Today’s update on Stok3d is perhaps not as useful as the previous post, but I certainly had fun working on it. Or as we say in Dutch with a word blatantly stolen from German: it’s “spielerei”.

Demos:

I’m going to post the demos first this time. Saves you some scrolling effort, because the explanations below are rather boring

• Parallax Mapping : Move and turn towards the edges of the screen to see the extrusion of the texture best. A PhongFilter is added as a second filter, making it slower but the effect becomes more obvious.
• Water Shading 1 – Ocean : Reflects or refracts light depending on the view angle and the surface relief. It animates a perlin noise filter to generate a water heightmap.
• Water Shading 2 – Ripples : Same thing, but with a simple drawn ripple effect. The difference between refracted and reflected light is more obvious here.

Edit: Even if you have Flash Player 10, you still might get an update request. That is because these demos require the version of 10.0.22 concerning recent Pixel Bender bugfixes.

The source code for these demos can also be found on Google Code.

Useful updates

Some updates I did involved some bugfixes and performance-related updates. I also added a NormalMapUtil class, which provides a basic API to generate and manipulate normal maps. The main features are the generateFromHeightmap and drawFromHeightmap methods. Since height maps (or bump maps) are generally easier to come by (and to make), these methods generate a normal map for you. generateFromHeightMap creates a new BitmapData, drawFromHeightMap uses an existing BitmapData that you provide (useful if you need to generate one on every frame). The NormalMapUtil class furthermore allows you to invert the components of the normals, in case a normal map reflects the light in the wrong directions.

Water Shading

A new shader filter that was added is the WaterShadingFilter. If you remember your high school physics, depending on the view angle, the surface either reflects the light or lets it pass through and refracts it (which is called the fresnel effect).  To put it simply, when looking at water at a shallow angle, it seems like a very reflective surface, but when looking straight down into it, you can see through it but it’s a distorted view. The reflection uses a combination of environment mapping and phong shading, while the refraction is a simple displacement mapping technique. The DisplayObject to which the filter is applied is used as what’s underneath the surface, ie: the refracted light. The ripples seen in the demo are not made by the filter, but are custom written to manipulate the normal map.

Parallax Mapping

Another new filter is the ParallaxFilter, which performs (you guessed it) parallax mapping. It’s a technique like bump and normal mapping, in the sense that it tries to give more depth to a 2D texture. It does so by displacing texture coordinates based on a height map and view direction to the coordinate that it would normally have in 3D space. This causes the texture to look extruded and more detailed. For more (and better) information, check the article on wikipedia. Stok3d implements an iterative variation. It’s a bit slower but takes care of overlap issues and can handle sharp edges.

That’s it! For now, it’s back to Farbe, and… some other things

Last week I posted an example of Environment Mapping using FP10′s native 3D and Pixel Bender. The reactions were quite positive, which motivated me to push the concept a bit further and create more shaders using Pixel Bender. These new additions all work in the same fashion, ie. as Filters which need to be updated whenever the target object (or if provided: light position) changes.

I created a project on Google Code for this, dubbed Stok3d (as I was positively stoked at that specific point in time). It’s a mini-library at this point, but in the future there’s potentially more to it than shaders; Z-sorting for instance: although it has been done already, it wouldn’t be a bad idea to create something specifically for Stok3d and have more functionality in one place. But… zat’s for ze futuah! At least for now, it will be easier to commit bugfixes and updates.

Demos

In the order from low cpu usage (and less visually interesting) to high cpu usage (and more interesting):

• Diffuse Shading: Basic shadowing, no specular highlights or normal map support
• *Phong Shading: Phong shading with support for normal and specular maps
• *Environment Mapping with Phong Shading: Combination of cubic environment mapping and Phong Shading, supporting normal and specular maps.

* Although Stok3d is distributed under the GNU GPLv3 license, the textures are NOT covered by this license. In particular, the blast door and hangar door textures, normal maps, and specular maps are made by Florian Zender (http://www.florianzender.com) and are used with his kind permission. Check out his work, it’s quite impressive!

Source

The source for the examples as well as the library can be found on Google Code. It’s available over svn or as a downloadable archive.