julia.c File Reference

#include "fractol.h"

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Functions
static void	julia_iterations (t_render_vars *vars, t_data *data)
	Performs the iterations for a signle point in the Julia set.
static void	render_julia_row (t_render_vars *vars, t_data *data, int y)
	Renders a single row of the Julia set.
void	render_julia (t_data *data)
	Renders the Julia set fractal.

Function Documentation

julia_iterations()

static void julia_iterations ( t_render_vars *  vars, t_data *  data  )

static

Performs the iterations for a signle point in the Julia set.

This function applies the Julia set formula iteratively to determine whether a given point escapes the threshold. The number of iterations taken before escape determines the point's color.

• Core Algorithm: The formula z = z^2 + c is applied, where:
  • z is a complex number, represented by real (z_re) and imaginary (z_im) parts.
  • c is a constant defined by the user (real and imaginary parts).
• Bounding Condition: The iteerations stop when:
  • The sum of the squares of the real and imaginary parts exceeds 4.0.
  • The maximum number of iterations (MAX_ITERATIONS) is reached.
• Optimization: Squared values (z_re^2 and z_im^2) are cached to avoid redundant calculations.

Parameters

vars	Pointer to the structure holding rendering variables (e.g., z and iterations). @params data Pointer to the main fractal data, including the Julia constant (c).

Definition at line 84 of file julia.c.

{
    double  temp_z_re;
 
    vars->iterations = 0;
    while (vars->z_squared[COMPLEX_RE] + vars->z_squared[COMPLEX_IM] <= 4.0 && \
            vars->iterations < MAX_ITERATIONS)
    {
        temp_z_re = vars->z_squared[COMPLEX_RE];
        temp_z_re -= vars->z_squared[COMPLEX_IM];
        temp_z_re += data->c[COMPLEX_RE];
        vars->z[COMPLEX_IM] = 2.0 * vars->z[COMPLEX_RE] * \
            vars->z[COMPLEX_IM] + data->c[COMPLEX_IM];
        vars->z[COMPLEX_RE] = temp_z_re;
        vars->z_squared[COMPLEX_RE] = vars->z[COMPLEX_RE] * vars->z[COMPLEX_RE];
        vars->z_squared[COMPLEX_IM] = vars->z[COMPLEX_IM] * vars->z[COMPLEX_IM];
        vars->iterations++;
    }
}

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render_julia()

void render_julia

(

t_data *

data

)

Renders the Julia set fractal.

Renders the Julia fractal.

This function handles the full rendering process for the Julia set by iterating through all rows of the screen, rendering each row sequentially.

• Setup:
  • Calculates the scaling and starting coordinates based on the zoom level and positional offsets provided by the user.
• Row-by-Row Rendering:
  • For each row on the screen (y coordinate), the corresponding imaginary coordinate is computed.
  • The row is passed to render_julia_row, which handles the pixel-by-pixel rendering.
• Full Image Construction:
  • The ffunction processes every row until the entire fractal is rendered.

Parameters

data	Pointer to the main fractal data structure, including rendering details such as zoom, offsets, and fractal paarameters.

Definition at line 165 of file julia.c.

{
    t_render_vars   vars;
    int             y;
 
    calculate_scales_and_limits(&vars, data);
    y = 0;
    while (y < HEIGHT)
    {
        vars.c_im = vars.start[COMPLEX_IM] + y * vars.scale[SCALE_Y];
        render_julia_row(&vars, data, y++);
    }
}

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render_julia_row()

static void render_julia_row ( t_render_vars *  vars, t_data *  data, int  y  )

static

Renders a single row of the Julia set.

This function processes one row of the pixel in the Juliaa set by iterating through each pixel, applying the Juliaa set formula, and determining its color.

• Coordinate Mapping:
  • Each pixel is mapped to a complex number (z) based on its position and the scaling factors calculated from the zoom and offsets.
• Iteration and Coloring:
  • The Julia set formula is applied iteratively for each pixel.
  • The number of iterations is used to calculate the pixel's color.
• Row Processing: Each pixel in the row is processed sequentially, and the result is stored in the image buffer.

Parameters

vars	Pointer to the rendering variables structure (e.g., pixel and scaling).
data	Pointer to the main fractal data.
y	The current row index being processed (0 for the first row, up to HEIGHT - 1).

Definition at line 126 of file julia.c.

{
    int x;
 
    x = 0;
    while (x < WIDTH)
    {
        vars->c_re[0] = vars->start[COMPLEX_RE] + x * vars->scale[SCALE_X];
        vars->z[COMPLEX_RE] = vars->c_re[0];
        vars->z[COMPLEX_IM] = vars->c_im;
        vars->z_squared[COMPLEX_RE] = vars->z[COMPLEX_RE] * vars->z[COMPLEX_RE];
        vars->z_squared[COMPLEX_IM] = vars->z[COMPLEX_IM] * vars->z[COMPLEX_IM];
        julia_iterations(vars, data);
        vars->row = vars->pixels + y * WIDTH + x;
        *vars->row = calculate_color(vars->iterations);
        x++;
    }
}

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