The DarkMod Wiki - User contributions [en]

Light Properties

2008-10-02T14:05:15Z

Bear:

'''''NOTE: This is a first-draft article. It has not yet undergone quality control, so take information with a grain of salt as it is subject to change '''''

== Introduction ==

For Doom 3 (and subsequently, The Dark Mod), there are 4 different types of lights at our disposal. Each has their own advantages and drawbacks, and hopefully this article will help to familiarize The Dark Mod hopefuls with their use. For information on creating lights and a lot of other useful information, see [[A - Z Beginner Full Guide Start Here!]]

== Point Light ==

A point light is the default light (also the default for fog). No option must be checked to make a light a point light. A point light casts light, and subsequently shadows in all directions evenly, falling off after a distance defined by the light texture. This works best for most small indoor and outdoor lighting, like lamps, candles, fireplaces etc. For this reason, it is going to be the most used type.

== Parallel Light ==

A light is said to be parallel when the parallel checkbox is checked in the light inspector. It is subject to all the same options as a point light, but it has a few distinct differences. A parallel light tends to not care exactly where the entity itself is placed. The most important thing is where the light_center vertex is placed and where the light entities bounding box intersects with elements in your map.

The light_center vertex starts right in the middle of the entity. The main difference between the parallel and point lights is that a parallel light does not radiate from the origin around the entity itself. What controls the direction that shadows are cast is the placement of the light_center vertex. Shadows will run parallel (hence the name) to a line between this vertices and the light entity itself. As such, this makes it an excellent choice for sunlight or moonlight. As such, it has some of the elements of a point light and a projected light, it can seem to radiate in a circle (if you use the appropriate texture) whilst casting a shadow in any direction preferred.

Switch to Vertex mode in [[DarkRadiant]] to drag the light_center vertex of your selected light entity.

Posted by Greebo: Also, note that a parallel light will only light surfaces "matching" the direction of the "light vector" (origin minus light_center). All other surfaces will stay completely unlit, therefore it should be combined with an ambient light to achieve good lighting effects. [http://modetwo.net/darkmod/index.php?s=&showtopic=8091&view=findpost&p=159842]

What this means is, you can draw a line from the center vertex to the light entity's origin and on from there, and only objects in the direction of that line will be lit. The light won't light 4 walls of a room and the floor, it would only light one of the walls or the floor (or ceiling)

=== Troubleshooting ===

''I added a parallel light but I can’t see any light at all!''

Parallel lights can have some quirks. The light seems to fail and do nothing when intersecting multiple walls that are parallel to the face the light is actually casting on. It seems the light will work as long as it doesn’t intersect a face parallel to the one it is casting light on.

''I have a parallel light but it casts a jagged light on my floor!''

Similar to above, a parallel light can sometimes have anomalies when intersecting multiple walls and a floor. Since having the light intersect multiple walls when it can only cast on one of them, having a massive bounding box is pointless anyways so pay attention to what the light is touching and you should be fine.

== Projected Light ==

Projected light is just as the name suggests. It is probably more intuitive and easier to use than a parallel light and is better for things like projecting a window-shaped light on the floor of a room or a spotlight on a wall. To make one, select projected instead of the default omni option at the top of the light inspector.

This creates a triangular prism as the bounding box for the light (instead of a rectangular prism like a regular light), with the point ending right at the entity itself. This can be rotated using any of the XYZ rotation buttons or manually using DarkRadiant’s rotation tool (shortcut R).

You can also manipulate the projected light via the vertices (shortcut V to enable vertices dragging). By dragging the vertices in the center of the projected square, you can lengthen and change the angle of the projection while keeping the projected square the same size. To resize the projection, use the two side vertices in the correct XYZ grid view. Making the bounding box flat against a surface (like a floor) is usually unnecessary (for example, making a moonlight window light on a floor or wall), because with shadows enabled and making the projection long enough to intersect the plane on which the shadow is to be cast, the full shadow will be cast (its simple geometry and just requires minor toying).

As with all the lights, projected lights have a full range of color and texture options to let the mapper find just the effect they need, allowing you to create a great atmosphere for your map.

== Ambient Light ==

Ambient light is really just a lighting texture, but it is also a specific item that is needed in practically every map, so for those purposes it will be treated as if it were its own subset of lights.

An ambient light can be any form: it can be a point, parallel or even projected (though projected would probably be useless).

The only requirement of an ambient light is to use one of the available ambient light textures, accessible by opening the light inspector (with the shortcut L in DarkRadiant, and get used to using it), and selecting ambientlightnfo from the list.

