TannSanWiki - GenEngine/CloudSystem

2006-07-01 18:38:55

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:38:55 and 2006-07-01 18:55:36

Additions:

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:36:54 and 2006-07-01 18:38:55

Additions:

lock the facing angle of the sprite when the camera comes within half of the sprite radius. This removes the Red Sea effect
detect the angle between the sprite�s locked orientation and the vector to the camera, and adjust the transparency of the sprite, which also produces the side effect of making that section of the cloud appear less opaque

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:34:22 and 2006-07-01 18:36:54

Additions:

Textures are 32-bit, and used for both color and alpha
By creating interesting features inside the textures that resemble eddies and wisps, we are able to create more realistic looking clouds with fewer sprites.
We keep the video memory cost low by placing all 16 textures on a single 512x512 texture sheet, which spares the cost of switching textures between drawing calls to the video card
When the binary file is loaded into the game, the sprite is given a random rotation within the range.
- We have found that it looks best to give the cumulus cloud bottoms a narrow range (-5 to 5 degrees) and all other sprites the full range of rotation (0 to 360 degrees).
- We do not apply a rotation to non-square sprites.

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:33:44 and 2006-07-01 18:34:22

Additions:

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:32:09 and 2006-07-01 18:33:44

Additions:

traverse the list of clouds and eliminate any sprite whose 3-D distance to another sprite is less than a threshold value. This reduces overdraw in the final rendering, and also eliminates redundant sprites created from overlapping boxes. We have found that a cull radius of 1/3 of the sprite height works well for typical clouds, and 1/5 ... 1/6 of the sprite height yields dense clouds.

Comparison for /Gen Engine / Cloud System of 2006-07-01 18:29:13 and 2006-07-01 18:32:09

Additions:

There are generally 20 � 200 boxes for each 16 square kilometer section of clouds
1 � 100 sprites per box depending on the cloud density

Comparison for /Gen Engine / Cloud System of 2006-07-01 15:00:03 and 2006-07-01 18:29:13

Additions:

each cloud as 5 to 400 alpha-blended textured sprites
The sprites face the camera during rendering and together comprise a 3-dimensional volume
Render them back-to-front based on distance to the camera

Comparison for /Gen Engine / Cloud System of 2006-07-01 14:58:39 and 2006-07-01 15:00:03

Additions:

A cloud “type” system. I researched cloud types and created an array of their features. So cumulous clouds would be big and fluffy and others would be long streaks. This allowed me to say “create 10 cumulus and 5 altocumulus clouds” and each cloud group in that type would apply the correct positioning and spacing needed to achieve the correct look. I created the data but only applied it to cumulus so far.

Deletions:

A cloud “type” system. I researched cloud types and created an array of their features. So cumulous clouds would be big and buffy and others would be long streaks. This allowed me to say “create 10 cumulus and 5 altocumulus clouds” and each cloud group in that type would apply the correct positioning and spacing needed to achieve the correct look. I created the data but only applied it to cumulus so far.