GlInstanceID

GlInstanceID is a shader interface and storage mechanism in the OpenGL API. It is used to provide a unique identifier for objects that are drawn to the screen, allowing developers to write shaders that can access and manipulate these objects in a data-driven way. Each instance of a mesh is assigned a unique instance ID, which can be used to perform operations such as per-instance transformations, lighting, or animation.

GlInstanceIDs are typically used with Artists and Technical Directors who need to create complex scenes with many objects, and want to enable runtime flexibility and dynamic updates to these scenes. By using instance IDs, developers can write shaders that can adapt to changing scene requirements, without having to rewrite the shader code or recompile the shader.

GlInstanceIDs have several key benefits, including reducing the amount of shader code that needs to be written, improving runtime performance, and enabling more complex and dynamic scene creation. They also allow for decoupling of shader code from scene data, making it easier to manage large-scale artwork.

A key feature of GlInstanceIDs is the ability to use a single shader program to render multiple types of objects, without having to replicate shader code for each instance. By using a uniform instance ID as a parameter in the shader, the GPU can perform more局scene-driven processing, such as per-instance transformations and lighting.

The use of GlInstanceIDs has been particularly influential in the development of 3D game engines and visual effects software, where they enable the creation of complex, dynamic scenes with a high degree of realism and interaction.