Ambient Light is covered in more detail in [[A_-_Z_Beginner_Full_Guide_Page_2#Ambient_Light:_Gloom_not_Doom]]

== Light Settings ==
There are several settings with which to customize your lights. These settings allow the mapper to customize the look of a light (or a combination of lights) into a near infinity of looks. All are accessed through the light inspector (shortcut of L in DarkRadiant)

=== Color ===

The color palette allows the mapper to pick the color of the light emitted, arguably one of the most useful controls the mapper has over a light. To access it, click the button under the “Colour” heading. From there, adjust the settings until you find a correct color (can take some trial and error). In a game like The Dark Mod or Doom 3, where darkness is often more prevalent than light, the color picked often needs to be darker than expected. Without a direct brightness option, the color takes on this task. For a low level ambient light, the color picked would be almost pitch black. A pitch black light would not cast any light, but anything less than pitch black will cast a faint light. As such, it can take some trial and error to find the correct light for a situation, as intiailly, one is likely to pick a seemingly correct color only to find it is far too bright.

Remember: changing light settings or adding lights (and models) does not require re-compiling the map!

=== Parallel ===

Selecting this option turns the light into a parallel light (as opposed to a point or projected light). See [[Light Properties#Parallel Light]]

=== Do not cast shadows (fast) ===

As the name suggests, this setting causes the light to not cast shadows on any object. This can cause the light itself not being confined by walls, which can sometimes be beneficial and sometimes not. The main purpose of enabling this option is performance. Shadows are processor intensive and are not needed in some cases, so removing them wherever not beneficial to gameplay can vastly improve performance. Note that ambient lights never cast any shadows. Another way to improve performance similarly is to set the entity property on a model or func_static (this doesn’t work on worldspawn) <tt>noshadows</tt> to 1.

=== Skip Specular Lighting ===

Specular Lighting refers to a textures specular map, wherein a flat surface (such as a wall) is applied a texture with a specular component, which causes a surface to have shinier and duller parts on a flat surface based on the darkness of the corresponding location on the specular map. Not all textures have specular maps. Checking this option could improve performance or remove the effect if it is not wanted. [http://www.modwiki.net/wiki/Texturing#Specular_maps]

=== Skip Diffuse Lighting ===

Like Specular lighting, diffuse lighting also references an attribute of a texture, the Diffuse Map. Diffuse Maps determine the intensity and color of the light reflected off of the different elements of a texture (an example being the difference between bricks and the mortar in between, as well as different bricks having different properties as well giving a less bland appearance).
[http://www.modwiki.net/wiki/Texturing#Diffuse_maps]

=== Lighting Textures ===

The lighting textures are also accessed in the light inspector. The textures allow the mapper to chamge the intensity and falloff of a light. These also allow for animation of the light, such as a moving light for a fireplace, candle or torch etc, or flickering as well as sound. One can also apply a fog texture to the light (the only way built into doom 3 to create fog). Color is of a similar concern when creating fog, as noted in [[Light Properties#Color]]

== Further reading ==

A great tutorial on outdoor lighting can be found here:
http://www.katsbits.com/htm/tutorials/doom_3_lighting_outdoor.htm

{{tutorial-editing}}

Creating a Tower

2008-09-21T18:44:31Z

Bear: /* Conclusion */

==Introduction==
In making a tower, a couple decisions have to be made before it is even started.

Firstly: what is the purpose of the tower? Is it a lighthouse or a guard tower? Do you want it to taper near the top or be totally vertical? Either way is possible, but it requires slightly different steps. This tutorial will try to lead you through multiple ways to create a simple basic tower.

If this tower is part of a larger map (which is likely), my personal preference is to create a separate map just for the tower, and copy and paste the basic outline into the larger map later on to test scaling, or create a mock-up in the main map to give you basic dimensions.

==Tower Size==
Decide how large you want the tower to be at the base (or, if it doesn’t taper, how big you want it to be at the bottom and top).

There are multiple ways to do this: If you already have in mind items that you want to populate the tower with, place these and try to get an idea of the scaling. You can also place AI entities to try and gauge how big it is. When you’ve found an appropriate size, create a square brush (doesn’t need to be tall, its just for a guide in the top-down XY view) Move it out of your way so it doesn’t get in the way of the camera later (can move it strait up, will do the exact same thing).

