void Graph::halfTone(Color color){
int megaPixel = 3;
Vector v;
Color tmp;
int numberOfPixels;
//backup before doing half-toning
backupPixelBuffer();
for(int r = 0 ; r < window_height; r+=megaPixel){ //row
for(int c = 0 ; c < window_width; c+=megaPixel){//col
v = {0,0,0};
for(int i = r; i < r+megaPixel ; i++){ // 3 by 3
for(int j = c; j < c+megaPixel; j++ ){
//DPRINT("r %d, c %d, i %d, j %d\n", r, c, i,j);
tmp = readPixel(j,i);
if( equal(tmp, background_color) )
v = add( v, {1, 1, 1} );
else
v = add( v, ctov( tmp ) );
}
}
//write each mega pixel
numberOfPixels = round( 9- (v.x + v.y + v.z) / 3 );
drawMegaPixel(numberOfPixels, megaPixel * 3, r, c, color);
}
}
}
void calculate_intensity(struct vector *c,
struct constants *k,
color ambient,
struct light *light,
struct vector *p,
struct vector *n,
struct vector *v) {
/* I = Ke + Ia Ka + Ip Kd (->L * ->N) + Ip Ks [(2->N(->L * ->N)- ->L) * ->V] */
double dotd, dots;
struct vector l, tmp;
l = *p;
subtract_vectors(&l, &light->l);
normalize(&l);
dotd = dot(&l, n);
if (dotd < 0) {
dotd = dots = 0;
goto add_terms;
}
tmp = *n;
scalar_mult(2 * dotd, &tmp);
subtract_vectors(&tmp, &l);
dots = dot(&tmp, v);
if (dots < 0)
dots = 0;
add_terms:
ctov(c, k->e);
ctov(&tmp, ambient);
tmp.x *= k->r[Ka];
tmp.y *= k->g[Ka];
tmp.z *= k->b[Ka];
add_vectors(c, &tmp);
ctov(&tmp, light->c);
tmp.x *= k->r[Kd] * dotd + k->r[Ks] * dots;
tmp.y *= k->g[Kd] * dotd + k->g[Kd] * dots;
tmp.z *= k->b[Kd] * dotd + k->b[Ks] * dots;
add_vectors(c, &tmp);
}
