|Texture Property Name||environmentmap|
|Description||Defines the custom environment map to use for reflections|
|Excepted Data Source||4 component image|
|Data Range||0 or greate for the component 1 to 3 and 0 to 1 for the component 4|
|Default Value||(1, 1, 1, 0)|
The environntmap texture property defines the environment map to use for reflection. By default the Graphic Module produces an environment map (or something similar) for reflections itself dynamically if the module requires one. Using this property the environment map to use for reflections can be forced. This can be useful for example to achieve special effects for example by using a renderables. This allows to show foreign environment content like an object reflecting a different world. Another possible use is to pre-calculate a special environment map of a cockpit inside for a HUD. This way the game developer has full control over the environment map and the Graphic Module is not required to deal with dynamic environment map creation.
Environment maps can exist in different formats ranging from Cube Maps all the way to 2D Atlas reduced formats. All these are defined in the Drag[en]gine using an image. This works since images can have a depth or layers (z coordinates). To define a proper Cube Map for use with this texture property the image has to have a depth of 6 with each layer specifying a single face of the Cube Map. The ordering of the faces is the following:
Each layer has to be oriented along the other two positive axes. Hence the positive x axis layer has to be oriented with the image x and y axis along the cube map y and z axis.
You can use a 3 component or a 4 component image as environment map. If a 4 component image is used the alpha color component (component 4) is used to blend between the image defined in this texture property and the environmemt map reflections the Graphic Module would use without the use of this texture property. This allows to create a custom environmemt map with holes where the outside environment map shows true. To use again the cockpit scenario the pre-calculated environment map can set the area covered by the hood to 0. Reflections from this direction would then use the environment map reflections calculated by the Graphic Module instead of the environment map provided by the game developer.
Environment maps created by the Graphic Module are typically high definition range images if the Graphic Module uses high definition range rendering. The environment map set with this texture property should also be high definition range if possible.
The source is typically a floating point image with 3 or 4 color components with values 0 or greater for the color components 1 to 3 and 0 to 1 for the color component 4.
The default value for this texture property is (1, 1, 1, 0) which is a fully transparent Cube Map literally disabling a custom environment map.
( TODO: example image )