Triggers in Action

hi, after i finished to update my system (installing and updating few things) i remembered that i said i will put some video to show triggers in action so i created a small map with a box attached to ceiling with few physics objects inside, so when i touch the trigger the box will be opened and the objects will fall down.
this is very simple example of using trigger_once (which trigger his targets only once), other triggers could be use at the same manner to achieve more complex behavior.

using triggers

if you have any question feel free to ask http://orenk2k.forumotion.net/

Doing some maintenance

hi, this week i did some maintenance, something i want to do for a long time is to replace my hard disk, my current hdisk (old 80 gb) start to do some noises so i thought its time to replace it, so i buy new 320 gb and clone everything.
i thought i will be fast and simple but the new norton ghost is so bad, i just want to do simple task (as i did in the dos days) and they make it so hard, they change the option for cloning hdisk to copy hard drive option which allows you to clone only one partition at a time and not the whole hdisk as one unit.
so i searched for another app, and i found really good software 'Acronis True Image Home', this is the best app i found for doing the job, very easy to use and have a lot of options to backup things. anyway i use it and it work perfectly.
i also install source control software (which i didn't use until now), the project become very big with a lot of files and it become very complicate to control it, so i installed svn (which i also use it at work), i really like this software, very fast and relaible.
the last thing i did is to upgrade my dev system to vs2008, i was using vs2003 which wasn't so great, i hope the new one will perform much better :)
thats it for now, bye

Triggers

hi, long time i didn't post anything, i'v been busy at work and also wanted to try few techniques and to read few articles from gpu gems 3 and gpg 7, i'm going to get a new copy of ai game programming wisdom 4 which will complete my series so i'm really looking forward to read it.
anyway, after checking some new methods on the graphics side (deferred methods) i wanted to get on with the gameplay so i decided to add new triggers to support interesting level design stuff.
background on triggers for those who are not familiar with it.
trigger is a convex volume which triggers an event when game entity (player, bots, projectiles etc) touches it.
simple example for using triggers: you place a door and want it to be opened only if you get nearer, so you place a trigger around the door but make it a little bit bigger so you will touch the trigger before you touch the door, you set the target of the trigger to be the door so when you touch it it will send a 'trigger' message to the door.
each trigger have basic attributes:
1) target - name of the entity that will be triggered when we touch the trigger, we can set multiple targets.
2) message - message to desplay when triggered
3) delay - amount of time between the touching and the actual triggering
there are few more relative to trigger type.
the triggers i'v added so far:
1) trigger_once - triggers only once, when it is triggered you can't trigger it again, can be used to destroy a bridge after you pass on it.
2) trigger_multiple - triggers multiple times, you can set wait time before the trigger will be trigger again when touched.
3) trigger_hurt - apply damage when touched, can set damage amount.
thats the main idea of triggers, i'v few more to add and there is cool stuff you can make with them.
next time i hope i will finish the rest and upload some video to show some action.
bye
as always if you have any question feel free to ask http://orenk2k.forumotion.net/

Custom Deformation

hi, quick update about new feature i'v added into material system called custom deform.
this feature allow you to create specific deformation on a geometry batch.
by saying specific i mean that you define 3 functions/expressions (anything you want), to define the deformation on x,y,z component of each vertex in the batch.
for example:
here is a material definition for sin wave deformation:
materialTestDeform
{
deform custom 0, sin(time+VertexIndex), 0
}
ok, what this simple material does to any geometry using it, is applying a sin wave deformation on each vertex on the y component. (the x,z component doesn't do anything as its 0)
time - internal keyword returning game time in ms
VertexIndex - internal keyword returning current vertex index of the vertex we are going to deform.
i could also use it to do some old scholl water deformation (using height map) by doing something like this:
materialWaterDeform
{
deform custom 0, heightMapTexture[256*VertexPos.y+256*VertexPos.x], 0
}
heightMapTexture - is the dynamic 256x256 height map texture
VertexPos.x/y/z - internal keyword returning current vertex component of the vertex we are going to deform.
this is just a few examples of using this new feature (you probably wont apply this water deformation as its not fast enough and could be done faster using the gpu)
because this deformation is based on the functions you define (its not constant), this could not be done in the gpu so its take some cpu time.
thats all for now.
if you have any question feel free to ask http://orenk2k.forumotion.net/

Forum For All

hi
i decided to open a forum to discus my engine programming and game development in general.
the main idea of the forum is to be the place to ask questions and hopefully get answers :)
it also contain game design area which allow you to share you work and show what you got, the main idea of this section is to get in contact with some talented users who would like to help with new models, animations, level design etc.
i still post news here but if you have any questions about something (new or old), i would like you to ask it in the forum, so enjoy and cya in the forum :)
forum address:
http://orenk2k.forumotion.net/

Improving Shadows System Continued

hi, last post i let you think on answer to some question about shadow updating scheme.
in short, the problem was that if dynamic entity gets into influence area of the light it means the light needs to update his shadow map, but this turns to be very intensive if this area contains lots of detail models which is static (read the last post to get the details and comments...)
ok, so the solution to this problem could be one of:
(1) two shadow maps for each light
(2) stay with one shadow map per light but...
(3) other
lets check those options:
(1) two shadow maps for each lights is the way to go but still raise some problems:
a. more memory (twice), if the light taken 1.5 mb per cube shadow map, now it will take 3mb!,
not so good as the reason i use shadow cache system is to maximize shadows cound and minimize the memory used by them.
b. we need to merge those shadow maps to get final one so we could use it when rendering, so we need another shadow maps for this! still the merging process isn't for free so i think you get the idea way this option isn't so good.
(2) here i stay with one shadow map per light but i use another shadow map which will be shared for all lights, this second shadow map will only used for dynamic geometry, so the unique shadow map per light stay ONLY for static geometry and the shared one ONLY for dynamic geometry.
so the memory issue solved, what about the merging? well, instead of merging those shadow maps in cpu, we merge them on gpu.
sound good but that means we need another shadow map right? not necessity, what i do is binding those shadow maps and merge them inside ps, and then i compute shadow map as usual. so instead of using the value sampled from one shadow map, i use the merged sample.
this method saved the need for another shadow map and the extra pass for merging them.
(3) other? nothing i see now, but maybe you could think of something?...
in practice its work very well and the performance gain is huge.
here is two screenshots show the results using this method:

using both static & dynamic shadows

using only static shadows

i see those screenshots but what is so special about them? its just shadow maps...
well yes and no, the first screenshot shows simple scene with few static geometry and one dynamic pickup item (armor), the only shadow map that is being updated is the dynamic shadow map, so what you see is the result of merging two shadow maps in the ps, so you can see both static and dynamic shadows.
the second screenshot shows the same scene but this time we picked up this item, so the resulting shadow map taken only from the static shadow map (dynamic one is empty!)

Improving Shadows System

hi
recently i'm working on performance issues and such, one of the biggest challenge in this area is shadows and how do we make them faster?
the answer to this question is another question:
how much cpu and memory can we sacrifice for this?
the answer to this one is: it depends on other process in the game and your platform.
so here i'm working on pc platform where memory is not an issue (like in ps2/xbox/ps3) so the main question is:
what do you do if you have big scene with 5000 point lights that need to cast dynamic shadows?
lets say we can determine their visibility very fast, so the bottleneck is the shadows generation and not the visibility of the lights. another assumption is that the lights is mostly static but if at any time we want some of the lights become dynamic, we could.
so the answer to this question can be one of those:
1. use light maps
2. compute all shadow map at load time
3. other
well, lets check those methods one by one:
1. light maps is out of the question because they are static and if a light is moving, his shadows wont be updated. also if we have a bridge and we walk beneath, the shadows of the bridge wont cast on our character, because when we compute those light maps, our character wasn't there.
2. this sound promising, it solved the problems in 1 but has another problem.
each point light using cube map for his shadow maps, that means 6 maps for each side, so if we take for example 256 by 256 cube map for all the lights we get something like 1.5 mb per light (assuming 4 bytes per pixel), this become 1.5*5000=7500 mb!! = 7.5 gigs, this is huge and of course cant be done in the real world when we have limited memory.
3. so what we need is a solution that solve both 1 and 2 and take reasonable memory, so the solution i come with is to use a cache system for shadows.
this system will have specific amount of memory dedicated to shadows and based on priority value we computed for each light the system will give cache entry for the most important lights (that is for example: the lights with large range and closer to the viewer).
so basically the system work with x entries that keeps shadow maps and set them as needed to the right lights, when we set shadow entry, we flag the light that he needs to update his shadows, this way we wont spend memory for far lights the viewer wont even see.
so when the scene loaded, the system set shadow entries for the most important lights and when the light tries to generate his shadows we check:
a. is this light have shadow entry? if not it means this light is not important and wont generate shadows.
b. is this light already updated his shadows or not? if not it means the light become dirty or someone flag the light that he need to update shadows (see below)
if we have shadow entry and the light needs to update his shadows, we get the shadow maps from cache entry and generate shadow maps for shadow maps stored in this entry.
when we done, we flag this light that he update his shadows so next frame we wont update it again.
few thing we need to consider:
1. if entity that cast shadows get inside light bounds, the light must update his shadows so the shadows of the entity will get in.
2. if the light is moving we need to update his shadows maps.
ok, so this is the main idea of the system and it is very fast and generic and as any algorithm, this have some tiny things that need to be done correctly so it works smoothly and handle all the special cases.
before i finish, here is another question:
what if we have a room with 500,000 faces with one point light that cast shadows?
we use this great shadows cache system :)
right, but what if an entity, lets say a small ball with 16 faces get inside that room?
hmm, the light need to update his shadows so the shadows of the entity will get in.
well, thats right but that means that for this tiny entity with only 16 faces you need to generate shadows from 500,000+16 faces???
think about it until next time...