Let’s Light It Up!

While we will take a closer look at rendering techniques in depth later on in the book, it always brings a sense of achievement when you can get some color on the screen. Not just a sprite and a pretty background, but painting 3D objects with light and texture.

In this chapter, I will go over the fundamental ways that OpenGL works with light and textures to give you more to experiment with as you continue to investigate these types of projects. You will learn how to add lighting and materials to the project we are developing throughout. It will provide you with the skills to develop better-rendered images that will assist you in visual confirmation that your code is working as it should.

In this chapter, we will cover the fundamentals of visualization, including the following:

• Adding Lighting Effects
• Placing Textures on Meshes

Technical requirements

In this chapter, we will be using Python, PyCharm, and Pygame, as used in previous chapters.

Before you begin coding, create a new folder in the PyCharm project for the contents of this chapter called Chapter_5.

The solution files containing the code can be found on GitHub at https://github.com/PacktPublishing/Mathematics-for-Game-Programming-and-Computer-Graphics/tree/main/Chapter05.

Adding Lighting Effects

Lighting in computer graphics serves the same purpose as it does in the real world. It provides definition to the rendering of objects, making them seem embedded in the virtual world. The way that light is perceived depends on the surface treatment of the objects. These treatments are defined as materials and will be discussed in the next section.

Light sources consist of three primary lighting interactions:

• Ambient light represents the background light in an environment that doesn’t emanate from anywhere. It’s like the light that you can still see in a room when all the lights are out, but you can still make out the shapes of objects because light might be leaking into the room through windows. It is light that has been reflected and scattered so much that you can’t tell where it is coming from. It’s a basic coloring and although it doesn’t emanate from a particular source, in computer graphics, it is assigned as...

Placing Textures on Meshes

Materials are the surface treatments given to polygons that make them appear solid. The coloring-in of the polygon plane gives the illusion that it has substance and is more than its surrounding edges. The surface treatment applied interacts with the lighting applied to give the final appearance.

Just like lights, materials have different ambient, diffuse, and specular colors. Each of these interacts with the corresponding lights to determine the final effect seen. For example, white diffuse light shone on a diffuse green cube will reflect the color green. Although white light is hitting the cube, the green color of the cube determines what light gets reflected. White light is when all the color channels for R, G, and B are turned on, hence the (1, 1, 1) value. If the cube is green, then its color is set to (0, 1, 0). Essentially, it’s the channel that the light and the material both have turned on that is reflected. Of course, it is a little more...

Summary

This chapter has been a short examination of lighting and texture that help to bring depth to a scene and make objects appear solid. Besides the lists of vertices and UVs that we’ve used, you will discover later in the book that a 3D mesh can possess many other sets of values used for a multitude of rendering effects. But for now, you have enough skill in displaying a simple mesh and adding a texture to it.

In the next chapter, we will add more flexibility to the project we are creating by working more with the main loop. In addition, we will improve the application architecture to make it more extensible by giving simple rendered objects access to more behaviors.

Answers

Exercise A:

glLightfv(GL_LIGHT0, GL_AMBIENT, (0, 1, 0, 1))

Exercise B:

glLightfv(GL_LIGHT0, GL_SPECULAR, (0, 1, 0, 1))
glEnable(GL_LIGHT0)
glLight(GL_LIGHT1, GL_POSITION, (-5, 5, 0, 1))
glLightfv(GL_LIGHT1, GL_DIFFUSE, (0, 0, 1, 1))
glEnable(GL_LIGHT1)
while not done: