Good health meter Tutorial

[bat78]

Let's make together a hi-tech health meter as for some sort of a space ship game.

• Create new canvas actor and drag its edges to make it thin and long.
  

  

  
  
• Yet, create another regular actor "gui_meter" and add it some futuristic animation. This will be one of our decorations for the health meter that will be centered.
  I'll be using this.
  
• Optionally, create one more decorative GUI actor for the outer design (borders). This is mine.
  
• You'd also like to set it as a view's child.
  
• Now create a local variable called "percentage" type "Real"
  

  

  
  So we can have a percentage of health for each actor we create. Isn't that a bit realistic? Theoretically everything has a health xD
  
• Now navigate to global code and put this:
  

  Code: Select all

  void set_health (Actor myactor, float value)
{
    float p = value;
 
    if(p > 99.0) p = 100.0;
    if(p < 1.0) p = 0.0;
 
    myactor.percentage = p;
}

void update_health_meter (Actor myactor)
{
    int i;
    double fraction = myactor.percentage * width / 100.0;
 
    // Background texture of the healthmeter
    for(i = 0; i < width; i += 2)
    {
        // Initializing our health gradient
        setpen(0, 0, 64, 0, 1);
 
        // Drawing our health gradient
        moveto(i, 0);
        lineto(i, height);
    }
 
    // Drawing health according to the fraction, skipping each 2nd pixel
    for(i = 0; i < fraction; i += 2)
    {
        // Initializing our health gradient
        setpen(255 - i, i * 2, 0, 0, 1);
 
        // Drawing our health gradient
        moveto(i, 0);
        lineto(i, height);
    }
 
    // Drawing our hybrid-alike decoration at the center of the healthmeter (OPTIONAL)
    //draw_from(gui_meter.name, width / 2, (height / 2) + 35, 1);
}

  
  Note that it is not intended to be much fps-wise.

Now when something happen for instance the player gets in collision with an explosion, simply do that:

Code: Select all

myplayer.percentage -= 10;

To decrease 10% HP of myplayer's initial health.
and along that, update the health meter with

Code: Select all

update_health_meter(myplayer);

To save unneeded FPS consumption create one global variable "myplayer_suffers"
assign 1 to it when player gets injured and do that in the health meter's draw actor:

Code: Select all

if(myplayer_suffers)
{
    myplayer_suffers = 0;
    update_health_meter(myplayer);
}

health_meter_example.zip

(222.99 KiB) Downloaded 595 times

In the demo you can also decrease HP with down/up arrow key.

[koala]

Neat.

Game Editor is very powerful tool when you know how to use C in it.

[bat78]

Neat.

Game Editor is very powerful tool when you know how to use C in it.

Yes, add me in skype: psp-gen I would like to know how much C do you know.

[Turon]

very nice little healthbar system , say, which part of the code effects the color of the bar? also I haven't gotten the enemy to kill the player yet ...

[bat78]

very nice little healthbar system , say, which part of the code effects the color of the bar? also I haven't gotten the enemy to kill the player yet ...

// Initializing our health gradient
setpen(255 - i, i * 2, 0, 0, 1);

[Turon]

I've never worked with local variables before, how are they different to normal user variables?

[bat78]

I've never worked with local variables before, how are they different to normal user variables?

There is no standardized notion such as "normal user variables".

In Game-Editor there are 3 types of variables in regard to linkage

• Global Variables
  Visible to every scope and actor. (global scope)
  Runtime extend (permanent lifetime / duration)
  External static linkage
  They are stored in "data" memory segment. Program's runtime memory.
• Local Variables
  Visible only to their block / scope { scope } (local scope)
  Scope-limited extend (unless declared with the static storage-class modifier keyword)
  Internal lexical/dynamic linkage.
  They are stored in the "stack" / "automatic storage class" memory segment.
• Actor Variables
  Those declared from the Game-Editor Variable Declaration Pane VDP.
  Visible to every scope and actor. Accessed through Actor.
  Runtime extend
  External static linkage
  I don't know where gE stores them, probably in "heap"

[Turon]

So global variables are different to actor variables in that they are stored data a memory segment as apposed to a "heap". but function exactly the same. So actor variables are declared through the script editor through the actor control?

[bat78]

So global variables are different to actor variables in that they are stored data a memory segment as apposed to a "heap". but function exactly the same. So actor variables are declared through the script editor through the actor control?

No I specifically wrote Game-Editor's Variable Declaration Pane.
Script Editor -> Variables -> Add..

Once you create a variable there it becomes an Actor variable. Which means a member of an Actor structure. Just like x, y, xvelocity, animpos....

[Turon]

Yes, GE's variable declaration pane accessable from the script editor. Thanks, I now have a better understanding.