blend-state
GPU-accelerated rendering » GPU state

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Vocabulary
gpu.state

Class description
The blend-state controls how alpha blending between the current framebuffer contents and newly drawn pixels.

•	The constant-color slot contains an optional four-float sequence that specifies a constant parameter to the func-*constant* blend-functions. If constant blend functions are not used, the slot can be f.
•	The rgb-mode and alpha-mode slots both contain blend-mode values that determine the blending equation used between RGB and alpha channel values, respectively. If both slots are f, blending is disabled.

See also
<blend-state>, get-blend-state

Definition

USING: sequences ;

IN: gpu.state

TUPLE: blend-state
    { constant-color sequence read-only initial: f }
    { rgb-mode maybe{ blend-mode } read-only initial: f }
    { alpha-mode maybe{ blend-mode } read-only initial: f } ;

Methods

USING: accessors combinators gpu.state gpu.state.private kernel
opengl.gl sequences ;

M: blend-state set-gpu-state*
    [ ] [ rgb-mode>> ] [ alpha-mode>> ] tri or [
        GL_BLEND glEnable
        [ constant-color>> [ first4 glBlendColor ] when* ] [
            [ rgb-mode>> ] [ alpha-mode>> ] bi {
                [
                    [ equation>> gl-blend-equation ] bi@
                    glBlendEquationSeparate
                ]
                [
                    [ ~quotation~ ~quotation~ bi ] bi@
                    glBlendFuncSeparate
                ]
            } 2cleave
        ] bi
    ] [ drop GL_BLEND glDisable ] if ;