borgware-2d/animations/flyingdots.c

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2009-12-27 00:55:03 +00:00
#include <inttypes.h>
#include "../config.h"
#include "../random/prng.h"
#include "../pixel.h"
#include "../util.h"
//dots flying from left to right
void flyingdots()
{
uint8_t rowbuffer[NUM_ROWS], i, j;
pixel p;
clear_screen(0);
//set the pixels to the leftmost columns
p.x = NUM_COLS-1;
//clear rowbuffer
for(i = 0; i < NUM_ROWS; i++)
{
rowbuffer[i] = 0;
}
//produce 200 dots
for (i = 0; i < 200; i++)
{
//the idea is to use a buffer for one row
//first all pixels that are in the rowbuffer
//will be reduced in brightness
//(as you can assume that they were
// drawn in the last round and need to be dimmed
// to produce the trail effect)
//and then a new one will be added
//finally the rowbuffer is drawn
//loop through all pixels in our rowbuffer
for(j = 0; j < NUM_ROWS; j++)
{
//add a trail or remove the pixel, if it was bright enough
if(rowbuffer[j] > 0)
{
rowbuffer[j]--;
}
}
//choose row and brightness
p.y = random8() % NUM_ROWS;
rowbuffer[p.y] += (random8() % (NUMPLANE)) + 1;
//cap max brightness
if(rowbuffer[p.y] > NUMPLANE)
{
rowbuffer[p.y] = NUMPLANE;
}
//draw all pixels in our rowbuffer
for(j = 0; j < NUM_ROWS; j++)
{
if(rowbuffer[j] > 0)
{
p.y = j;
setpixel(p, rowbuffer[j]);
}
}
//shift the picture right
//(yes, shift_pixmap_l shifts the picture right)
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shift_pixmap_l();
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//wait a bit
wait(100);
}
}