A side-scrolling tactical 2D shooter that sets out to be challenging and to some extent realistic. The goal is to resolve situations where armed suspects and hostages are involved -- with as little bloodshed as possible. Inspiration is taken from the Police Quest and Rainbow Six series, while I add my own touch of blood and gore.

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Blog RSS Feed Report abuse Latest News: In-depth: Blood particles

6 comments by isbeorn on Nov 9th, 2013

So I thought I should write a bit more in-depth about features in my game and engine to give you some more content between the demo releases.

The characters, or bodies as they are named in my code have a number of properties that define their health and to emulate functions of the human body. Mostly in terms of emitting blood:

* Heart rate
* Blood pressure
* Amount of blood
* Number and size of wounds

The body as a whole has a blood pressure. This is simply the ratio of blood left in the body out of how much was in it from the beginning. It will be between 0 and 1 and it drops when the bodies bleed. It is combined with the body's heart rate so that the pressure changes in rythm with the beats. But the blood pressure value is not ready to be used at this point. Next it is passed on to the limbs of the body.

Each body has a set of limbs and each of these has an individual constant or modifier for the blood pressure. They are a bit different. For example the head has a much higher pressure than the feet. I'm no expert on these things but it's meant to be an abstraction of the different pressures in veins and arteries inside the body. The body's pressure is modified by this constant to create a local blood pressure for each limb.

Now on to the wounds. The limbs can have wounds (read bullet holes). These emit blood particles at a rate determined by the limb's local pressure. A wound at a limb with high pressure will squirt out the blood, while at lower pressure it will just drip. Remember that the pressure at the body level is based on the amount of blood left in the body. This means that each wound on the body decreases the blood pressure. In effect, this means that a single wound in the head of a body will pump out more forcefully than two wounds, or if there were many other wounds present on the body already. The size of the wounds also have an effect on how the blood will be emitted.

Low pressure due to loss of blood.

A smaller hole makes the emission more focused and the particles leave with a higher velocity. The size of an entry wound is determined by the diameter of the bullet. The size of the exit hole is more complicated and might be an article by itself.


A single emitter from the head with high pressure. The second one also showing pooling on the floor, and towards the end how the pressure is noticeably dropping.

Each emitted particle represents one milliliter of blood as it stands now, for a total of 4000-5000 milliliters (about one gallon) in a body's total capacity. Every particle has it's own velocity and is affected by gravity. When they spawn they also inherit the velocity of the limb they come from. You can see this in the gif above: when the head flips forward it makes a small bounce which is also makes the blood spawned at that time fly higher.

I hope you enjoyed this article. I will try to drop one once in a while when I feel there might be need for a 'filler episode' between my other updates.

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Demo 3

Demo 3

Jul 5, 2013 Demo 30 comments

The third Blood and Bullet demo adds more game play mechanics. Use concussion grenades to overwhelm the suspects. Restrain them, secure their weapons...

Demo 2

Demo 2

Apr 19, 2013 Demo 2 comments

This demo is more of a taste of game play than the previous one, but still with some obvious parts missing. There are more weapons, a bit of AI, rooms...

Sandbox/tech demo

Sandbox/tech demo

Mar 15, 2013 Demo 4 comments

This is not a game-play demo. I just want to point that out. It's a sandbox/tech demo of the features so far. It's scaled down a bit to keep it simple...

Post comment Comments  (0 - 10 of 194)
UltimateHeron Mar 26 2014, 1:11am says:

Oh,c'mon! Its been 3 months since you announced that demo 4. Release it as it is at the moment, please. Even, if its not working, or something.
I'm checking availability every day, like a month already.
And we all know, how hard it is to develop it by yourself only.
Just hear me please.

+1 vote     reply to comment
isbeorn Mar 29 2014, 9:56am replied:

I hear you. I feel that I'm disappointing a lot of you. It has ground to a halt and the explanation is simply that I'm doing other stuff. Those who have followed me know that it's happened before... This game is one of my hobbies, and there are periods where I just lose my motivation and spend time on my other stuff. It's unfortunate that I make promises and then lose motivation. :/ There will be more updates and a new demo to come but again I can't say when. It's in the nature of how I run this project.

+1 vote     reply to comment
UltimateHeron Mar 31 2014, 3:37pm replied:

Sure, its understandable. The most part of the situation you explained before. However, you should keep in mind, what we are with you and we maintain you everytime and everywhere. I wish you lot of inspiration. Good luck!

+3 votes     reply to comment
Cantalouper Mar 31 2014, 7:57pm replied:

We support you all the way. I think the community expected a demo 4, but it's nice to know you still care.

+2 votes     reply to comment
isbeorn Apr 1 2014, 3:21am replied:

Thank you both, UltimateHeron, Cantalouper, you really are the best support :)

+1 vote     reply to comment
Guest Mar 19 2014, 1:29pm says:

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SirMrPoopington Mar 1 2014, 6:22pm says:

Oh damn. Real AI! Awesome!

+1 vote     reply to comment
isbeorn Mar 1 2014, 3:24am replied:

I'm sorry. Life happened and I had to do other stuff the first weekend and now I'm sick :/

+1 vote     reply to comment
Cantalouper Mar 23 2014, 9:53pm replied:

You still alive?

+1 vote     reply to comment
gamer77 Mar 1 2014, 3:36am replied:

I wish a speedy recovery.

+1 vote     reply to comment
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Blood & Bullet
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Tactical Shooter
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Latest tweets from @bloodandbullet

Got solid grounds for animation driven locomotion in place now. Soon the characters will walk around and change directions!

Feb 8 2014, 6:57am

I've made some great progress on the new animation system. It feels solid.

Jan 19 2014, 9:21am

Planning and writing the new Body class. The new animation system will allow characters to turn in either direction and walk around.

Jan 18 2014, 8:56am

Now adding an audio browser to the weapon editor.

Oct 27 2013, 4:02am

I have a title screen background in the workings. I should add a main menu soon. The weapon editor now also imports properly.

Oct 20 2013, 3:32pm

The weapon editor is functional now! Just some minor things remain, then I hope to get some weapons produced for the next demo.

Oct 14 2013, 4:08pm

I made lots of progress on the GUI and weapon editor this weekend. The weapon editor is very close to finished now.

Oct 13 2013, 4:13pm

Had a good run with the new GUI system tonight. Not far away from bringing it into the weapon editor now.

Oct 2 2013, 4:00pm

The weapon editor is more work than I anticipated but it's progressing nicely.

Aug 4 2013, 7:23am

Striving to get the weapon editor done today.

Aug 3 2013, 3:44am

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