[[Image:Creating_Tower_step1.jpg|400px]]

==Creating the first section==
Create a brush 1 px wide (or depending on your grid size it can be however large 1 grid mark is, 4 is probably easier to work with) along the left inside of your bounding box, meeting the box in the corner. Click in one of the side XYZ views and create a 3x3 patch mesh (clicking on the XYZ side views makes sure it doesn’t create a flat patch and instead a tall one).
[[Image:Creating_Tower_step2a.jpg|400px]]
[[Image:Creating_Tower_step2b.jpg|400px]]

===Making Curve===
Hit V to drag vertexes. Select the top most one and drag it to the exact middle of the top most side of your bounding box. NOTE: Be sure to shift click and drag over the vertex to get the two under the top one, otherwise you just get the top. The bottom vertices should be in the middle of the left most side of the square. Drag the middle vertexes into the corner of the bounding box. This should create a nice bevel. You will probably need to invert it so that it is visible from the outside instead of the inside (menu patch>matrix>invert) pieces.

[[Image:Creating_Tower_step3.jpg|400px]]
===Tapering Top===
Ignore this if you do not want to taper the tower near the top – Skip to [[Creating_a_Tower#Creating_inside_wall]]. Create another bounding box, much like the first, but smaller. Make sure it is perfectly square with the larger box and perfectly square overall. Using one of the side XYZ views, select the top 3 vertex and drag them to the side so that they can be more easily selected individually from the top view in a second. You might have to use 2 different side views to get them off the lower vertexes. Once you can select each one in turn, do the same thing you did for step 3, move top vertex to middle of smaller bounding box, bottom to middle of left smaller box and center vertex to corner of smaller bounding box. This should create a similar bevel to your first on the inside. At this point observe what it looks like from far away. '''You will note that the wall curves from the bottom to the top, this is because of the 3x3 nature of the patch. It has 3 vertexes in the middle that cause a curve. If you want a strait angle from top to bottom, select these 3 in a side view and drag them on top of the bottom vertexes. This will cause a sheer angle instead of a curve.'''

[[Image:Creating_Tower_step4a.jpg|400px]][[Image:Creating_Tower_step4b.jpg|400px]]

==Cloning sides==
Ensure this looks as it should and the clone your section, rotate once by Z axis, and place in the right upper corner. The edges should meet perfectly in the middle of the top side of the outer bounding box (might have to zoom in to be sure, from zoomed out it can be hard to tell). Copy both sections and flip twice and put at the bottom of the box. You now have your 4 outside pieces.

[[Image:Creating_Tower_step5.jpg|400px]]

==Creating inside wall==
This is much like the first steps. Create a box like your first, but smaller (if you tapered the top, make this one smaller than the box you created to do so). It needs to be square and square with your outside box. Size it to be realistic compared to how thick you want your walls to be. From the center of one side of the box to the center of the outside box will be how thick the walls will be. Repeat steps 2,3 and 5 and this time, don’t invert them (they should default be visible from the inside this time).
[[Image:Creating_Tower_step6a.jpg|400px]][[Image:Creating_Tower_step6b.jpg|400px]][[Image:Creating_Tower_step6c.jpg|400px]][[Image:Creating_Tower_step6d.jpg|400px]][[Image:Creating_Tower_step6e.jpg|400px]]
==Conclusion==
There you have it! Your basic tower shape is completed! Read an excellent tutorial on [[Spiral_Staircases]] and you will be well on your way. This is kind of a rough tutorial to get you through the basic steps to create the tower walls, decoration might be covered later. One thing to note, since this is made of patches, you can’t make holes for windows, so windows should be func_static’s that are not meant to be see-through (there are plenty of premades, or you can create your own).

[[Image:Creating_Tower_final_product_outside.jpg|400px]][[Image:Creating_Tower_final_product_inside.jpg|400px]]

2008-08-24T15:07:38Z

Bear:

'''''NOTE: This is a first-draft article. It has not yet undergone quality control, so take information with a grain of salt as it is subject to change '''''

For Doom 3 (and subsequently, The Dark Mod), there are 4 different types of lights at our disposal. Each has their own advantages and drawbacks, and hopefully this article will help to familiarize The Dark Mod hopefuls with their use.

== Point Light ==

A point light is the default light (also the default for fog). No option must be checked to make a light a point light. A point light casts light, and subsequently shadows in all directions evenly, falling off after a distance defined by the light texture. This works best for most small indoor and outdoor lighting, like lamps, candles, fireplaces etc. For this reason, it is going to be the most used type.

