Thursday Back To School

Orthographical Thoughts

I spent a good five hours last night researching all manner of shadow mapping techniques, and from my initial query of Cascade Shadows I finally rested on the technique called Parallel Split Shadow Mapping (PSSM).  Countless white papers, plenty of anecdotal evidence, many blogs, few demos and even less source code.

During my time I learned a whole heap about the horrors that can strike at a typical shadow mapping render.  Self shadowing issues, filtering issues, performance and memory considerations, compatibility, the list literally goes on and on.

After trying to dig out running examples from the InterWeb I finally found the ideal example sitting on my own PC inside the June 2010 SDK called CascadeShadowMapping11.  Sure it's DirectX 11, but I am familiar with the SDK and the HLSL variant and was able to trace through what was going on.

I then started augmenting my prototype to include the technique, but soon came to a full stop about 2PM today. Here is where I got to:

Coding the technique from the DBP and Shader code was fine, but two reasons brought me to a halt. Firstly, I ran out of commands, such as producing an offset orthographic matrix and producing a depth only camera.  Secondly, I realised that I did not want to create a huge amount of cameras to achieve the effect as at some point it had to integrate nicely into the main engine which has many cameras spoken for.

Changing Gears

Given the above situation, I have decided to switch away from the DBP side and dive directly into the DLL side.  That is, write the entire chunk of code responsible for shadow mapping inside the DLL so I can write it in pure C++. Not only will the results be faster, it will be easier to debug and trace though and I will be able to cut and paste some code from the DirectX SDK example to speed up my implementation of the various elements required to achieve great outdoor shadows.

I will bear in mind that the same code will be used for dynamic omni-directional point light shadows, but I think we will all agree that the first major milestone is to have a nice outdoor scene with great shadows cast from the sun that treats every object as both caster and receiver.

Signing Off

It will be exciting to see this up and running, but now I have to dive deeply into some old school DirectX 9 coding.  Time to refresh my knowledge about how to create render targets, perform 3D math and talk to my shaders.  The good part about this approach is that when I next run the map editor, all I need to do is replace a shader then 'switch the sun shadows on' :)

Wednesday In Shadow

Cloud Bound

I was planned a trip outside today but the clouds and rain conspired to keep me inside, and perhaps it was for the best.  I spent the morning reading up on various shadow mapping techniques as a refresher, then looked at some of the excellent world Evolved had done in DBP, and with a little rolling up of sleeves managed to create a prototype shader which employs cone based parallax rendering (thanks to Mark B) and shadow mapping (thanks to Evolved).  Here is an early video, which I sneaked past Rick, our QA guy:

As this is a first attempt there are some artefacts here and there, but I am happy that the technique is not too complicated to wrap my head around. I need my head clear for more challenges tasks that lie ahead.

Segment Art is hot on the heals of this coding work, so expect the video quality to jump up in the next few weeks :)

Evening Plan

It's late afternoon now and I'm quite buzzed at the prototype and just keep running it and wondering around. Once the buzz fades, my next task is to introduce an adaptation called Cascade Shadow Maps.  The premise is that instead of one all powerful texture holding the shadow for the entire world, I actually have four, with the first providing shadow for the entire world and the virtual camera sitting somewhere in orbit, while the forth shadow texture will be right up close to the centre of the player's head where we can produce much more detailed shadows that bears close scrutiny.  Of course all this produces a single global shadow, but it will be a great addition and absolutely necessary for outdoor scenes.

Brain Bursting Idea

In contemplating how best to handle point lights indoors, I hit upon a rather nice compromise which will allow hundreds of point lights but not drain the performance.  The performance drain comes from the fact that the typical omnidirectional shadow casting technique requires me to render outward from the light source in six different directions, every render cycle, to create dynamic shadows from a single point light. Multiply that by even a few lights and you are looking at screen shots, not refresh rates.

