Loop hook

Now that you’ve understood the basics of MacroLibX, we’ll start by drawing a little animation in the window. To do this, we’ll be using two new functions: mlx_loop and mlx_loop_hook.

Loops are a MacroLibX feature that allows you to keep calling your hook stored in mlx_loop_hook to render new frames, which you must, of course, transmit to the window yourself.

🔄 Hook an update function

To initiate a loop, we call the mlx_loop function with the mlx instance as only parameter, you should have seen it before :

#include "MacroLibX/includes/mlx.h"

int main(void)
{
    void* mlx = mlx_init();

    mlx_loop(mlx);

    mlx_destroy_display(mlx);
}

This will do nothing of course as we have no loop hook registered, therefore we will not be able to write anything to our frame. And without any event hook, this will just be an infinite loop :sadge:

To make our application more ‘dynamic’, we need to hook an update function to be able to change what’s rendered. An example of dynamic application could be :

#include "MacroLibX/includes/mlx.h"

// usefull struct
typedef struct
{
    void* mlx;
    void* win;
} mlx_t;

int update(void* param)
{
    static int i = 0;
    mlx_t* mlx = (mlx_t*)param;

    int color = 0;
    for(int j = 0; i < 400; j++)
    {
        mlx_pixel_put(mlx->mlx, mlx->win, j, j, 0xFFFF0000 + color);
        mlx_pixel_put(mlx->mlx, mlx->win, 399 - j, j, 0xFF0000FF);
        color += (color < 255);
    }
    if(++i == 5000)
    {
        // here the rendering changes, the red put pixels
        // we made in the main loop are erased
        mlx_clear_window(mlx->mlx, mlx->win);
    }
    return (0);
}

int main(void)
{
    mlx_t mlx;

    void* mlx.mlx = mlx_init();
    void* mlx.win = mlx_new_window(mlx, 400, 400, "Hello world!");

    for(int i = 0; i < 100; i++)
    {
        for(int j = 0; j < 100; j++)
        {
            // this will be rendered until we call `mlx_clear_window`
            mlx_pixel_put(mlx, win, i, j, 0xFFFF0000);
        }
    }

    mlx_loop_hook(mlx.mlx, update, &mlx);
    mlx_loop(mlx.mlx);

    mlx_destroy_window(mlx.mlx, mlx.win);
    mlx_destroy_display(mlx.mlx);
}