Parallel Light

A light is said to be parallel when the parallel checkbox is checked in the light inspector. It is subject to all the same options as a point light, but it has a few distinct differences. A parallel light tends to not care exactly where the entity itself is placed. The most important thing is where the origin vertices is placed and where the light entities bounding box intersects with elements in your map.

The origin vector starts right in the middle of the entity. The main difference between the parallel and point lights is that a parallel light does not radiate from the center around the entity itself. What controls the direction that shadows are cast is the placement of the origin vector. Shadows will run parallel (hence the name) to a line between this vertices and the light entity itself. As such, this makes it an excellent choice for sunlight or moonlight. As such, it has some of the elements of a point light and a projected light, it can seem to radiate in a circle (if you use the appropriate texture) whilst casting a shadow in any direction preferred.

[quote src=greebo http://modetwo.net/darkmod/index.php?s=&showtopic=8091&view=findpost&p=159842] Also, note that a parallel light will only light surfaces "matching" the direction of the "light vector" (origin - light_center). All other surfaces will stay completely unlit, therefore it should be combined with an ambient light to achieve good lighting effects.[/quote]

What this means is, you can draw a line from the origin vector to the light entity itself and on from there, and only objects in the direction of that line will be lit. The light wont light 4 walls of a room and the floor, it would only light one of the walls or the floor.

Troubleshooting:

I added a parallel light but I can’t see any light at all!

Parallel lights can have some quirks. The light seems to fail and do nothing when intersecting multiple walls that are parallel to the face the light is actually casting on. It seems the light will work as long as it doesn’t intersect a face parallel to the one it is casting light on.

I have a parallel light but it casts a jagged light on my floor!

Similar to above, a parallel light can sometimes have anomalies when intersecting multiple walls and a floor. Since having the light intersect multiple walls when it can only cast on one of them, having a massive bounding box is pointless anyways so pay attention to what the light is touching and you should be fine.

Projected Light:

Projected light is just as the name suggests. It is probably more intuitive and easier to use than a parallel light and is better for things like projecting a window-shaped light on the floor of a room or a spotlight on a wall. To make one, select projected instead of the default omni option at the top of the light inspector.

This creates a triangular prism as the bounding box for the light (instead of a rectangular prism like a regular light), with the point ending right at the entity itself. This can be rotated using any of the XYZ rotation buttons or manually using DarkRadiant’s rotation tool (shortcut R).

You can also manipulate the projected light via the vertices (shortcut V to enable vertices dragging). By dragging the vertices in the center of the projected square, you can lengthen and change the angle of the projection while keeping the projected square the same size. To resize the projection, use the two side vertices in the correct XYZ grid view. Making the bounding box flat against a surface (like a floor) is usually unnecessary (for example, making a moonlight window light on a floor or wall), because with shadows enabled and making the projection long enough to intersect the plane on which the shadow is to be cast, the full shadow will be cast (its simple geometry and just requires minor toying).

As with all the lights, projected lights have a full range of color and texture options to let the mapper find just the effect they need, allowing you to create a great atmosphere for your map.

Ambient Light:

Ambient light is really just a lighting texture, but it is also a specific item that is needed in practically every map, so for those purposes it will be treated as if it were its own subset of lights.

An ambient light can be any form: it can be a point, parallel or even projected (though projected would probably be useless).

The only requirement of an ambient light is to use one of the available ambient light textures, accessible by opening the light inspector (with the shortcut L in DarkRadiant, and get used to using it), and selecting ambientlightnfo from the list.

Ambient Light is covered in more detail in [[A - Z Beginner Full Guide Start Here!]]

There are several settings with which to customize your lights that will also be covered. These settings allow the mapper to customize the look of a light (or a combination of lights) into a near infinity of looks. All are accessed in the light inspector (shortcut of L in DarkRadiant)

Color:

The color palette allows the mapper to pick the color of the light emitted, arguably one of the most useful controls the mapper has over a light. To access it, click the button under the “Colour” heading. From there, adjust the settings until you find a correct color (can take some trial and error). In a game like The Dark Mod or Doom 3, where darkness is often more prevalent than light, the color picked often needs to be darker than expected. Without a direct brightness option, the color takes on this task. For a low level ambient light, the color picked would be almost pitch black. A pitch black light would not cast any light, but anything less than pitch black will cast a faint light.

Parallel:

Selecting this option turns the light into a parallel light (as opposed to a point or projected light). See further description further on.

