GLCOLORWRITEMASK

GLCOLORWRITEMASK is a function in the OpenGL graphics API used to control which components of a fragment's color are written to the currently bound framebuffer. It allows developers to selectively enable or disable writing to the red, green, blue, and alpha color channels.

The function takes a single argument, a boolean value, which is a bitmask. This bitmask is composed of four predefined constants: GL_RED, GL_GREEN, GL_BLUE, and GL_ALPHA. By combining these constants using a bitwise OR operation, developers can specify which channels should be writable. For example, calling glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE) enables writing to all four color components. Conversely, calling glColorMask(GL_FALSE, GL_TRUE, GL_TRUE, GL_TRUE) would disable writing to the red channel while allowing writes to green, blue, and alpha.

This functionality is useful for various rendering techniques. It can be employed to perform color channel separation, for instance, rendering only a grayscale version of an image by disabling the red, green, and blue channels and only writing to alpha, or vice-versa. It can also be used in multi-pass rendering algorithms where different passes might operate on specific color components. By default, all color channels are enabled for writing.