OpenGL lighting is complex and can be confusing. Defining surface normals is important, and understanding ambient, specular, diffuse, and emitting light sources can create realistic effects. Optimizing a scene can improve frame rate. Sometimes, using texture images or arranging geometry can eliminate the need for multiple light sources.
OpenGL® lighting is one of the most complex, and sometimes least understood, aspects of three-dimensional (3D) computer graphics programming. It can be used to add necessary and realistic finishing touches to a rendered scene, but it can also be computationally demanding and ultimately confusing when the effects are not easily achieved. Some elements, such as defining surface normals, can be easily understood while other parts of the lighting model, such as the division of different types of light, may require more study to fully understand. There are usually two problems when working with OpenGL® lighting: rendering speed and quality. There are a few tips that can help you achieve an acceptable proportion of both, but ultimately you will need to find a trade-off between quality and speed.
A commonly encountered problem, especially for those new to OpenGL® lighting, is that every vertex in a scene must have its own surface normal defined. Without normals, the renderer will instead use a single constant, causing everything in a scene to appear flat and unshaded. One trick when defining normals is to use values that are not perpendicular to the surface, but instead face in a different direction. This will change the way light is rendered on the surface and can be used to easily create noise or rock textures, a process known as bump mapping.
To achieve good, and potentially unique, effects in a scene using OpenGL® lighting, you need to fully understand what ambient, specular, diffuse, and emitting light sources entail. A scene filled with fog can be made more realistic with a high, gray ambient value. Similarly, special effects such as fire or exposed lights can be achieved with materials and light sources. Layering and combining the four basic patterns is what can make a scene look more realistic.
It is important to understand that OpenGL® lighting requires a large amount of processor power for each frame rendered. This means that optimizing a scene can help you get a better frame rate. Some things that can reduce render time are to use as few light sources as possible, minimize the amount of illuminated surfaces, and avoid algorithms or extensions that process the final framebuffer multiple times. Shifting the lighting in a scene can also have a negative effect on performance and should be avoided when rendering speed becomes an issue.
One final tip on using OpenGL® lighting is knowing when not to use OpenGL® lighting. It can be easy to think of placing objects and emitting lights in a scene wherever you are in reality, but this can quickly become impractical. Instead, many lighting tricks can be done through illusions using well done texture images that have the lighting already drawn onto the surface. Likewise, arranging the geometry of a scene can sometimes eliminate the need for multiple light sources by hiding certain problem areas or by allowing a single source within a hollow composite object to shine through multiple planned openings.
Protect your devices with Threat Protection by NordVPN