My plan is elegant in it's simplicity, which is to switch off the updates to these point light renders, but keep them in storage.  This way I can use the last known shadow render depth details when rendering the final lighting scene.  Only when an object passes by one side of the point light to I need to update, and only when the whole light moves do I need to update them all. Imagine them as real-time lightmapping textures that can instantly reflect changes in the scene, but when not updated are as fast as baked lights.  Neat or what!  Again, all theory, but will be a very cool way to solve the issue of many lights in a confined indoor scene that needs to cast many shadows.

For all the techniques I can research and dream up, it will always come down to performance and I am slowly coming to the concious conclusion that Reloaded should be targeted at next gen hardware. Gamers expect these advanced visual techniques, and who knows how long it will be before baked lights are a think of the past. Best to future proof Reloaded now while we're developing it, and leave that door open to lots of additional techniques that may rely on cube based shadow targets and deferred rendering methods.

Signing Off

It has been a day free of bugs, and much progress, so I could stop now and call today a roaring success.  Problem is, I am having too much fun, so with basic shadow mapping under my belt, time to try out a little cascading!

Tuesday Diary

And Then We Had Blessed Cloud

Another fine day in developer land, and the sun has finally retreated behind the cool embrace of Welsh cloud. That means my office is no longer a sauna, and like a Troll, my brain is starting to function again in the cooler air.

I have my little task list for today which comprises mainly of dealing with the last of the map editor fixes. I have knocked my emails on the head this morning so my afternoon is free to code and conceptualise to my hearts content.

Running the current version was quite a good feeling as for the first time in weeks and weeks I can pick a segment, and paint with it without horrors appearing on the screen. 

An Art Treat

After days of art-less blogging, I can reveal some new art to you in the form of some animations I left would help the final Reloaded game play experience.  Rather than read my whittering, here is Mark to present the extras in this very cool video:

I am particularly excited about the pointing 'while talking' animation as it really opens up a whole new series of features for NPC and Combat interaction. Imagine hiding from a group of enemies, and in the distance you have your zoom lens locked onto the group commander. You see him talk with his men, then suddenly point in your direction, ooh the chills.  I must maintain composure each time I see these animations as I know deep down it's the AI and game play that will make or break Reloaded. My current tasks are akin to rebuilding a straight six engine, when the exciting part are the lines of the car and the toys inside!

Remaining Issues

Off the bat I can see the editing does not delete at low LOD, which will need some more data structures and code to support this. The highlighter flickers which indicates which segment is being edited, there is some Z clash on the floor when you paint floor segments down, when you paint quickly, there is a performance hit as the deletion code rapidly removes (or to be added again) segments which is noticeable on my monster rig. That means it will definitely show up on an average machine.

Not sure what order I will tackle these issues, but a nice cup of tea will certainly help the decision making process.

13:45 A Cup Of Tea Later

I have decided to skip optimising the deletion code and leave it slowish for now, so I can focus on adding the required functionality for the map editor. I will doubtless see opportunities for speeding things up as I go along.  I have also fixed the highlighting and Z clash issues, so my primary task now is editing in the low LOD areas (which in theory is just an extension of the high LOD deletion system).

14:42 Quick Tip

A nice tip for the new coder. When you are amending a data structure to include new fields or additional dimensions to an array, add the extras to the data structure and all the code that used the former structure, but don't add any new functionality associated with the new additions. Get your app working as before so you know existing functionality is in tact before expanding your code and using the new fields and data for the intended purpose.  This way you are only fighting one fire at a time :)

14:56 Low LOD Deletion Done

Using my super tip, I was able to step through the logical steps to increase the capabilities of the delete code to include the larger low LOD area, and now I can paint and delete at any level of editing, which is great!

In testing this though, I found a new issue which was that when you overlay two segments on top of each other (which is fine), when it comes time to delete the crossed segments, they stay there. It gets worse, as in another test when I drew a segment over another one, two more segments that neighbour them also refused to delete.  Just like bubbles, you push one down and another pops right back up :)

15:18 LOD Transition fixed

Before I could solve the above, I noticed the LOD transition was off on segments in the positive directions, now fixed and it's great to see an almost perfect transition in LOD right up until the camera clipping plane eats them. Something we never had in FPSC classic so a great addition!

