Implementation: LightedTexCube

Overview 

In previous examples, we saw that Position, Color, Texture data were sent to draw cubes. In this post we  will discuss how to implement  Phong lighting models and other lights such as Directional, Point and Spot Lights. For this surface normals needs to be sent as VBO data. They look as shown at the bottom. They look elongated because aspect ratio is not applied.

Details

System  class diagram

LightedTexCube derives from TexturedCube class. It overrides mesh with an instance of CubeMesh to generate geometry. 

LightedTexCube

LightedTexCube is derived from TexturedCube class. It illuminates the textured cube as per settings done in the light parameter. Utility class gLightingUtil is used for lighting related settings.

Members

Name	Description
cameraPosition	Specifies the location of the light source for diffuse and specular illumination.
light	An instance of LightingUtil. It contains settings for illumination.

Methods

Name	Description
Init	This method overrides the base class Init method to load texture.  Generates the vertices data consisting of surface normals in non indexed mode and later sets them up in VBO buffer.  It also passes an input to use BlinnPhong or Phong illumination and also type of light source as defined by LightSource enum.
UpdateUniforms	This method overrides the base class UpdateUniforms method. Firs t it updates  "cameraposition" uniform. Next it updates lighting related uniforms by calling Updateshader method on light. Finally it c alls base class UpdateUniforms method to send rest.
vertexShaderSource	This method overrides the base class vertexShaderSource method. It returns the vertex shader code to render the cube object.
fragmentShaderSource	This method overrides the base class fragmentShaderSource method. It returns the fragment shader code to render the cube object based on light source type.

LightingUtil

It defines illumination properties of the light source and reflection properties of the material in the light and material members.

Members

Name	Description
material	An instance of Material sub class. It contains settings of the material property for reflection.
light	An instance of Light sub class. It contains settings for illumination.

Methods

Name	Description
UpdateShader	Updates the uniforms that contains copies of the information stored in light and material members.

Output

The output looks as shown below.