Template:Int lvl design This tutorial will cover the more advanced lighting techniques used in Source maps. If you are new to lighting in Hammer, you may want to read the basic light tutorial first. To begin the tutorial all the possible ways to create light will be covered and then onto all the settings related to playing with lighting. This will then be followed by a set of more in depth mini articles on how to use and take advantage of the lighting you’ve been introduced to.
- 1 Light Entities
- 2 Related Items
- 3 Techniques
- 4 Conclusion
This is a list and rundown of each entity you can use to cast physical light. The titles for each section link to the page for the entity itself. It’s important to remember that these entities cast light in some form or another.
A directional form of the light entity, its cone-shape allows for a directed form of light. Again it can be turned on and off through inputs, though a switchable light_spot may cause lightmap errors. This is a static light that can be pointed in any direction. And is also recommended for common use.
An invisible light source that can change and move over time. Its position can change and it can be aimed at moving objects. Dynamic lights are recalculated continuously, which means they have a higher processing cost but are much more flexible than static lighting. Use this type of light sparingly, because it is the most expensive light for the engine to render.
A directional light cast in only one direction, the direction is decided by the key values entered. The key is that the light is only cast from the
tools/toolsskybox texture. The first key value, Brightness, controls direct lighting. This approximates direct sunlight. The second key value, Ambient, controls indirect lighting from the sky. This is the diffuse light that is cast on every face that can "see" the sky. Basically the shadow the light leaves.
Related ItemsThis is a list of all the topics related to lighting itself but don't emit light. While none of these emit any physical light their all essential to creating effects with it. If it’s controlling the lighting of entities or controlling an antlion's shadow they all fall under lighting effects. HDR lighting effects. Unless used with fully implemented HDR it has little/no effect.
A lightmap is the lighting data of each face. The stored light is then added to the face giving it brightness. The lightmap's scale refers to the number of texture pixels per light pixel (luxel). Smaller values mean more luxels, thus a better quality but larger BSP size and compile times.
TechniquesThis covers how to use the mentioned items to create effective lighting. Before, a lot of practical knowledge was covered. But knowledge is useless unless it's utilized well. The next few sections are specifics about how to use all the information to create better lighting in your maps.
Creating a True Light Source
Creating a true light source can often be a challenge. Simply placing a light entity does nothing to explain where that light came from or why its there. A true light source is one that appears like it should be there and sits comfortably within the environment. Often a good light is made up of multiple entities. Commonly there are two: one for the light and one for its source like a prop_static or a func_detail with an appropriate texture.
The first step is to determine what lighting sources are available. Look for textures or models that would be emitting light. Filtering by the word 'light' in either the model or texture browser works well. Now pick one that fits the feel of the room(i.e. industrial lights for an industrial scene) and place that model or texture in the room. For this example pick the light shown on the right and place it with a prop_static.
Now that there's something that looks like it would emit light, the next step is to create the light it's emitting. Look at the source that’s been chosen. Is the light going to be slightly colored? Is it going to be only in one direction? Use the assorted light entities to create the effect and set the properties up right. With the given example the light is going to be focused in one direction, so pick a light_spot. Next, this is a bright light, so give it a brightness of 200. Then look at its colour, it's a very white light so confirm it's a white light being emitted. Now line it up compared to the prop_static, alter the angles so it appears to come from the prop static.
Now there’s a light lined up to its source, there may be a problem though. Sometimes the model used for the source is going to block the light that the light is trying to cast. So go into the prop_static's properties and make sure that it has "Disable shadows" set to "yes". This means that the source of the light will not block the light itself. Now that it’s a working setup, group them so they always stay together. Now if you need more lights you can copy this group.Another way to create a high quality light source that portrays real life better but doesn't compromise on performance is combination of a light and light_spot. Position the light_spot as described above, but position the light around 50 units away from the model that is the light's source. Make this light have a brightness of approximately 50 and is the same colour as the light_spot. This will often create a more correct form of glow on surfaces that the light_spot often lacks.
Static vs. Dynamic
There are many advantages, performance wise, of using static light sources over dynamic ones. Static lights carry no additional processing weight so their use is essential to fast rendering maps. Dynamic lights can carry a lot of rendering weight and can be expensive to use in your map. Its important to know where and when to use each type of light and avoid using the wrong type.
Firstly static lights are calculated during the VRAD compile process; therefore, there is next to no calculations done in game it merely needs to render the light calculated which is a fast process. The common static lights are light, light_spot and light_environment but there are conditions that can change this. The problem which comes with static lights is the fact that it is static. While they allow very precise and detailed lighting no special effects can be given with static lighting because it’s not going to change.
Dynamic lighting on the other hand comes in two flavors. There are the switchable lights and the true dynamically calculated lights. Each has its own processing weight but both are expensive to render and should be used sparingly.
Switchable lights are the same as static lights in that they use lightmap information compiled during RAD. A light is set as being switchable by one of three things such as giving it a name, giving it a style, or giving it a pattern. Regular lights that don't support dynamic effects are the lights generally used as switchable lights, this includes lights like light, and light_spot but not light_environment. Switchable lights use a set of two lightmaps on and off. Switchable lights alternate or blend between the two lightmaps, this allows partial brightness while keeping it to just two lightmaps. This gives all the benefits of the static lighting but allows it to change and be partially dynamic. Say you have two switchable lights shining on the same face, how many lightmaps are needed?
- Light 1 & 2 ON
- Light 1 ON, 2 OFF
- Light 1 OFF, 2 ON
- Light 1 & 2 OFF
That's four states in total. You add a third switchable light and it goes up to eight lightmaps. Here becomes the problem with switchable lights, it becomes expensive in lightmaps to create all the possible states. So expensive in fact that there is a hardcoded limit that means you can only have two switchable lights affecting the same face. There is a slight solution though, the lights with identical names will all be given the same lightmap, so you can have 50 switchable lights with the same name shining on the same face. Because of the extra lightmaps switchable lights use it increases the amount of time it takes RAD to run, increases file size, and also uses up system resources when it alternates between them; however, a switchable light sat in one state or the other has little or no more effect than a static light.
