glBlendFuncGLONE

glBlendFuncGLONE refers to using the OpenGL blend factor GL_ONE as the source factor in the blending function glBlendFunc. In OpenGL, color blending combines a fragment’s source color with the color already stored in the framebuffer using two factors: sfactor for the source and dfactor for the destination. GL_ONE is a blending factor that represents the value 1.0, meaning the corresponding color component is not scaled.

Usage and behavior: glBlendFunc takes two factors, such that the resulting color is (sfactor * source) + (dfactor * destination). When GL_ONE is used as the source factor, the source color is added to the result without multiplication by its own alpha. Examples include:

- glBlendFunc(GL_ONE, GL_ZERO): the source completely overwrites the destination (no blending).

- glBlendFunc(GL_ONE, GL_ONE): additive blending, where the source color is added to the destination.

- glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA): a form of compositing where the source is fully added while the destination is attenuated by (1 − source alpha). For standard (non-premultiplied) alpha blending, GL_SRC_ALPHA is commonly used as the source factor instead.

Notes: GL_ONE can be used with premultiplied or non-premultiplied alpha contexts, but its effect depends on the chosen destination factor. When blending is enabled (glEnable(GL_BLEND)), glBlendFunc controls how fragments contribute to the framebuffer, and changes persist until the function is called again. For more control, glBlendFuncSeparate allows different factors for color and alpha components.

See also: glBlendFunc, GL_ONE, GL_SRC_ALPHA, additive blending, premultiplied alpha, glBlendFuncSeparate.