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One of the key questions that mappers frequently raise is how to define and place light sources. While placing light sources is generally easy, this section explains the types of available lighting techniques in Ca3DE and the options to create light sources for each.

The Ca3D-Engine implements two different types of lighting techniques:

• Radiosity-based lighting and
• dynamic lighting.

The two lighting techniques are quite distinct from each other, and each comes with a set of feature of its own. Nonetheless, both techniques peacefully coexist in the Ca3D-Engine and mappers frequently employ both in a single map.

One of the most fundamental lighting techniques in computer graphics is the Radiosity method. Radiosity methods compute lighting based on a physical model, and it is the nature of the underlying mathematics that characterizes the features of the technique.

The big downside of Radiosity is that it requires a preprocessing step. This preprocessing step can be computationally very expensive and thus taking a long time to complete. It is implemented in a special tool called “CaLight”, which is one of the map compilers that are covered in sections Compiling Maps for Cafu and Compiling Maps at the Command-Line.

The fact that Radiosity is slow to precompute also means that it cannot work with dynamic objects: Radiosity takes walls and any other static object into account, but anything that moves will not influence the Radiosity-based lighting result.

Good news about Radiosity-based lighting is that once the preprocessing step it complete, it is fast. Independently of the number of light sources or complexity of the scene, Radiosity-based lighting provides very good performance at run-time during the game. It is therefore a natural choice for large-scale base lighting of any level.

Even better, Radiosity lighting results looks stunningly good. No matter what hardware vendors tell you about their latest products, no matter what game developers tell you about dynamic lighting (as I too do, see below), none of these techniques can beat the realism of lighting generated by Radiosity methods. Based on an accurate physical model, the natural appearance of lights and shadows is unique to Radiosity methods. [Screenshots!, link to my thesis in See Also section]

For these reasons, Radiosity was the first lighting technique implemented in Ca3DE.

• Radiosity lights are area light sources.
• (whose irradiance is defined with the material),
• radiosity point light source entities,
• sky light.

• hardware accelerated.
• dynamic light+shadow entities