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Pre-lighting
[Tutorial 5 - Creating a World]

We could add additional lights into the world to make the other walls visible. In this tutorial, however, we will use the prelighting feature of the 3ds max exporter to compute illumination and store this in the exported file. This means that RenderWare Graphics does not need to perform lighting calculations on the vertices of the world. This is a technique that can dramatically increase rendering performance in real applications. If your worlds do not require dynamic lighting, then you should export the static geometry using prelighting.

• In 3ds max add a single omni light. Position it slightly to one side of the room. Adjust its brightness so that it shines completely white light.
• In the Attenuation section of the command panel select both Use and Show for the Far attenuation. Ensure that Decay is set to None.
• Adjust the Far Start and End parameters so that extent of the light completely contains the room. In the illustration below values of 100 for both Start and End were sufficient. You may need to adjust these values depending on where in the scene you have placed the omni light.
  

• Use the Assign Vertex Colours utility to store the colors that are computed for each vertex by 3ds max's lighting equations into the model. You will need to use the "Mix Vertex Colors" option.
• Save the scene.
• We will export this asset with a different filename: RenderWare->Advanced Settings

  The RenderWare Graphics Export Wizard creates an asset in the Asset Manager tab. This asset is used for export. The project name will be used to name the file.

• Change the Project Name to tutorial5p
• Below "Asset" there should be an asset called "tutorial5". The template used is "Static World".
  

  A Static World template exports static geometry. To modify the options used to create this static world:

• Select the Asset Template tab.
• In the "Template" drop down, select Static World.
• Check that the Vertex Prelights option is set to TRUE. This option exports the model with results of the lighting. The default value is TRUE.
  

• In the Asset Manager, right click the asset "tutorial5" and choose Export, to export the asset.

• Modify the Initialize3D() function in main.c to load this new .rws file.
• Compile and run the application. Look around the world using the right mouse button.

  You should find that the world is now loaded and is prelit. However, the back wall is still being illuminated by the RenderWare Graphics directional light and appears fully bright. On this wall no prelighting is visible. You should now be in a position to understand that the default camera position is looking towards this fully bright wall.

  Our next step is to modify the run-time directional light so that it does not illuminate the world. RenderWare Graphics lights can be configured to illuminate atomics, or worlds, or both. By default they illuminate both, which is not what we want to happen in our application.

• In the CreateLights() function, modify the ambient and directional lights. Before the lights are added to the world, make calls to RpLightSetFlags() and set the lights to illuminate only atomics (rpLIGHTLIGHTATOMICS).

      static void
      CreateLights(void)
      {
          Ambient = RpLightCreate(rpLIGHTAMBIENT);
  

          if (Ambient)
          {
              RpLightSetFlags(Ambient, rpLIGHTLIGHTATOMICS);
              RpWorldAddLight(World, Ambient);
          }
  

          Direct = RpLightCreate(rpLIGHTDIRECTIONAL);
  

          if (Direct)
          {
              RwFrame *f = RwFrameCreate();
              RpLightSetFrame(Direct, f);
              RpLightSetFlags(Direct, rpLIGHTLIGHTATOMICS);
              RpWorldAddLight(World, Direct);
          }
  

      }
  

• Compile and run your code.
• Add a few cubes by pressing F1.

  This time the RenderWare Graphics light does not illuminate the back wall, and we can see the prelighting. The cubes that you have added show that the RenderWare Graphics directional light continues to illuminate atomics, and also indicate the direction of the light.

  

Next...

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