Opacity based health system.

[Lightmind]

Basically, when my player takes damage, i want the health to go down from 100 to 90. Then, based on the health the player is at, i want the opacity of one heart to change. I've got 5 hearts, each representing 20 health. They are all in different objects. The first heart goes from 100 to 0 opacity from health 100-80. The second heart goes from 100 to 0 opacity from health 80-60 etc.

 

[Nidoking]

Sounds like a job for image_alpha, draw_set_alpha, or passing the appropriate alpha value to whatever you're using to draw the sprites.

 

[FoxyOfJungle]

You can always divide the current value by the maximum value, getting a value from 0 to 1, which will be the opacity. Do this for each heart.

 

[Lightmind]

The thing is, I don't actually know to do this cos im noob.

 

[chamaeleon]

Maybe something like

for (var i = 0; i < 5; i++) {
    var alpha = max(0, health_counter-20*i)/20;
    draw_sprite_ext(spr_heart, 0, x+64*i, y, 1, 1, 0, c_white, alpha);
}

Not very well tested. I might have made a mistake here or there with the math logic.

 

[EmperorHouse]

Tried to make it general and intuitive. Haven't tested it yet, but hopefully works.

var hearts = hearts_max*(health/health_max),   //num hearts filled
swid = sprite_get_width(spr_heart); //width of sprite
for(var alp, h = 0; h < hearts_max; h++){
    alp = min(hearts-h, 1.0);  //alpha 1 if below current hearts
    alp = max(hearts-h. 0.0); //alpha 0 if above current hearts
//alpha between 0 and 1 if less than 1 above current hearts
    draw_sprite_ext(spr_heart, 0, x+h*swid, y, 1, 1, 0, c_white, alp);
}

 

[chamaeleon]

    alp = min(hearts-h, 1.0);  //alpha 1 if below current hearts
    alp = max(hearts-h, 0.0); //alpha 0 if above current hearts

The second line overwrites the result of the first. Perhaps you want to use clamp().

alp = clamp(hearts-h, 0.0, 1.0);

which is equivalent to

alp = max(min(hearts-h, 1.0), 0.0);

or

alp = min(hearts-h, 1.0);
alp = max(alp, 0.0);

 

[EmperorHouse]

The second line overwrites the result of the first. Perhaps you want to use clamp().

alp = clamp(hearts-h, 0.0, 1.0);

which is equivalent to

alp = max(min(hearts-h, 1.0), 0.0);

or

alp = min(hearts-h, 1.0);
alp = max(alp, 0.0);

Haha, you're right. In my head I was thinking

alp = min(hears-h, 1.0);
alp = max(alp, 0.0);

Which does the same thing as using clamp, which I forgot existed.