Sky Dome Tutorial
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- This is a tutorial for how an artist can create and export a Skydome asset and an area designer can then configure it for use.
Overview
A Sky Dome, or Sky Box, is essentially just a Static Asset with a sky texture on the inside. So to create one, an artist simply needs to take a big box, dome, or any other shape desired and place an appropriate .dds Texture on it.
This tutorial explains in detail how to create a Sky Box:
- The artist creates the asset in 3ds Max or Maya
- The artist then exports the asset, and places it in the Repository
- The game designer accesses the asset via the Asset Library, and configures it for use as a sky box. Create a library asset, right click it, and set is as a skybox.
Skyboxes VS Dynamic Sky
The choice between using a skybox and using HeroEngine's Dynamic sky system is mainly one of artistic control, though Dynamic Sky is a slightly greater burden on the client. But as of build 1.69, skyboxes can now be used in conjunction with Dynamic Skies using alpha channels.
The use of skyboxes allows an artist to create the exact look of the sky in an area. Also, surrounding scenery, such as buildings and mountains, can be included in the skybox. To achieve the same effect purely with Dynamic Sky, scenery would need to be applied to billboards placed in the area.
Technical Art Notes
There are a few important technical art characteristics with regards to skyboxes.
- Size - Skyboxes appear massive when displayed in HeroEngine, however they are actually rendered in camera space and are drawn behind all other objects. Therefore, the actual mesh should be no more than a few meters in size.
- Shape - While referred to as a sky "box", the sky can really be any closed polygon hull including a hemisphere, sphere, cylinder, pyramid, or other shape of your choice.
- Texture - Use a standard 2D texture with appropriate texture coordinates. Do not use a cube map or other specialized texture
Creation by the artist
First, decide what shape to use for the "box". Domes, or hemispheres, are often preferable because they lack obvious corners that must be disguised. Also consider how the texture will map onto the "box". Some sky textures look distorted because they are a panoramic picture, formatted to map perfectly to a dome or sphere.
Then, simply create that shape in Maya or 3ds Max and reverse the normals of the shape so that they face inwards.
Multiple Layers
Skyboxes may contain more than one closed polygon hull. By using a smaller dome inside a larger one, an artist can create effects like a scrolling cloud layer by utilizing transparent textures and scrolling UVs. Each polygon shape will require its own HeroMaterial.
Creating a Sky Material
Create a Hero Material, 'Shader' if you are using Maya, using the appropriate texture file and apply it to the "box". Remember to use .dds formatted textures!
3ds Max Hero Material
Maya Hero Shader
- Set the material to ignore since you will never collide with it.
- Set No Illumination, Glow, and No fog to on by selecting the check boxes.
- If the artist painted an alpha in this sky, it can be used as a glow mask by selecting it in the diffuse channel.
Export
- Using the Current exporter package, export the skydome to your Art Depot as if it were a static asset
- Using the Repository Browser, upload it to the Repository
Use by the area designer
- Open the Asset Library
- Go to the appropriate library tab where you want to keep your sky.
- Right click in the open white space and select "Add Item..."
- Change the icon so that it appropriately reflects a thumbnail of the artist's art.
- Right-click on the Skydome icon, and select Set as > Skydome.
Now HeroEngine understands that it is a skydome and treats it accordingly. The dome will follow the camera and render behind everything else in the world, creating the appearance of a vast, encompassing sky, despite the small size of the skydome.
Skydomes can be added to an area using the Environment Panel.
