/**
* @brief Generates an filled circle texture.
*
* @param radius Radius of the circle to generate.
* @return The tetxure containing the generated circle.
*/
static glTexture *gl_genCircle( int radius )
{
int i,j,k, n,m;
SDL_Surface *sur;
uint8_t *pix, *buf;
int h, w;
double a;
/* Calculate parameters. */
w = 2*radius+1;
h = 2*radius+1;
/* Create the surface. */
sur = SDL_CreateRGBSurface( SDL_SWSURFACE, w, h, 32, RGBAMASK );
pix = sur->pixels;
/* Generate the circle. */
SDL_LockSurface( sur );
/* Create temporary buffer to draw circle in. */
k = 3;
buf = malloc( (h*k) * (w*k) );
for (i=0; i<k*h; i++) {
for (j=0; j<k*w; j++) {
if (pow2(i-k*radius)+pow2(j-k*radius) < pow2(k*radius))
buf[ i*k*w + j] = 0xFF;
}
}
/* Draw the circle with filter. */
for (i=0; i<h; i++) {
for (j=0; j<w; j++) {
/* Calculate blur. */
a = 0.;
for (n=0; n<k; n++) {
for (m=0; m<k; m++) {
a += buf[ (i*k+n)*k*w + (j*k+m) ];
}
}
a /= k*k;
/* Set pixel. */
pix[i*sur->pitch + j*4 + 0] = 0xFF;
pix[i*sur->pitch + j*4 + 1] = 0xFF;
pix[i*sur->pitch + j*4 + 2] = 0xFF;
pix[i*sur->pitch + j*4 + 3] = (uint8_t)a;
}
}
/* CLean up. */
free(buf);
SDL_UnlockSurface( sur );
/* Return texture. */
return gl_loadImage( sur, OPENGL_TEX_MIPMAPS );
}
/**
* @brief Generates a texture to represent factions
*
* @param radius radius of the disk
* @return the texture
*/
static glTexture *gl_genFactionDisk( int radius )
{
int i, j;
uint8_t *pixels;
SDL_Surface *sur;
int dist;
double alpha;
/* Calculate parameters. */
const int w = 2 * radius + 1;
const int h = 2 * radius + 1;
/* Create the surface. */
sur = SDL_CreateRGBSurface( SDL_SRCALPHA | SDL_HWSURFACE, w, h, 32, RGBAMASK );
pixels = sur->pixels;
memset(pixels, 0xff, sizeof(uint8_t) * 4 * h * w);
/* Generate the circle. */
SDL_LockSurface( sur );
/* Draw the circle with filter. */
for (i=0; i<h; i++) {
for (j=0; j<w; j++) {
/* Calculate blur. */
dist = (i - radius) * (i - radius) + (j - radius) * (j - radius);
alpha = 0.;
if (dist < radius * radius) {
/* Computes alpha with an empirically chosen formula.
* This formula accounts for the fact that the eyes
* has a logarithmic sensitivity to light */
alpha = 1. * dist / (radius * radius);
alpha = (exp(1 / (alpha + 1) - 0.5) - 1) * 0xFF;
}
/* Sets the pixel alpha which is the forth byte
* in the pixel representation. */
pixels[i*sur->pitch + j*4 + 3] = (uint8_t)alpha;
}
}
SDL_UnlockSurface( sur );
/* Return texture. */
return gl_loadImage( sur, OPENGL_TEX_MIPMAPS );
}
/**
* @brief Generates nebula puffs.
*/
static void nebu_generatePuffs (void)
{
int i;
int w,h;
SDL_Surface *sur;
float *nebu;
/* Warn user of what is happening. */
loadscreen_render( 0.05, "Generating Nebula Puffs..." );
/* Generate the nebula puffs */
for (i=0; i<NEBULA_PUFFS; i++) {
/* Generate the nebula */
w = h = RNG(20,64);
nebu = noise_genNebulaPuffMap( w, h, 1. );
sur = nebu_surfaceFromNebulaMap( nebu, w, h );
free(nebu);
/* Load the texture */
nebu_pufftexs[i] = gl_loadImage( sur, 0 );
}
}