The particle code is shaping up nicely. This is now the third re-design from the ground up and this is the one that I’m sticking with. I decided to use the CPU for particles. Yes, it is limiting and, yes I am aware of things like texture-data, transform feedback VBO, and OpenCL particle systems that run in parallel on the GPU. I chose to implement particles on the CPU because I wanted to have a modular system that was easily extensible. I didn’t want to write a tool that would dynamically generate a shader or OCL kernel for every possible combination of parameter manipulation modules. I wanted to have access to the particle data in order to do things like per-particle light sources and collision.

The current system meets these needs by using what I’m calling modules. Modules implement interfaces and are assigned to emitter definitions; essentially a form of dependency injection. Emitter definitions are collected within system definitions or assigned to other emitter definitions as child emitters that spawn either at the birth of a particle or on the death of a particle. Particles exist in an array and are generated on start-up. The particle pool manages particles by allowing emitters to request either a sorted or unsorted particle, and allows a maximum of 10k sorted and 20k unsorted particles.

When the particle manager receives a request to create a new particle system from a definition and attach it to the scene graph, it creates a new system instance, and subsequent emitter instances. The instance classes are very lightweight and contain instance specific members such as system world position, emitter position relative to the parent system, active particles, and counter modules copied from the definition. Each emitter contains a reference to it’s definition and, during the particle update loop, the modules attached to the definition are called and passed a particle to act upon.

Using a modular dependency injection in this way greatly reduces conditional branching within the update loop and allows new behavior models to be added quickly, easily, and with very little risk of breaking the save format.

Features:

• Position modules
• Velocity modules
• Acceleration modules
• Rotation modules
• Animated vector flow field based on Perlin noise
• Textures
• Billboard, +x facing, +y facing, +z facing
• Double sided with reversed texture on back
• Keyframe interpolation for color, alpha, size, texture index, rotation
• Burn parameter for smooth interpolation between alpha and additive blending
• Emissive parameter

Total Project Statistics:

---------------------------------------------------------------
Language     files          blank        comment           code
---------------------------------------------------------------
Java           645          15593           7098          45229
PHP            309          10275           5858          26722
CSS              6            641             68           3242
GLSL            62            458            130           1839
Javascript      14            262             89           1192
XML             11            158             16            771
HTML             3              8              0             42
DOS Batch        1              0              0              1
---------------------------------------------------------------
SUM:          1051          27395          13259          79038
---------------------------------------------------------------

Didn’t get much done this week with the holidays and all, so I’m afraid there will be no update this weekend. I did get a great start on the animator and I hope to release it in next weekend’s update. Stay tuned!

---------------------------------------------------------------
Language     files          blank        comment           code
---------------------------------------------------------------
Java           472          12499           5307          35440
PHP            309          10275           5858          26722
CSS              6            641             68           3242
GLSL            54            407            111           1579
Javascript      14            262             89           1192
XML             10            134             14            669
HTML             3              8              0             42
DOS Batch        1              0              0              1
---------------------------------------------------------------
SUM:           869          24226          11447          68887
---------------------------------------------------------------

Version 0.0.144e is live!

This week was spent adding features to the sprite editor and I’m proud to say it’s done and time to move on to the animation editor. Here are some screens and the changelog.

I have nightmares about Java layout code.

Launcher:
* Fixed Windows Aero graphical glitch

Sprite Editor:
+ Palette string tags
+ Improved selected swatch indicator
+ Widescreen view
+ Center pane now uses all available space
+ Procedural HSB palette variance
+ Improved color preview in swatch editor and swatch selector
+ Scroll wheel scrolls through slices when hovered over slice view
+ Selection tool with selection size and location modification
+ Cut / copy / paste selection
+ Undo / redo paste selection
+ Fill, paint, delete selection
+ Select all
+ Crop to selection
+ Resize sprite
+ Clear palette button
+ Symmetrical editing: paint, fill, add, erase and most selection edits
+ Hold A, W, or D and scroll to move selection in 3D view
+ Hold A, W, or D + LShift to size selection in 3D view
+ Copy / paste palette swatches
+ Luminosity value for each palette swatch
+ Luminosity preview mode in 3D view
+ Swatch edits and pastes can now be undone
+ Redo functionality
+ Grid and sprite bounds visualization in 3D view
+ Origin editing
* Fixed timer thread shutdown bug
* Fixed duplicate filename extension bug

---------------------------------------------------------------
Language     files          blank        comment           code
---------------------------------------------------------------
Java           413          11046           4183          30782
PHP            309          10275           5858          26722
CSS              6            641             68           3242
GLSL            54            407            111           1579
Javascript      14            262             89           1192
XML             10            134             14            669
HTML             3              8              0             42
DOS Batch        1              0              0              1
---------------------------------------------------------------
SUM:           810          22773          10323          64229
---------------------------------------------------------------

Sprite editor in progress… will be in the update this weekend!

I had to write a converter to be able to load in the old LSS sprite format. As you can see by the picture with the orange hair, the old format was somewhat wasteful. Also, I ran into a problem: the old format uses three floats per voxel to represent color whereas the new format uses 16 indexed colors. This means that the old format used way more than 16 colors.

When I first loaded the sprite with orange hair, I used a simple bit of code that just  put the first 16 unique colors into the swatches. All swatches were filled with various shades of orange. Not good.

So I thought about it a little bit. RGB values from 0.0f to 1.0f can be thought of as three dimensional points in the first (+, +, +) octant. Therefore it should be pretty straightforward to use the distance formula [ d = sqrt(deltaX^2 + deltaY^2 + deltaZ^2) ] as a measure of how similar two colors are. Testing against a threshold [ if d < threshold … ] allows subsequently discovered colors to use an existing indexed color if the new color is close enough.

It’s not perfect as it still produces some anomalous results, but it’s good enough to retrieve some of the hard work I put in on the old sprites a year ago.

Current features include:

• Saving / loading sprites
• Importing / exporting palettes
• Importing old LSS sprite format
• Slice bounds visualization in 3D view
• View only selected slice in 3D view
• Axis indicators in 3D view
• View any of the 4 views fullscreen
• 16 indexed colors
• Paint / add / erase in slice view
• Sprite sizes (1, 1, 1) - (64, 64, 64)
• Rotate / pan / zoom 3D view
• Paint / add / erase in 3D view 
• Slice fill (not pictured)

---------------------------------------------------------------
Language     files          blank        comment           code
---------------------------------------------------------------
Java           380          10137           4127          26833
PHP            309          10275           5858          26722
CSS              6            641             68           3242
GLSL            54            407            111           1579
Javascript      14            262             89           1192
XML              9            111             12            574
HTML             3              8              0             42
DOS Batch        1              0              0              1
---------------------------------------------------------------
SUM:           776          21841          10265          60185
---------------------------------------------------------------