Do not cast shadows (fast):

As the name suggests, this setting causes the light to not cast shadows on any object. This can cause the light itself to not be confined by walls, which can sometimes be a beneficial and sometimes not. The main purpose of enabling this option is performance. Shadows are processor intensive and are not needed in some cases, so removing them wherever not beneficial to gameplay can improve performance. This option would always be used with an ambient light. Another way to improve performance similarly is to set the entity property on a model or func_static (this doesn’t work on worldspawn) noshadows to 1.

Skip Specular Lighting:

Specular Lighting refers to a textures specular map, wherein a flat surface (such as a wall) is applied a texture with a specular component, which causes a surface to have shinier and duller parts on a flat surface based on the darkness of the corresponding location on the specular map. Not all textures have specular maps. Checking this option could improve performance or remove the effect if it is not wanted. http://www.modwiki.net/wiki/Texturing#Specular_maps

Skip Diffuse Lighting:

Like Specular lighting, diffuse lighting also references an attribute of a texture, the Diffuse Map. Diffuse Maps determine the intensity and color of the light reflected off of the different elements of a texture (an example being the difference between bricks and the mortar in between, as well as different bricks having different properties as well giving a less bland appearance).
http://www.modwiki.net/wiki/Texturing#Diffuse_maps

Lighting Textures:

The lighting textures are also accessed in the light inspector. The textures allow the mapper to chamge the intensity and falloff of a light. These also allow for animation of the light, such as a moving light for a fireplace, candle or torch etc, or flickering as well as sound. One can also apply a fog texture to the light (the only way built into doom 3 to create fog). Color is of a similar concern when creating fog, as noted in <link to color anchor>

Further reading:

A great tutorial on outdoor lighting can be found here:
http://www.katsbits.com/htm/tutorials/doom...ing_outdoor.htm

Light Properties

2008-08-24T15:05:55Z

Bear: New page: '''''NOTE: This is a first-draft article. It has not yet undergone quality control, so take information with a grain of salt as it is subject to change ''''' For Doom 3 (and subsequen...

'''''NOTE: This is a first-draft article. It has not yet undergone quality control, so take information with a grain of salt as it is subject to change '''''

For Doom 3 (and subsequently, The Dark Mod), there are 4 different types of lights at our disposal. Each has their own advantages and drawbacks, and hopefully this article will help to familiarize The Dark Mod hopefuls with their use.

Point Light:

A point light is the default light (also the default for fog). No option must be checked to make a light a point light. A point light casts light, and subsequently shadows in all directions evenly, falling off after a distance defined by the light texture. This works best for most small indoor and outdoor lighting, like lamps, candles, fireplaces etc. For this reason, it is going to be the most used type.

Parallel Light

A light is said to be parallel when the parallel checkbox is checked in the light inspector. It is subject to all the same options as a point light, but it has a few distinct differences. A parallel light tends to not care exactly where the entity itself is placed. The most important thing is where the origin vertices is placed and where the light entities bounding box intersects with elements in your map.

The origin vector starts right in the middle of the entity. The main difference between the parallel and point lights is that a parallel light does not radiate from the center around the entity itself. What controls the direction that shadows are cast is the placement of the origin vector. Shadows will run parallel (hence the name) to a line between this vertices and the light entity itself. As such, this makes it an excellent choice for sunlight or moonlight. As such, it has some of the elements of a point light and a projected light, it can seem to radiate in a circle (if you use the appropriate texture) whilst casting a shadow in any direction preferred.

[quote src=greebo http://modetwo.net/darkmod/index.php?s=&showtopic=8091&view=findpost&p=159842] Also, note that a parallel light will only light surfaces "matching" the direction of the "light vector" (origin - light_center). All other surfaces will stay completely unlit, therefore it should be combined with an ambient light to achieve good lighting effects.[/quote]

What this means is, you can draw a line from the origin vector to the light entity itself and on from there, and only objects in the direction of that line will be lit. The light wont light 4 walls of a room and the floor, it would only light one of the walls or the floor.

Troubleshooting:

I added a parallel light but I can’t see any light at all!

Parallel lights can have some quirks. The light seems to fail and do nothing when intersecting multiple walls that are parallel to the face the light is actually casting on. It seems the light will work as long as it doesn’t intersect a face parallel to the one it is casting light on.

I have a parallel light but it casts a jagged light on my floor!

