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#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <time.h>
#include <sys/types.h>
#include <unistd.h>
#include <math.h>
#include "draw.h"
#include "fb.h"
#include "rototiller.h"
/* Copyright (C) 2017-19 Philip J. Freeman <elektron@halo.nu> */
struct points
{
float x, y, z;
struct points *next;
};
typedef struct stars_context_t {
struct points* points;
} stars_context_t;
float get_random_unit_coord() {
return (((float)rand()/(float)RAND_MAX)*2.0)-1.0;
}
static void * stars_create_context(unsigned num_cpus)
{
stars_context_t *ctxt;
float z;
struct points* p_ptr = NULL;
ctxt = malloc(sizeof(stars_context_t));
if (!ctxt)
return NULL;
ctxt->points = NULL;
//add a bunch of points
for(z=0.01; z<1; z=z+0.01) {
for(int i=0; i<rand()%16; i++){
p_ptr = malloc(sizeof(struct points));
if (!p_ptr)
return NULL;
p_ptr->x = get_random_unit_coord();
p_ptr->y = get_random_unit_coord();
p_ptr->z = z;
p_ptr->next = ctxt->points;
ctxt->points = p_ptr;
}
}
return ctxt;
}
static void stars_destroy_context(void *context)
{
stars_context_t *ctxt = context;
struct points* p_ptr;
struct points* last_ptr=NULL;
for ( p_ptr=ctxt->points; p_ptr != NULL; p_ptr = p_ptr->next)
{
if (last_ptr!=NULL)
free(last_ptr);
last_ptr=p_ptr;
}
free(last_ptr);
free(context);
}
static void stars_render_fragment(void *context, unsigned cpu, fb_fragment_t *fragment)
{
stars_context_t *ctxt = context;
struct points* iterator;
struct points* tmp_ptr;
struct points* last_ptr=NULL;
float x, y, pos_x, pos_y, opacity;
int width = fragment->width, height = fragment->height;
float max_radius=1.f+((width+height)*.001f);
fb_fragment_zero(fragment);
iterator=ctxt->points;
for(;;)
{
if(iterator == NULL)
break;
if(iterator->z >= 1) {
if(last_ptr == NULL)
ctxt->points = iterator->next;
else
last_ptr->next = iterator->next;
tmp_ptr = iterator;
iterator = iterator->next;
free(tmp_ptr);
continue;
}
x = iterator->x / (1.f - iterator->z);
y = iterator->y / (1.f - iterator->z);
pos_x = ((x+1.f)*.5f)*(float)width;
pos_y = ((y+1.f)*.5f)*(float)height;
if(iterator->z<0.1)
opacity = iterator->z*10;
else
opacity = 1;
if (pos_x>0 && pos_x<width && pos_y>0 && pos_y<height)
fb_fragment_put_pixel_unchecked(fragment, pos_x, pos_y,
makergb(0xFF, 0xFF, 0xFF, opacity));
for(int my_y=floorf(pos_y-max_radius); my_y<=ceilf(pos_y+max_radius); my_y++)
for(int my_x=floorf(pos_x-max_radius); my_x<=ceilf(pos_x+max_radius); my_x++) {
//Is the point within our viewing window?
if (!(my_x>0 && my_x<width && my_y>0 && my_y<height))
continue;
//Is the point within the circle?
if(powf(my_x-pos_x, 2)+powf(my_y-pos_y, 2) > powf((iterator->z*max_radius), 2))
continue;
fb_fragment_put_pixel_unchecked(fragment, my_x, my_y,
makergb(0xFF, 0xFF, 0xFF, opacity));
}
iterator->z += 0.01;
last_ptr=iterator;
iterator=iterator->next;
}
// add stars at horizon
for(int i=0; i<rand()%16; i++){
tmp_ptr = malloc(sizeof(struct points));
if (!tmp_ptr)
break;
tmp_ptr->x = get_random_unit_coord();
tmp_ptr->y = get_random_unit_coord();
tmp_ptr->z = 0.01;
tmp_ptr->next = ctxt->points;
ctxt->points = tmp_ptr;
}
}
rototiller_module_t stars_module = {
.create_context = stars_create_context,
.destroy_context = stars_destroy_context,
.render_fragment = stars_render_fragment,
.name = "stars",
.description = "Basic starfield",
.author = "Philip J Freeman <elektron@halo.nu>",
.license = "GPLv2",
};
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