Author(s): 41


Permalink 11:31:37 pm, Categories: GSoC 2014  

State of shadows

While both renderer deferred and pssm works great but their shadows doesn't seems to be working as they should. If we load a scene with deferred renderer enabled, it appears that everything works fine


Until, you load point or spot light. Things begin to look weird.
When the light is close to the object it is casting shadow of things look fine.


However, if light move away from the object, there is no shadows


Same thing happens for point light.

Possible reason for this issue could be that the shadowmaps aren't rendered correctly but dump texture of shadowmap says otherwise.


Maybe its the hardware issue. I tried it on different hardware but still the issue persists.

Now the only possible reason for this issue to occur could be at the shader level.
shadow_depth.xml is responsible for mapping the shadows but nothing seems to be wrong there. Could be, the shader is taking slices into account which it shouldn't or coordinates from use_buffer.xml aren't sent right.

In addition to that pssm render manager is broken. It used to work earlier but now it doesn't exhibits shadows. weird!

Permalink 06:24:12 am, Categories: GSoC 2014  

Working with lights

There are several ways to enable lights in Crystal Space. One being from world file (XML). Following is the syntax to lit them in your environment.

1). Point light :-
<light name='Lamp'>
<center y='10' x='0' z='0'/>
<color blue='1.0' green='1.0' red='1.0'/>


2). Directional light :- Same as point. rotate the matrix to change it's direction
<light name='Lamp'>
<center y='10' x='0' z='0'/>
<color blue='1.0' green='1.0' red='1.0'/>


3). Spot light :- requires some additional values
<light name='Lamp'>
<center y='10.00' x='0' z='0'/>
<color blue='1.0' green='1.0' red='1.0'/>
<spotlightfalloff outer="50" />



Permalink 10:22:13 am, Categories: GSoC 2014  


Yet another GSoC, only this time its shadows.
Game on!

Permalink 10:00:33 am, Categories: GSoC 2012, GSoC 2013, General  

How water looks

And that's how the CS water looks.
Youtube Link!


Permalink 05:12:14 am, Categories: Weaver  

Shader Weaver


Shader weavers are intimidating at first mainly because it is difficult to debug them and connections are quite confusing.
The basic idea of weaver can be learned from here. However, the code written in it is outdated... better to go with code.

Following are some weaver debugging techniques that I learned.
1. Debugging by altering the output color. ex


2. CS flag to Disable shader cache : -cfgset=Video.ShaderManager.EnableShaderCache=false

3. CS flag to Dump shader program at %temp%\shader : -cfgfile=/config/shader-debug.cfg

4. Dump textures at %temp%\textures

   a. CS flag : -plugin=bugplug
   b. ctrl+d
   c. ctrl+shift+t

5. Switching between CG/GLSL

   a. simplest way is to delete the shader plugin that isn't needed.
   b. Disable GLSL only : 
   c. remove/edit the GLSL/CG technique in main entry weaver. 

6. CS flag to check syntax error: -verbose


Permalink 04:30:51 am, Categories: GSoC 2013  

Concluding GSoC 2013

Entire water's shader code has been ported to weaver which will enable to add post effects easily. Plus heightmaps to generate natural water waves and larger ocean size.
Now it looks like this...




Permalink 03:07:37 pm, Categories: GSoC 2013  

Update GSoC 2013

Howdy folks!,

So I had prepared couple of thing that had to be done before actually starting with interactivity.

1). Porting XmlShaders to ShaderWeaver.
2). Mismatching of texturemaps.
3). Large Size of Oceans
4). FFT in oceans
5). miscellaneous

As for 1). I tried to port the code, but I'm kinda still struggling to get it right. Thanks to res, Rlydontknow and Sueastside I'm able to understand them quite well but still weird errors priest.

The Mismatching actually didn't existed in temporary weaver code. so I guess the complete weavers should fix this issue.

The values of CELL_WID, CELL_LEN and MAX_OCEAN_DISTANCE are increased to spread the ocean even wider. but they increased the pre-computation of LODs thus the "gran" (vertex per tile) had to altered accordingly. gran = pow(2.0,LOD_type)/64.0f;

FFT needed VS texture mapping, but weavers weren't complete at the moment. So I decided to give it a shot in old shaders. If you look at the FFT implementation then you'll find that FFT is essentially creats a complex "texture". FFT calculations are very heavy. Thus it would rather be easier to just take a heightmap and use for ocean waves. It actually gives pretty decent result.


Along the way I found that the ocean water move along the camera which shouldn't happen because in a game water usually stays at one particular position. It does that due to LOD calculations. So along with taking waves parameters from the world file, the plugin will also take position and radius to which the user wants it to extend.



Permalink 08:04:16 pm, Categories: GSoC 2013  

GSoC 2013

This Summer is going to be really exciting. I'm gonna beat the heat by mutating the CS water system. Thanks to CS community for considering my proposal on water simulation. Watch out for Wet CS!
starting with shaders. ;)


Permalink 09:59:06 pm, Categories: GSoC 2012  

Ocean's Shoreline

Hey all,
So finally I finished with Shoreline implementation. I know my work should be over by now but I'm happy with new things i'm learning each day. :D. Basically I took a foam texture (programmers art like) and blended it on ocean mesh where ever ocean touches terrain.
This is done by first getting all the points( These points are in world space) where ocean touches terrain and then scale them down to store it in an array. Till now all steps are pre-computed on CPU. That array is now passed to shader program. Now in a vertex program, nearest distance between vexter position and array of foam points is computed and then that distance is passed to fragment program. In fragment program foam Colour is clamped depending on the distance.

Important note:-
I got pretty much everything working with ease except for first step i.e. Getting the foam point.
To get foam points first I got terrain from engine into the water plugin. Then iterated over each terrain cell's height map. Now the thing took me so long was that The coordnate system usually start from bottom left corner so are iteration over cells. But when you are performing texture(heightmap) lookups the coordnates start from top left corner. It took me 7 days to understand this.

This is how it looks like:-


Side notes:-
*Array size is limited to 1000 a better way would be to create a texture and store all those points in it and perform a texture lookup in shaders
*This shoreline only works for Terrains. In order for them to work for any mesh, a plan collider can be used to get foam points. Rest of the steps would remain the same.

-Naman Gupta


Permalink 12:09:30 pm, Categories: GSoC 2012  

Ocean Shaders

Ocean looked nice with connected meshes but it lacked reflection and refraction. Although Ocean is actually a deep water system thus should have no refraction but I did it anyways. For this implementation i followed this Paper.

It involved 5 basic steps.
1. Create the reflection texture : provided by engine
2. Create the refraction texture : provided by engine
3. Distort the textures according to a dudv-map :- We don't need it as it's used to apply distortion. Normal map worked equally great.
4. Apply bump mapping : not needed since we are using vertex shaders to generate waves.
5. Combine with fresnel effects : no problem :)

and here's the result

Ocean reflect refract

and this

island ocean

Some notes
-ocean exhibits No caustics. Caustics are already implemented in CS but aren't in ocean
-This shader is *not* shaderwaver. It is regular vertex and fragment program.
-LOD pops out as you move along.
-ocean doesn't entirely covers the island. a possible solution for it could be to increase the cell width and leght and corresponding parameters. so that it covers more area.
-also waves direction appears to be changing between different LOD when viewed from top. implementing inverse FFT could remove it, I think.

-Naman Gupta

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