15:29 Multiple Deletions Are Go

I disabled the code which only deletes segments of the same type and now we have no left-over segments, hurray!  If I don't probe too deeply, I can be quite happy with how the map editor now behaves with the new instance stamp implementation.  It does not do segment overlays, entities, lights or anything else you might associate with the editor, but segment editing, memory handling, rendering and LOD are all working nicely.

15:48 Eye Candy

Earlier today I was interrupted by Rick with the request to have some 'decent' stuff to show in a few weeks time when I disappear for my two week vacation. I only have one 'test' segment, which really does not help me construct a detailed game shot :)  To this end I fired off an email to Mark to start the serious work around segments, scenes, shaders and all things beginning with S.  While I wait for that reply, I have decided to derail my current work to get the map editor 100% back to factory functionality, and instead switch over to 'fancy visuals' mode.

Before I mentally switched tracks (about ten minutes), I created a small scene (oh, you can't save and load levels either as the level constructor code still uses the old system) which was a very very long tunnel from one end of the level to the other. As I ran down it, I considered how great it would be to use a shader to demonstrate parallax rendering here, and also to experiment with other visual techniques for shadows, lighting and anything else we need for the final shader.

Signing Off

I just noticed how long this blog was getting, and I don't want to be accused of spending all my time blogging about Reloaded instead of coding it, so I will end here. The rest of the day and evening will be working on the new shader prototype, which will be designed to drop into the map editor and allow that wonderful shaded tunnel scene I described above.

Hopefully in the next two weeks you will see some nice eye candy and visuals to excite you about Reloaded. It's not the best time to pull away from the map editor functionality work (as it's fresh in my mind), but the shader work is also time critical as Mark needs these early results.  It will also be fun too!

Monday Progro

Good Editor Work

A good day of coding done and more of the map editor is now working nicely.  Multiple textured segments being drawn, modified and removed. Scrolled out of the visual area then scrolled back, and also LOD working when you pull out to view the whole scene or from first person view, in the distance.

In testing my new code creations, new issues did surface such as not being able to 'delete' in the low LOD regions which was deliberate. I assumed that editing would be done up close in high LOD areas, but I quickly saw myself zooming right out and then painting a monster huge room, which added fine but I could not delete it with the same art tool.  Something for Tuesday's list.

The Long Road

I would probably have done much more code today where it not for a curious detail of everyday development. The actual code changes to fix the above could be done in a few minutes given a super-human brain, but regular humans take a little longer. The issue was not fixing the code, but finding which code was responsible for erroneous data. When that erroneous data is buried deep deep inside a data structure system that needs five minutes of software usage before the issue emerges you find it almost impossible to even remember what you where originally looking for.

To help me on this quest, I used my handy notebook to sketch out a map of all the data as it was being created, so that I could stay oriented as I mined through nests upon nests of indirect data.  Fortunately, persistence and a pen paid off and I was able to enjoy a hassle from map editing experience as the clock tolled 6PM.

Hopefully segment art will appear in the next two weeks which means you will start to see some nice videos of all this boring Technic stuff ;)  Rick is positively leaping up and down for the visual side of things to mature so for those waiting for the eye candy, you have a champion on the inside working for you.

Signing Off

I clocked another two hours this evening to bash down the emails, write this blog, and sort out my wish list for Tuesday.  I did a little work on the shader for the current SAND segment which is the ONLY Reloaded asset for map editing right now. This is in preparation for dropping in a better shader from the new prototype which will eventually furnish the goodies.  Not only will I be exploring deferred rendering in this prototype, but working with Mark to conjure a shader that gives us a great universal set of visual attributes that the whole scene, both static and dynamic can utilise.  Unlike FPSC Classic, we want Reloaded to feel like every pixel belongs in the same scene.

Weekend Deleteathon

A Day Of Deleting

As you may know the task this time is to finish the map editor editing system and then move swiftly onto some deferred rendering prototypes.  Alas.

