ARBdrawinstanced

ARB_draw_instanced is an extension to the OpenGL Shading Language (GLSL) that provides functionality to draw multiple copies of a model with the same geometry, material and texture, but with different instance information. This feature is useful in applications that require large numbers of instances of the same 3D object to be displayed on screen, such as in video games, computer-aided design (CAD) software, and virtual reality (VR) simulations.

The ARB_draw_instanced extension introduces several new uniforms and vertex shader inputs that allow developers to specify instance-specific data for each vertex of the model. The main concept behind instancing is to use a single vertex buffer object (VBO) for each instance of the model, where each instance has its own instance matrix and other instance-specific attributes. The extension also simplifies the process of drawing multiple instances by introducing a new drawing command, glDrawElementsInstanced, which can draw multiple instances in a single call.

Examples of applications that can benefit from ARB_draw_instanced include terrain rendering, particle effects, and dense modeling. The extension can also be used to create animations by instancing a set of objects with unique attributes that change over time.

To use the ARB_draw_instanced extension, developers must enable it in their application by calling glEnable(GL_ARB_draw_instanced). They then need to create the necessary vertex shader inputs and uniforms and specify the instance data in the vertex data stream. Aside from complex rendering and animations, the ARB_draw_instanced extension can also be used for debugging models and animating technical objects in computer graphics and CAD.