Time for action – working on the wall

1. Open the file ch3_Wall.html in your HTML5 browse. You will see something similar to the following screenshot:

   

2. Now, open the file again, this time in your favorite text editor (for example, Notepad ++).

3. Go to the vertex shader (Hint: look for the tag <script id="shader-vs" type="x-shader/x-vertex">). Make sure that you identify the attributes uniforms and varyings that are declared there.

4. Now go to the fragment shader. Notice that there are no attributes here (Remember: attributes are exclusive of the vertex shader).

5. Go to the runWebGLApp function. Verify that we are calling initProgram and initLights there.

6. Go to initProgram. Make sure you understand how the program is built and how we obtain references to attributes and uniforms.

7. Now go to initLights. Update the values of the uniforms, as shown here.

     gl.uniform3fv(prg.uLightDirection, [0.0, 0.0, -1.0]);
     gl.uniform4fv(prg.uLightAmbient, [0.1,0.1,0.1,1.0]);
     gl.uniform4fv(prg.uLightDiffuse, [0.6,0...