95 lines
1.8 KiB
C
95 lines
1.8 KiB
C
#include <string.h>
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#include <c64/vic.h>
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#include <c64/memmap.h>
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#include <conio.h>
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// Address of hires buffer and color buffers
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#define Screen ((char *)0xe000)
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#define Color ((char *)0xc800)
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#define Color2 ((char *)0xd800)
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// Bit patters for eight different color pairs
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char colors[] = {
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0xff, 0xff,
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0xee, 0xbb,
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0xaa, 0xaa,
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0x88, 0x22,
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0x44, 0x11,
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0x55, 0x55,
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0xdd, 0x77,
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0x33, 0xcc
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};
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int main(void)
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{
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// Install the IRQ trampoline
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mmap_trampoline();
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// Turn of the kernal ROM
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mmap_set(MMAP_NO_ROM);
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// Switch VIC into multicolor bitmap mode
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vic_setmode(VICM_HIRES_MC, Color, Screen);
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// Clear the screen and set the colors
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vic.color_back = 0x00;
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memset(Screen, 0, 8000);
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memset(Color, 0x27, 1000);
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memset(Color2, 0x03, 1000);
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// Loop over all pixels
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int py, px;
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for(py=0; py<100; py++)
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{
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for(px=0; px<160; px++)
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{
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// Value in the complex plane
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float xz = (float)px * (3.5 / 160.0)- 2.5;
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float yz = (float)py * (2.4 / 100.0) - 1.2;
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// Iterate up to 32 times
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float x = 0.0, y = 0.0;
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int i;
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for(i=0; i<32; i++)
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{
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if (x * x + y * y > 4.0) break;
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float xt = x * x - y * y + xz;
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y = 2 * x * y + yz;
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x = xt;
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}
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if (i < 32)
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{
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// Position on screen
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char * dp = Screen + 320 * (py >> 2) + 2 * (py & 3) + 2 * (px & ~3);
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// Mask of pixels to change
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char mask = 0xc0 >> (2 * (px & 3));
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// Get the two color patterns for upper and lower half
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char c0 = colors[2 * (i & 7)], c1 = colors[2 * (i & 7) + 1];
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// Put the pixels into the image
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dp[0] |= c0 & mask;
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dp[1] |= c1 & mask;
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}
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}
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}
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// Re-enable the kernal
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mmap_set(MMAP_NO_BASIC);
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// Wait for key press
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getch();
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// Restore VIC state
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vic_setmode(VICM_TEXT, (char *)0x0400, (char *)0x1000);
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return 0;
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}
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