BSP surface flags

This will explain all surface flags you can use. Surface flags can be accessed either by right-clicking a surface and choosing Surface Properties, or by selecting a face and then cliking on the Surface Properties button in the upper toolbar.

Invisible

Surface is all invisible during render.
- Light ray tracing can go through.

If a surface that touches subtracted spaces or belongs to a solid brush is flagged as invisible, in game players will see a HOM, because there is nothing behind to be rendered, just a void.

Masked

Surface is rendered as masked (for non-masked textures). Keep in mind that masked textures still render the surface as masked.

If a surface that touches subtracted spaces or belongs to a solid brush is flagged as masked (or textured with a masked texture), in game players will see a HOM, because there is nothing behind to be rendered, just a void.

Translucent

Surface is translucent.
- Light ray tracing can go through.
- No volumetric/distance fog supported.

It's not possible to control how much translucent a surface is. However, you can more or less control how much visible that surface is. Brighter lights make the translucent surface more visible, while complete darkness make that surface invisible.

If a surface that touches subtracted spaces or belongs to a solid brush is flagged as translucent alone, in game players will see a HOM, because there is nothing behind to be rendered, just a void.

Force view zone

Render the poly regardless of its zone mapping.

During the zone mapping process, polys will sometimes be flagged as part of Zone 0, causing them to be invisible when the player is within the level.

Level designers can detect this class of hole by moving "into geometry" (i.e., outside the level) while viewing the level from an editor window set to "Zone/Portal View." If the hole is replaced by a polygon coloured unlike the rest of the polygons in the zone (usually dark grey), the "hole" can usually be patched by setting the Force View Zone flag.

The patch can immediately be verified by moving inside the level.

Modulated

Render surface as modulated (uses the grey colour as the transparency colour).
- No volumetric/distance fog supported.

Can be combined with mirror like translucent + mirror, except that, uhm... the surface's texture will be modulated instead of tranlucent.

Fake backdrop

Render the surface as sky (using a skybox outside the level and placing a SkyZoneInfo actor in center of it).

Surfaces flagged with fake backdrop are skipped during the lightmap stage. If there is no skybox to render, surfaces with this flag will be displayed unilit in game and in editor.

Two Sided

Surface is rendered regardless which side ur standing (mainly used for flat sheets).

This can cause some confusion with wrap zones because if the sheet is flagged with "two sided" it can be missplaced, the wrong side of the sheet may be facing the player. In many maps there are wrap portals that instead of rendering the other side, display a HOM effect. The player goes in, but instead of being instaly teleported to the other side, player gets stuck "inside" the wrap zone, when he/she leaves that zone, he/she finds himself on the other side. Flipping the sheet 180 degrees should fix that.

Two sided sheets can't be two sided mirrors. It flickers and doesn't work properly.

U/V - Pan

Texture on the surface is constantly panning to one direction (in surface direction using speed defined in ZoneInfo > ZoneLight > TexUPanSpeed/TexVPanSpeed).

Unfortunately there isn't a flag of sorts to create rotating textures :(.

High/Low shadow detail

Controls sharpness of light shadows. High detail makes them sharper, low detail makes them fuzzier. Both flags together makes it even fuzzier, basically Super Low Detail.

More specifically, controls the relative resolution of a surface's lightmap. For example: a lightmap can be a 256 x 256 texture map for the whole level. Surfaces may take up 16 x 16 or 64 x 16 pixels of that lightmap's area, but can never go beyond 256 x 256 pixels. Higher scale values = lower surface's lightmap resolution. Lower scale values = higher surface's lightmap resolution.

No smooth

Draw the surface with no texture smoothing.

Special poly

Unused? Does nothing?

Special lit

Surface will ignore all lights but lights with "bSpecialLit = True".

Small wavy

Texture is slowly panning in random directions.

Dirty shadows

Makes the surface be covered with random shadow spots. The lightmap on that surface looks "dirty", like splotches of mud, or the marks on the walls and floors after a battle of baloons filled with paint or colored water.

Bright corners

Don't allow black spots cover the corners of the surfaces.

Seems that lamp textures or small lamps made out of brushes not being lighted up properly is caused by the extremly low resolution of lightmaps. The lightmap itself is just too low res to store enough pixels for that tiny surface, thus, that surface remains almost black even with very bright lights close to it.

No bounds reject

Failure of the bound rejection code below causes holes that appear and disappear as you move around the polygon. Flagging the polygon (or in some cases, several adjacent polygons as well) with No Bound Rejection will eliminate this problem.

To verify that the polygon in question is suffering from this problem, select all surfaces, then toggle the flag. The missing polygon should appear when "No Bound Rejection" is flagged.

NOTE: Bound Rejection is a performance optimization, disabling this code entirely may result in a performance reduction ranging from 10% to 30% depending on level complexity.

Unlit

Surface is unlit.
- No volumetric/distance fog supported.

Portal

Special flag for sheets for defining where zone changes cut.

Like mirrors, if a wrap zone portal is in the line of sight of another, there is a hard limit of up to 3 portal zones being rendered inside other portal zones. It's possible to make a pair of wrap portals facing each other to create the illusion of an infinite world, but the engine will not render infinite wrap zones inside another.

Mirror

Surface is rendered as mirror (can be combined with Translucent/Environment flag).

Caution! Mirrors can cause huge slowdowns on slower machines, because the engine has to render things twice for the mirror's reflections.

If one mirror is in the line of sight of another, the engine has a hard limit of up to 3 inter-reflections to prevent it from wasting power calculating infinite reflections.

Mirros aren't considered during lightmap stage, which means, mirrors won't reflect off light.

Mirror can be combined with translucent to make a shiny surface. However, it's not possible to control how much translucent the surface's texture is and the diffuse / specular reflection levels of that surface.

Environment (227g only)

Draw the surface with an environment mapped texture overlay on it.
- No volumetric fog supported.