I made good progress with improving the map deletion code, which was 94% searching and 6% fixing due to insane reproducibles.  One example would be use a large radius spray can to spray over an area of 100x100 grid tiles, then return to the initial corner and delete a few segments at random. The bug being that some will not delete. Now try reproducing that exactly so you can trace the hundred fold nests to see what the contents of arrays of floats buried behind double jump reference pointers. It's no picnic!

Some Good News

Even though deferred rendering is now a distant ambition for the weekend, it looks like I am very close to cracking the editor delete stuff and only have some low LOD issues to tackle (they don't go away when the high LOD is in play) and as the delete code only handles high LOD geometry, it makes it look like the tile was not deleted when in fact it's the low LOD I am now looking at.

To be fair though, adding and subtracting from buffers and a cascade of variations was always going to be a tricky one to test and refine, and when you mix in multiple overlapping buffers you know you're in for a world of pain. With a little luck, I can put these glitches on the fixed list and have a working editor come Monday.

Signing Off

Sorry no pictures today but everyone went home and left me with my programmer art hands. I have thrown out a few emails in order to get some content this week so watch this space for the graphical stuff :)  For more technical headaches and insights, join me on Monday for more lovely ranting!  Also, for the many new users who have subscribed to my YouTube channel, thanks muchly. I would ask though that you direct all your comment questions to the blog so I can answer everything in one place and have a single location for all answers Reloaded flavoured. Thanks again!

Friday mobilious

Lee is out at the moment

As promised here is my Friday blog. I am trying a blog from my phone to see what capabilities I have. It is not ideal as I cannot. control font and bold. Eek!

Signing off

Not my shortest bblog but I wanted to post that I will be coding Saturday so stay tuned!  The plan is to finish and fix the map editor delete functionality and play with some deferred protos.

Thursday Edits

Back In The Engine

Well my sunburn subsided and I was able to get some coding done. The task of the day was to get the system to handle multiple textures, not just the single texture mesh I was throwing at it so far.

A Maze Of Texture Complexity

Sounds easy enough you would think to add some texture goodness in there, but it turned out the whole system hinged on the fact a single buffer would be created to handle an area of the map. As it happens, for multiple textures to exist, multiple buffers where needed to be created that overlaps other buffers many times. Not so bad in terms of memory usage, but performance took a hit as more buffers where created on demand as new textures appeared, and also the draw call count increased as there are more buffers in the same scene space, each holding their specific texture.

In my prototype, this resulted in a very notification drop in frame rate when segments of 17 frames where stacked left, right and up in front of the viewer (worst case scenario). During the map editor tests, the performance hit was not noticeable as segments are drawn in much much fewer quantity, and the final result will only really be known when we start throwing real scenes at it. It is a necessary addition, and I hope it does not force me into too much distracting optimization work, but there are a few easy speed ups in there I am sure.

The good news is that it's in now, and I can paint segments of different textures, and segments that contain different textures inside them too. I did notice too that only the first segment permutation was drawn, which meant I could not add subsequent walls, floor, e.t.c. That lead me to my next piece of code.

Inter-Tile Editing

A feature of the new instance stamp system is that to change the scene, you must first remove the reference from the map and buffers, and then add a new instance of the object with any changes required such as limb visibility and rotation. A very instant task for sure, but when the tile is already filled it skipped the delete part.

After adding this new code, I could now add walls and floors like a trooper. The downside is that for some reason the delete code can occasionally target other polygons and remove them. I noticed this before, but now this new code is in it is much more reproducible.

My priority task Friday evening will be to find and fix this remaining issue and we will have a 'sort of' working map editor that allows different segments to be added, edited in place and removed from the 500x20x500 scene :)

Art News

No new art to show you today, but I can report that Mark's brain is now irrevocably set to segment art thinking mode, so expect juicy segment and scene art in the weeks to come. I can't wait!!

Signing Off

I have a busy road day Friday as my mail order department shifts 108 miles from Wales to Wigan for 2 weeks as my chief mail order dudette takes a well earned break, and my equally hard working Wigan dudette takes over. This will mean my morning and afternoon will be out of the office, but I plan to throw down a few hours that evening and spend a good part of Saturday chasing this code down too.  All in all, quite pleased with how the map editor is slowly being put back together.