NewLight Point/Bugs and limitations
Transparency issues with deferred lighting
None of the available shaders that support transparency can render shadows and lighting on on objects if transparency is enabled. Usually other games and engines use deferred shading for opaque objects, then switch to forward rendering for transparent objects, but Black Mesa rendering is not doing so.
Example from bm_c2a5g, expected that the shadows from the ropes and the plastic road cone on the window will be rendered, but this doesn't happen.
The same scene, but with
Counter-Strike: Global Offensive cascade lighting which is not using gbuffer.
Deferred lighting is also incompatible with transparency for VertexLitGeneric and Lightmapped_4WayBlend, it shows one of the lighting layers applied to the color of the transparent texture.
No $translucent. Behind the wall placed lighting and some models with in a small room.
With $translucent. Now the player can see everything, but only what the light covers.
This issue also applies to brushes with no transparency, but which is a part of a func entity with a transparent brush (the only exception is func_detail). This happen even if transparency used for shader that doesn't shows one of the lighting layers. Doesn't work only if brush has alpha texture.
This sticker is brush, that is part of func_brush, which uses glass as part of itself. Flashlight off.
This sticker is brush, that is part of func_brush, which uses glass as part of itself. Flashlight on.
The same will happen if used $decal material parameter.
Example from bm_c1a1c.
Similar issue will happen if overlay/decal is applied on a geometry with transparency.
The metal speaker is overlay that use $alphatest, but lighting from the health charger is still visible, because the overlay is applied on the transparent window.
If a func entity or model uses render mode Glow (3) or World Space Glow (9) - they will show one of the lighting layers as well. This means that you can't use these renders to make your brush transparent, you will need a separate texture with alpha texture and material with $translucent.
Example with multiple props and brush entity, they are using Glow render mode.
Using other render modes (except Normal (0) and Don't Render (10)) on a brush entity will cause many rendering issues. Example in this short video.
The cloak material shader parameter will also cause this issue, even if object is not transparent at the moment.
Example in bm_c2a3c. The female assassin is not transparent, but the lighting layer is still showing through.
There is not much workarounds. In some cases, $alphatest can be used, because it can give similar to $translucent result, it will also allow object to create dynamic shadows.
Confirm:Is there more ways to get transparency issues ?Clipping near new light BBOX volume corners (newLight_Point only)
If a client is near newlight_point's BBOX volume corner, the lighting starts clipping on the client side in a form of triangle shape. The size of clip depends on how close the client to the BBOX corner volume, it can be minimal or hide lighting completely. This bug disappears (the triangle shape goes away) if the client is in BBOX or is not near one of the 4 corners. The distance and how far/close should be the client directly depends on BBOX volume size.
Example with enabled BBOX rendering.
Brush polygons clipping deferred lighting
Sometimes brush polygons clip deferred lighting. Can be fixed if divide invalid brush into two parts.
Note:Usually happens if used fast compile settings for a map.
First example with mat_wireframe 0.
First example with mat_wireframe 1.
Second example with mat_wireframe 0.
Second example with mat_wireframe 1.
Deferred lighting shines through nodraw texture
The toolsnodraw texture doesn't create dynamic shadows for dynamic light sources, there is no option for this feature to be enabled/disabled.
Workaround:If a dynamic light source illuminates face that the player will never see, use cheap textures with low resolution, a good solution would be toolsblack or any UnlitGeneric texture.
The scene from player's position in bm_c2a2a map.
The scene from the opposite side.
Objects with refract shader self refract if illuminated by deferred render
Objects with refract shader in their own refraction disable self, to escape some problems. However - objects with refract shader illuminated by deferred render refract self because of game can't tell the depth of objects because of the transparency, what you are see in the pictures is just the lighting layer applied to the color of transparency texture.
as_c3map01 - flashlight disabled, everything looks fine.
as_c3map01 - flashlight enabled, now this magnifying lamp refract self.
Similar issue happen if model with refraction behind wall with refraction.
Flashlight disabled, everything looks fine.
Flashlight enabled, now this wall show one of magnifying lamp deferred lighting layers.
