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Adding Lights
[Tutorial 1 - Loading a Simple Model]

Creating Lights

It is fairly straightforward to add run-time lights to the application. In this section we will add two lights: an ambient and a directional light.

• Add two global variables, for the two lights to main.c:

      static RwRGBA ForegroundColor = {200, 200, 200, 255};
      static RwRGBA BackgroundColor = { 64,  64,  64,   0};
  

      RpWorld *World = NULL;
      RwCamera *Camera = NULL;
      RtCharset *Charset = NULL;
      RpLight *Ambient = NULL;
      RpLight *Direct = NULL;
  

• Next add the following code, which creates the lights for us, and adds them to the world. Lights are created using a default color of white.

      static void
      CreateLights(void)
      {
          Ambient = RpLightCreate(rpLIGHTAMBIENT);
          if (Ambient)
          {
              RpWorldAddLight(World, Ambient);
          }
  

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

      }
  

• Add a line to the Initialize3D() function to call CreateLights(). We are not too concerned here about error handling - if the lights cannot be created then the application can continue with no lights.

          /* Create an empty world if not loading a RWS... */
          World = CreateWorld();
          if( World == NULL )
          {
              RsErrorMessage(RWSTRING("Cannot create world."));
              return FALSE;
          }
          /* Create the lights */
          CreateLights();
          /* Create a camera using the democom way... */
          Camera = CreateCamera(World);
  

• Compile and run your code, and when you load a new cube you should see the following screen. This shows us that the cube is no longer black because our lights illuminate it.
  

  Destroying Lights

  As was mentioned before, destroying objects is every bit important as creating and using RenderWare Graphics objects. The final step in this exercise is to destroy the lights when the application shuts down. We will write a DestroyLights() function for this.

• After the CreateLights() function, add the following code, that undoes the steps used to create the lights.

      static void
      DestroyLights()
      {
          if (Direct)
          {
              RwFrame *f;
              RpWorldRemoveLight(World, Direct);
              f = RpLightGetFrame(Direct);
              RpLightSetFrame(Direct, NULL);
              RwFrameDestroy(f);
              RpLightDestroy(Direct);
              Direct = NULL;
          }
  

          if (Ambient)
          {
              RpWorldRemoveLight(World, Ambient);
              RpLightDestroy(Ambient);
              Ambient = NULL;
          }
  

      }
  

• Make a call to DestroyLights() in the Terminate3D() function. A good place to do this is immediately after the RpWorldForAllClumps() iterator function. You must destroy the lights before the world is destroyed, however.

• Compile and debug the code. Use a breakpoint on DestroyLights() to make sure that you understand when the lights are destroyed.

Next...

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