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#include "SDL.h"
#include "SDL_gfxPrimitives.h"
#include <stdlib.h>
#include "starfield.h"
#include "random.h"
#include "util.h"
#define VERTICAL_VELOCITY 0
StarField :: StarField( bool side, int nStars, int mx, int my, int minz, int maxz )
{
nrStars = nStars;
maxX = mx;
maxY = my;
minZ = minz;
maxZ = maxz;
min_brightness = 50;
top_star_speed = 6;
sideways = side;
if ( !sideways )
{
x = new int[nrStars];
y = new int[nrStars];
z = new int[nrStars];
star_color = 0;
vel_x = 0;
vel_y = 0;
pos_x = 0;
pos_y = 0;
}
else
{
star_color = new int[nrStars];
vel_x = new int[nrStars];
vel_y = new int[nrStars];
pos_x = new int[nrStars];
pos_y = new int[nrStars];
x = 0;
y = 0;
z = 0;
}
init();
}
StarField :: ~StarField()
{
if ( star_color )
delete []star_color;
if ( vel_x )
delete []vel_x;
if ( vel_y )
delete []vel_y;
if ( pos_x )
delete []pos_x;
if ( pos_y )
delete []pos_y;
if ( x )
delete []x;
if ( y )
delete []y;
if ( z )
delete []z;
}
void StarField :: init()
{
if ( !sideways )
{
for ( int i = 0 ; i < nrStars ; ++i )
{
newStar( i );
z[i] = (int)(Random() * (double)(maxZ - minZ)) + minZ ;
}
}
else
{
int brightness;
//Initialise each star
for(int i = 0; i < nrStars ; i++)
{
//Inialise velocities
vel_x[i] = -(int)floor( (Random() * top_star_speed)+1 );
vel_y[i] = VERTICAL_VELOCITY;
//Initialise positions randomly
pos_x[i] = (int)floor((Random() * 240));
pos_y[i] = (int)floor((Random() * 320));
//The Faster it goes, the Dimmer it is
if (vel_x[i] != 0)
{
brightness = (int)(255 / fabs(vel_x[i]) );
if (brightness < min_brightness)
brightness = min_brightness;
}
else
brightness = 255;
star_color[i] = brightness;
}
}
}
void StarField :: newStar( int starNr )
{
if ( !sideways )
{
x[starNr] = (int)(Random() * (double)maxX) + 1;
y[starNr] = (int)(Random() * (double)maxY) + 1;
z[starNr] = maxZ;
int i = (int)(Random() * 4.0);
if(i < 2)
x[starNr] = -x[starNr];
if(i == 0 || i == 2)
y[starNr] = -y[starNr];
}
}
void StarField :: move( )
{
if ( !sideways )
{
int amountToMove = 16;
for(int i = 0; i < nrStars; i++)
{
// Rotate star
z[i] = z[i] - amountToMove;
if(z[i] < minZ)
newStar(i);
}
}
else
{
for(int i = 0; i < nrStars ; i++)
{
//Check speed limits x
if (vel_x[i] > top_star_speed)
vel_x[i] = top_star_speed;
else if (vel_x[i] < -top_star_speed)
vel_x[i] = -top_star_speed;
//Check speed limits y
if (vel_y[i] > top_star_speed)
vel_y[i] = top_star_speed;
else if (vel_y[i] < -top_star_speed)
vel_y[i] = -top_star_speed;
//Move Star
pos_x[i] += vel_x[i];
pos_y[i] += vel_y[i];
if (pos_x[i] < 0)
pos_x[i] = pos_x[i] + 240;
if (pos_x[i] > 240)
pos_x[i] = pos_x[i] - 240;
if (pos_y[i] < 0)
pos_y[i] = pos_y[i] + 320;
if (pos_y[i] > 320)
pos_y[i] = pos_y[i] - 320;
}
}
}
void StarField :: draw( SDL_Surface *screen, int w, int h )
{
if ( !sideways )
{
int scrW = w / 2;
int scrH = h / 2;
for(int i = 0; i < nrStars; i++)
{
int sx = (x[i] * 256) / z[i] + scrW;
int sy = (y[i] * 256) / z[i] + scrH;
if(sx < 0 || sx > w || sy < 0 || sy > h)
{
newStar(i);
}
else
{
int size = (z[i] * 3) / maxZ;
SDL_Rect r;
r.x = sx;
r.y = sy;
r.w = 3 - size;
r.h = 3 - size;
SDL_FillRect( screen, &r, SDL_MapRGB( screen->format, 255, 255, 255 ) );
}
}
}
else
{
SDL_LockSurface( screen );
for(int i = 0; i < nrStars ; i++)
{
Uint32 c = getpixel( screen, pos_x[i], pos_y[i] );
if ( c == 0 )
lineRGBA( screen, pos_x[i], pos_y[i], pos_x [i]+ vel_x[i], pos_y[i] + vel_y[i], star_color[i], star_color[i], star_color[i], 255 );
//*** NOTE : if the velocity of the stars never changes then the values such as 'pos_x[i] + vel_x[i]' could be precalculated for each star ***
}
SDL_UnlockSurface( screen );
}
}
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