True dynamic lighting is something that has to be built into the entity itself, its most often recognized by the Parent property within the entity. The entities with the built in dynamic effect are light_dynamic and point_spot. Point_spot is special in the unique fact that is has a flag that can enable it as dynamic or static, its set to dynamic by default and can often catch you off guard. The dynamic process done for dynamic lights is run entirely within the game, this means it has little to no effect on the RAD compile or file size but it will slow down your map. The system slowdown caused by dynamic lights is generally consistent as the light needs to be rendered continuously. Such entities should only be used when the source of the light is moving, if the light itself is not meant to move then it shouldn't be a true dynamic light. If it’s merely meant to turn on and off it should be switchable. No movement should be static. If used improperly the costs of using dynamic lighting will outweigh the benefits of doing so. Dynamic lights should be used even more sparingly than switchable lights. Another down side to the dynamic light is that to simplify the calculations it doesn’t run process like reflection and diffusion, this results in harsher simpler looking lights.
Static lights are easy on the engine and give great detail, but dynamic lights represent the possibility for movement and change, but cost a greater amount to render and loose detail. The easiest way to tell what effect the dynamic lights are having is to test your map with the
+Showbudget command. This allows you to figure out when an effect is too much and lighting effects are slowing down your map. Good use of dynamic lights can only improve your map, but they can be a costly effect.
Lightmaps store nearly all the lighting information in Source BSPs, and their efficient use equates directly to efficient lighting. They are the key contributor to BSP file size: efficient usage is a must for anyone wanting their map to be downloaded off the cuff, and preferable for everybody.
Lightmap scale is the basic component of optimisation. It determines how detailed lighting information will be for a given face (you can see the effects above). The more information stored, the bigger the file size. Small lightmap scales allow for fine details but come at the cost of a bigger file (performance is unchanged). Large lightmap scales create fuzzier lighting but lead to smaller files. Determining when a face needs a detailed lightmap and when it doesn't is therefore the task.
This can mostly be done by eye from a compiled map. Look for the faces that receive high contrast shadows or specific details, as they are often the best candidates for low (i.e. detailed) lightmap scales. Faces with slow blends or lighting that only slightly differs across them on the other hand can safely have their scale raised.
For a working example look to the hallway shown on the right. One side shows the in-game compiled version and the other side shows the lightmaps as displayed in Hammer. The lightmap view is easy to access: left click on the word Camera in the top left of your 3D view, and from the drop down select 3D Lightmap Grid. In this view, yellow faces have smaller than default scales, white faces are at the default, and blue are larger.
The hallway we are looking at has wall mounted lights and a few ceiling lights as well. In the picture it's clear to see where the lightmap scale has been increased and decreased. The front of the pillar has an increased lightmap because of the light source on its face, to catch all the detail. This is not such a major problem as the pillar is a small thin face and the only area with a lower scale. The floor and a few of the walls along the edge have been scaled up, as looking at the in-game rendering little to no detail or change is seen in the lightmap; they are excellent candidates, the floor especially so with its large size. The other faces have been left at the default resolution as they all have some play of shadows or changes in brightness. While not detailed or essential enough to warrant a smaller scale, increasing the scale would only serve to create poor looking lighting as the lack of detail would show.
While technically possible to decrease the entire scales across the entire map for crisp shadows, the compile time and filesize expense almost always outweighs the benefit. Finding the balance between increasing and decreasing the lightmaps may take a few lighting compiles and some guesswork, but performed correctly can both enhance your map and reduce its filesize.
Quick and Effective RAD
The fastest way to compile RAD is to avoid compiling as much of it as possible untill it becomes neccesary. While working on a map the best approach is to not compile the entire map at once and to not compile every time new lights are added. If the map is constantly recompiled just to find out what changes a couple of new lights made all progress will slow to a crawl. Essentially the trick is to compile less data fewer times, but also learning when and how to get away with it. The easiest way to compile less data is to isolate the area the lighting effects are being created in and forget the rest of the map. This is what the Cordon tool is designed for, sectioning off parts of the map, its one of the best ways to speed up compile times. When creating a new room always cordon it off before begining the lighting process, the room is the only new item and should be the only room being compiled, but don't be too stingy. Light may leak from other rooms and is an important consideration. Truly faster compiles only come from less surface area or less detail, the only other option is a quick compile. A quick compile can show roughly how well lit an area is without spending twice as long doing it. Generally full compiles will produce a slightly brighter ambient and smoother shadowing, they look prettier but do not do much to change the overall brightness except increasing it slightly, quick compiles only directly light faces and don't take into account diffusion and reflection aswell as other effects. The best approach to compiling less often is to determine neccesity, if the purpose of the compile is to test if the NPC does his script properly theres no need to compile lighting as it does not affect the NPC. Another way to compile less is to standardize the lighting in the map, if the lights are the same its already known how they light a room and it is not neccesary to compile the map to judge the lights effects. The first step is to create light sources; models, lights and effects that combine to create 1 reusable grouped lighting effect. Every time that type of light, paste a new version of that light in your map. Its already known what lighting effects it will produce so theres no longer a need to compile the lighting in that section to guage how well lit it is. With at least 5 light types and strategical placement an entire map can be properly and well lit on the first full RAD compile.
ConclusionThis covers the base of all lighting effects found in standard source games. Any lighting affect that can be achieved is a mixture of all or some of these effects; however, don't get comfotable though change is coming.
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