HDR Lighting Basics

Category:HDRCategory:Level Design
== Overview ==
The Source Engine supports two independent sets of light maps in one compiled map: one for HDR (High Dynamic Range) and one for LDR (Low Dynamic Range). With LDR lighting, mappers have to supplement dark areas with additional point and texture lights to help make these areas visible. HDR light maps alleviate this with auto-exposure calculations, removing the need for "fake" lights. Having both LDR and HDR lighting can more than double the size of the light map data in the final BSP file.
== Basic compiling of a HDR map ==
The simplest thing to get HDR working immediately is to recompile your existing map with the latest VRAD.
If you're using the compiler built-in to Hammer, compiling your map with HDR is very simple:
# Open the .VMF file in the Hammer editor.
# Choose Run Map from the File Menu.
# Set BSP, VIS, and RAD options to Normal.
# Under the RAD section, check the HDR check box.
# Click OK to start the map compiling.
:
== VRAD command-line arguments for HDR ==
If you don't use the Hammer built-in compiler, you can use the following commands with VRAD for use on the command-line: -both, -ldr, -hdr, and -final. Now a .BSP file can contain two sets of lightmaps for both LDR and HDR. To compile both add the command -both to VRAD. If you want to compile just the LDR version add -ldr, and for HDR only add -hdr. Another new command that was added for this release is -final which is used to increase the quality of skylight and indirect light by spending more CPU time firing rays.
== Running HDR in the Source Engine ==
The Source engine can be run in both HDR and LDR modes. If a map has been compiled with HDR lightmaps, and HDR is enabled (set to "Full") in the Video Settings for the game, HDR will be automatically enabled when the map is loaded. Due to the separate lightmaps that are created for HDR and LDR, cubemaps must be built for both HDR and LDR modes.
HDR can also be enabled or disabled via the command-line when launching the game with the following command:
+mat_hdr_level 0/1/2
* Set to 0 for LDR, 1 for LDR with bloom on HDR maps and 2 for full HDR and bloom on HDR maps. The lightmaps for the level will be reloaded if the value is changed while a map is loaded.
=== Launching the game with HDR enabled ===
To force HDR and blooming to be enabled when running the game, add +mat_hdr_level 2 via one of the following methods:
* In the Hammer Run Map dialog, adding the command to the Additional game parameters.
* Right-clicking the game in the Steam Library and choosing Properties..., and entering the command into the Launch Options.
* Creating a shortcut to the game on your desktop, then adding the command in the Windows Properties dialog.
* If you use a .BAT batch file to run the engine, add the command to your batch file.
== Building HDR and LDR cubemaps ==
;To build cubemaps for both LDR + HDR, see Cubemaps - Building cubemaps section.
You must do this every time you compile the map or the cubemaps will not appear correctly.
== Selecting an HDR skybox ==
Another thing you can do easily to improve the quality of the HDR effects is to select an HDR skybox.
To select an HDR skybox in Hammer:
# Select Map properties from the Map menu.
# Enter the name of an HDR skybox in the Skybox Texture Name field (e.g. sky_example_hdr). See List of skies for a list of available skyboxes.
# Recompile the map with the new skybox.
The sample map sdk_hdr_example.vmf in the SDK samples includes the entities for this demonstration.
For a description on how to create new HDR skyboxes, see HDR Skybox Creation.
== See also ==
* HDR Lighting Settings - for more information on how to customize HDR settings.
* HDR Skybox Creation
* 
* Advanced HDR