Workaround:Divide model into two separate parts, one should use only textures with refraction, the second without textures with refractions.Viewmodel lighting in frame buffers where it should not exists
Despite the separate render pass for viewmodel lighting, it still appears in shaders where used the player's camera. This affects _rt_FullFrameDepth, _rt_PowerOfTwoFB, _rt_WaterRefraction and shaders that use these.
Example for _rt_FullFrameDepth and _rt_PowerOfTwoFB.
This also affects Refract and motion blur shaders.
Refract.
Motion blur.
This bug doesn't appear with disabled viewmodel rendering (r_drawviewmodel 0).
Strange "holes" when player's camera is at a great distance
In some cases may will appear strange "holes" when player's camera is at a great distance. Strange bug that occurs quite rarely. It is affected by game resolution, for example in bm_c4a1b1 this bug shows up well with a resolution wtih 1920x1080, but with 3840x2160 the light source from the teleporter flickers, but does not form a hole.
Confirm:Does it happen with newLight_Spot ?Workaround:Can be fixed with NormalBias value increasing.
Example in bm_c4a1b1, the green teleporter light source starts to glitch when player move certain distance (crossbow zoom doesn't effect to this bug, unlike HEV zoom).
Black Mesa, map bm_c4a1b1. NormalBias - 1.
Black Mesa, map bm_c4a1b1. NormalBias - 5.
Black Mesa: Black Ops - Restored, bmops_map_2. NormalBias - 0.5.
Black Mesa: Black Ops - Restored, bmops_map_2. NormalBias - 1.5.
Gbuffer doesn't draw during cubemaps building
This leads to lighting and other affects will not be shown in cubemap image, which in some cases significantly affects the difference between the scene in the cubemap and the real scene.
The actual scene (used dynamic yellow lighting for the crystal).
The scene during cubemaps building (the tunnel appears to be dark, although the crystal glows due to $selfillum).
The scene from the cubemap image in the game on RPG viewmodel (the crystal is visible, but no the cave).
Gbuffer doesn't draw in 3D Skybox
Due to gbuffer is not included for sky_camera, this causes gbuffer effects not displayed in 3D Skybox, including lighting and godrays.
Example, sky_camera is used in this small area with model for npc_alien_grunt_melee and newlight_point, but the lighting and godrays is not visible in 3D Skybox.
Materials reload causes new lights with enabled shadows to disappear
Only for new lights which uses shadows. This issue happen when you open Hammer while game is opened, when a client disable cubemaps with mat_specular 0, when a client reload all materials with mat_reloadallmaterials, e. t. c. Can be fixed with save reload.
Before
mat_reloadallmaterials.
After
mat_reloadallmaterials. Note that the dynamic lighting from the tripod spotlight disappeared.
Deferred lighting does not draw with -tools
If you don't use Full Screen - deferred lighting will not draw.
In
Full Screen.
Out
Full Screen.
Broken water transition for viewmodel
After the Necro Path update, viewmodel lighting does not transit properly between water surface. Only for water with enabled refraction.
Example with crowbar, note that the top part is not lit.
Godrays incorrect work with $translucent
Godrays (also disk) all time fully rendering through textures with material shader parameter $translucent, because of this you will see unexpected results like in the picture (the same issue happen if used material shader parameter $decal). Disable godrays when you need or use $alphatest if it'll give resualts similar to $translucent. You also can try use some other tricks to escape this problem.
Bug example in bm_c1a3c.
Sign from other side.
Godrays fully draws through water
Deferred lighting doesn't fully draws through water, unlike godrays.
Black Mesa: Blue Shift - bs_c3m0c.
Godrays doesn't process viewmodel if player is underwater
Necro Patch fixed the old issue with godrays that wasn't processing models above water. This fix caused new issue, now godrays doesn't process viewmodel if player is underwater. Doesn't happen with func_water and func_water_analog.
Player is not underwater.
Player is underwater.
Godrays can't be displayed in monitors and reflections
Godrays is post process effect that depends on player screen. That means that they can't water reflections or monitors can't show it.
