgraph();

    // generate a grazscale palette
    for (uchar i=0; i<255; i++){
        setpalette (i, i >> 2, i >> 1, i);
    }

    ushort kesz = 0;
    float t = 0.0f;
    do {
        float k = 1.5f*(1.1f+sin(t));
        float ca = cos(.5*k+t);
        float sa = sin(.5*k+t);

        for (ushort x = 0; x<320; x++)
            for(ushort y = 0; y<200; y++){

                float _x = ((float)x-160) * k;
                float _y = ((float)y-100) * k;

                float __x = ca * _x - sa * _y;
                float __y = sa * _x + ca * _y;

                uchar xx = (uchar)__x;
                uchar yy = (uchar)__y;

                uchar tx = xx^yy;

                putpixel(x, y, tx);
            }

        t += 0.1f;

        kesz = !_bios_keybrd(_KEYBRD_READY);
    } while (kesz);

    // release graphics and get back to DOS
    closegraph();
    return 0;
}