Similar to above, a parallel light can sometimes have anomalies when intersecting multiple walls and a floor. Since having the light intersect multiple walls when it can only cast on one of them, having a massive bounding box is pointless anyways so pay attention to what the light is touching and you should be fine.

Projected Light:

Projected light is just as the name suggests. It is probably more intuitive and easier to use than a parallel light and is better for things like projecting a window-shaped light on the floor of a room or a spotlight on a wall. To make one, select projected instead of the default omni option at the top of the light inspector.

This creates a triangular prism as the bounding box for the light (instead of a rectangular prism like a regular light), with the point ending right at the entity itself. This can be rotated using any of the XYZ rotation buttons or manually using DarkRadiant’s rotation tool (shortcut R).

You can also manipulate the projected light via the vertices (shortcut V to enable vertices dragging). By dragging the vertices in the center of the projected square, you can lengthen and change the angle of the projection while keeping the projected square the same size. To resize the projection, use the two side vertices in the correct XYZ grid view. Making the bounding box flat against a surface (like a floor) is usually unnecessary (for example, making a moonlight window light on a floor or wall), because with shadows enabled and making the projection long enough to intersect the plane on which the shadow is to be cast, the full shadow will be cast (its simple geometry and just requires minor toying).

As with all the lights, projected lights have a full range of color and texture options to let the mapper find just the effect they need, allowing you to create a great atmosphere for your map.

Ambient Light:

Ambient light is really just a lighting texture, but it is also a specific item that is needed in practically every map, so for those purposes it will be treated as if it were its own subset of lights.

An ambient light can be any form: it can be a point, parallel or even projected (though projected would probably be useless).

The only requirement of an ambient light is to use one of the available ambient light textures, accessible by opening the light inspector (with the shortcut L in DarkRadiant, and get used to using it), and selecting ambientlightnfo from the list.

Ambient Light is covered in more detail in [[A - Z Beginner Full Guide Start Here!]]

There are several settings with which to customize your lights that will also be covered. These settings allow the mapper to customize the look of a light (or a combination of lights) into a near infinity of looks. All are accessed in the light inspector (shortcut of L in DarkRadiant)

Color:

The color palette allows the mapper to pick the color of the light emitted, arguably one of the most useful controls the mapper has over a light. To access it, click the button under the “Colour” heading. From there, adjust the settings until you find a correct color (can take some trial and error). In a game like The Dark Mod or Doom 3, where darkness is often more prevalent than light, the color picked often needs to be darker than expected. Without a direct brightness option, the color takes on this task. For a low level ambient light, the color picked would be almost pitch black. A pitch black light would not cast any light, but anything less than pitch black will cast a faint light.

Parallel:

Selecting this option turns the light into a parallel light (as opposed to a point or projected light). See further description further on.

Do not cast shadows (fast):

As the name suggests, this setting causes the light to not cast shadows on any object. This can cause the light itself to not be confined by walls, which can sometimes be a beneficial and sometimes not. The main purpose of enabling this option is performance. Shadows are processor intensive and are not needed in some cases, so removing them wherever not beneficial to gameplay can improve performance. This option would always be used with an ambient light. Another way to improve performance similarly is to set the entity property on a model or func_static (this doesn’t work on worldspawn) noshadows to 1.

Skip Specular Lighting:

Specular Lighting refers to a textures specular map, wherein a flat surface (such as a wall) is applied a texture with a specular component, which causes a surface to have shinier and duller parts on a flat surface based on the darkness of the corresponding location on the specular map. Not all textures have specular maps. Checking this option could improve performance or remove the effect if it is not wanted. http://www.modwiki.net/wiki/Texturing#Specular_maps

Skip Diffuse Lighting:

Like Specular lighting, diffuse lighting also references an attribute of a texture, the Diffuse Map. Diffuse Maps determine the intensity and color of the light reflected off of the different elements of a texture (an example being the difference between bricks and the mortar in between, as well as different bricks having different properties as well giving a less bland appearance).
http://www.modwiki.net/wiki/Texturing#Diffuse_maps

Lighting Textures:

The lighting textures are also accessed in the light inspector. The textures allow the mapper to chamge the intensity and falloff of a light. These also allow for animation of the light, such as a moving light for a fireplace, candle or torch etc, or flickering as well as sound. One can also apply a fog texture to the light (the only way built into doom 3 to create fog). Color is of a similar concern when creating fog, as noted in <link to color anchor>

Further reading:

A great tutorial on outdoor lighting can be found here:
http://www.katsbits.com/htm/tutorials/doom...ing_outdoor.htm