What is a common design approach to reduce draw calls in a 3D scene?

Combining meshes where appropriate is a common design approach to reduce draw calls in a 3D scene. In 3D graphics, a draw call represents a request made by the CPU to the GPU to draw something on the screen. Each time a separate mesh is drawn, it usually incurs its own draw call; thus, having many meshes can quickly lead to performance bottlenecks, particularly on lower-end hardware.

By combining meshes, you can group multiple objects into a single mesh, which allows the GPU to render them in a single draw call instead of processing each one individually. This technique is especially effective for static objects that do not need to move or change, as they can be combined during the asset creation process or at runtime if necessary. Moreover, combining meshes can help to reduce memory overhead and improve rendering performance, making the scene more efficient.

The other options, such as using more separate meshes, increasing texture sizes, or adding more light sources, would not effectively help in reducing draw calls. Instead, they could lead to an increased number of draw calls or additional resource demands, negatively impacting performance.