void drawSet(double zoom_factor, double offset)
{
clock_t start = clock();
/* (x,y) is the pixel coordinate with respect to the center (x0,y0)
(xp,yp) is the pixel coordinate with respect to the image corner. */
double xp, yp, r, g, b;
int iteration = 0;
struct complex c;
int color;
/* Complex plane scaling */
double xp_max = ( 1.25 * scaleX - offset ) / zoom_factor;
double xp_min = ( -1.75 * scaleX - offset ) / zoom_factor;
double yp_max = ( 1.5 * scaleY - offset ) / zoom_factor;
double yp_min = ( -1.5 * scaleY - offset ) / zoom_factor;
// Lock surface if needed
if (SDL_MUSTLOCK(screen))
if (SDL_LockSurface(screen) < 0)
return;
for (xp = 0; xp < sizeX; xp++)
{
for (yp = 0; yp < sizeY; yp++)
{
/* Scaling */
c.real = ( (xp_max - xp_min) * xp ) / sizeX + xp_min;
c.imag = ( (yp_max - yp_min) * yp ) / sizeY + yp_min;
// printf("x is: %f, y is: %f\n", x, y);
iteration = mandelbrotCalc(c);
// printf("iteration: %d\n", iteration);
/* Define the color sets that are going to be used. */
if (iteration > max_iteration) {
color = 0x000000;
} else {
double i = (iteration * 255 / max_iteration);
r = round(sin(0.2 * i + 0) * 127 + 128);
g = round(sin(0.2 * i + 2) * 127 + 128);
b = round(sin(0.2 * i + 4) * 127 + 128);
color = createRGB(r,g,b);
}
putpixel(xp,yp,color);
iteration = 0;
}
}
// Unlock if needed
if (SDL_MUSTLOCK(screen))
SDL_UnlockSurface(screen);
// update the whole screen
SDL_UpdateRect(screen, 0, 0, sizeX, sizeY);
clock_t end = clock();
clock_t millis = end - start;
printf("Elapsed time: %lu\n", millis);
}
int escapeSteps (double x, double y) {
Complex c = {x, y};
Complex z = {0, 0};
int steps = 0;
while (magnitude (z) <= 4 && steps < MAX_STEPS) {
z = mandelbrotCalc(z,c);
steps ++;
}
return steps;
}