Patches

Surface patches

In order to perform the radiosity calculations, Qrad3 creates "patches" for all of the map's surfaces. These patches each cover a specific area of the surface, and are used to track the lighting absorbed, and control the light emitted from that area.

By default, these patches are 64 units square. Multiple patches are created for surfaces bigger than 64 units. Sometimes the light emitted from these patches can appear very spotty. It is most often seen on normal surfaces that are very close to light-emitting surfaces. This is because a single light is created for every light-emitting patch, and 64 units is sometimes too far a distance to cast smooth lighting. Qrad3 provides the -chop command line option which can be used to create smaller-sized patches. Unfortunately it affects ALL surfaces in the map, and can drastically slow down the program. It may even cause errors on medium to large maps, because there is a limit on the number of patches that can be created.

-choplight #

To help provide a better solution to the problem, ArghRad adds this option. This tells the program to divide only light-emitting surfaces into the specified sized patches (all other surfaces will still use the default size, 64). Decreasing this value can help eliminate the spotty lighting with far less slowdown than by using plain -chop. There is also far less risk of encountering the max number of patches error. Values should generally be greater than 16. This option does not affect warping (liquid, etc.), or sky surfaces.

Example:

   arghrad.exe -choplight 32 mymap.bsp
-chopsky #

This option works the same as -choplight, but only for light-emitting sky surfaces. It is provided as a separate option, as sky can sometimes cover large areas of the map, and may not even need the same extra chopping. ArghRad takes extra measures to prevent splotchy sky-surface lighting, so -chopsky is probably rarely needed. It may be most useful in conjunction with "_sun_diffade".

Example:

   arghrad.exe -chopsky 32 mymap.bsp
-chopwarp #

This option works the same as -choplight, but only for light-emitting warping surfaces, like liquids. It is also provided as a separate option, as these surfaces can sometimes cover large areas of the map, and may not need the same extra chopping. ArghRad takes extra measures to prevent splotchy warped-surface lighting, so -chopwarp is probably rarely needed.

Example:

   arghrad.exe -chopwarp 32 mymap.bsp
-chopcurve #

This option works the same as -choplight, but only for phong shaded surfaces. It defaults to 32, or to the value of -chop, whichever is smaller. This helps these simulated curves blend together better. This option is probably most useful if your map has a large number of curved surfaces. In this case you could increase the -chopcurve value which would take less memory, less time, and help avoid the max patches error.

Example:

   arghrad.exe -chopcurve 64 mymap.bsp
-radmin #

In order to perform the radiosity calculations, qrad3 creates "transfer" data to track which patches send light to which other patches. The amount of light transferred is based on factors such as distance and relative surface angles. -radmin sets a minimum cutoff point that can reduce the amount of transfers that are performed. This can seriously reduce the memory requirements and compile time. Be aware that this can create very noticable changes in the level's appearance. Tiny decimal values will look best. The default is 0.

Example:

   arghrad.exe -radmin 0.001 mymap.bsp