Note:Godrays for monitors and reflections was added with Necro Patch. However, this is disabled in the code by default, because it didn't work correctly. There is no way to enable this feature.
An example.
An example.
Godrays doesn't work with refraction
Even if godrays is behind surface with refraction, they will not correspond to the refracted scene, an object can be refracted, but not its shadow from the rays. Godrays will also not blend with refraction color.
Example, note that the magnifying glass is refracted, but not rays.
Shadow acne with moving lights
Shadow acne (also can be called "projection clipping") appears for moving lights with shadows if parent is moving at high speed. This issue appears even if used a very high value for nr_shadow_max_passes_per_frame console variable. This issue causes black squares or dark floors due to incorrect shadow overlaying. Multiple examples can be seen in this 1 minute long video.
Example in bm_c1a1c. Before the elevator falls.
Example in bm_c1a1c. During the elevator falls.
Can be partially fixed with NormalBias value increasing. Also, if your moving light is just simple decoration (the puzzle crystals from Xen is great example), it is highly recommended to disable shadows to save limits and performance.
NormalBias- 1
NormalBias- 10
Shadowmaps split boundary artifacts (newLight_Point only)
newLight_Point uses 1–4 separate shadowmaps to cover its projection volume. When an object is positioned close to the boundary between these shadowmaps, the shadow may appear broken, clipped, or misaligned. This artifact is most noticeable with point lights using low-resolution shadowmaps, where precision issues become more visible.
Shadows have noise
This noise appeared with Necro Patch, greatly spoils blurry shadows. The only workaround is to make ShadowRadius value very low, but then the shadows will become extremely sharp and stepped.
An example.
Shadows doesn't appear instantly after save load
The game doesn't load shadowmap for dynamic lights instantly, which is why light sources remain without shadows for a short time. This issue doesn't depends on how powerful device the game running at. The more dynamic lights with shadows level has, the more noticeable this issue, because for the game it takes longer to load shadowmaps. Example in a short video.
Before save load.
After save load (note that the large shadow from the bucket disappeared).
Workaround:Enable in worldspawn settings Level Fade In to hide this issue, this setting also will hide some other issues with loads in 
Black Mesa. env_fade entity can be used for this as well.Shadows doesn't appear instantly if light wasn't enabled
If dynamic light source was disabled on spawn, shadows will not appear instantly, this also happens if player's camera didn't see this light source enabled initially. It is noticeable in dark areas. Example in this short video.
Workaround:Use 0 value for light intensity on spawn. When should be turned on - set required value via SetIntensityForLight input with delay of ~0.1-0.5 seconds after turning on.Shadows low passes per frame if used a lot of lights with shadows
Sometimes many lights with shadows sets low values for nr_shadow_max_passes_per_frame cvar. This cause shadows to be looking a lot less natural.
Workaround:Very easy to fix with point_servercommand, just place logic_timer which will fire nr_shadow_max_passes_per_frame 28 command each 2 seconds.
nr_shadow_max_passes_per_frame - 16
nr_shadow_max_passes_per_frame - 28
Viewmodel doesn't support self-shadowing with deferred ligths
Unlike cascade shadows - viewmodel doesn't support self-shadowing with deferred ligths. Not a bug, but this is not what you expect from real life, it also isn't so with env_projectedtexture.
Here you can see how one of gluon gun switches create shadow that fall on other part of gun.
Light spot illuminates gluon gun, but lighting just ignore viewmodel and fully shine through, although only the side of the gun should be light.
Spot lights have sharpness bug if shadows enabled
It is most noticeable if spot light is at not a right angle. It greatly degrades quality of shadows. Issue can be partially fixed if make NormalBias value bigger. Also can be minimized with shadow quality, range, outer and inner angles.
An example.
bm_c1a2b.
BUGSUCK1.jpg)
BUGSUCK2.jpg)
Moving newLight_Spot clipping if shadows enabled
Even with low speed, newLight_Spot clipping when rotating, but only if shadows enabled. With pause this bug get fix.
An example.
bm_c1a3a - emergency light sources.
bs_c3m0a - scene with the stucked scientist.
bs_c3m2a - Dr. Rosenberg scene.
