glViewportIndexedf1

glViewportIndexedf1 is not a standard OpenGL function name. The function you are looking for is glViewportIndexedf, which is defined as part of the per-viewport (viewport array) functionality introduced by the ARB_viewport_array extension and is available in core OpenGL 4.1 and later.

glViewportIndexedf sets the viewport for a specific viewport index. Its signature is void glViewportIndexedf(GLuint index, GLfloat x, GLfloat y, GLfloat w, GLfloat h). The index selects which entry in the viewport array is modified, while x and y specify the lower-left corner of the viewport in window coordinates, and w and h specify its width and height in window coordinates. This enables rendering to multiple viewports in a single pass, which is useful for tiled or multi-view rendering scenarios.

Typical usage involves configuring multiple viewports with separate rectangles, for example for split-screen layouts or tiled rendering. The values of x, y, w, and h are interpreted in the current window’s coordinate space, and the range is constrained by the implementation’s viewport limits. The number of supported viewports is queryable via GL_MAX_VIEWPORTS.

glViewportIndexedf is often used in conjunction with other per-viewport commands such as glScissorIndexed to enable per-viewport scissoring. It also collaborates with functions like glViewportArrayv and glViewportIndexedfv, which operate on arrays of viewports. If a context does not support the viewport array extension, glViewportIndexedf will be unavailable.

In summary, glViewportIndexedf provides fine-grained control over individual viewports in multi-viewport rendering, enabling flexible layouts and advanced rendering techniques when supported by the OpenGL context.