multisample-state
GPU-accelerated rendering » GPU state

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Vocabulary
gpu.state

Class description
The multisample-state controls whether and how multisampling occurs.

•	The multisample? slot is a boolean value that determines whether multisampling is enabled.
•	The sample-alpha-to-coverage? slot is a boolean value that determines whether sample coverage values are determined from their alpha components.
•	The sample-alpha-to-one? slot is a boolean value that determines whether a sample's alpha value is replaced with one after its alpha-based coverage is calculated.
•	The sample-coverage slot is an optional float value that is used to calculate another coverage value that is then combined with the alpha-based coverage. If f, the alpha-based coverage is untouched.
•	The invert-sample-coverage? slot is a boolean value that, if true, indicates that the coverage value derived from sample-coverage should be inverted before being combined.

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

Definition

USING: kernel math ;

IN: gpu.state

TUPLE: multisample-state
    { multisample? boolean read-only initial: f }
    { sample-alpha-to-coverage? boolean read-only initial: f }
    { sample-alpha-to-one? boolean read-only initial: f }
    { sample-coverage maybe{ float } read-only initial: f }
    { invert-sample-coverage? boolean read-only initial: f } ;

Methods

USING: accessors alien.c-types combinators gpu.state kernel
opengl.gl ;

M: multisample-state set-gpu-state*
    dup multisample?>> [
        GL_MULTISAMPLE glEnable {
            [
                GL_SAMPLE_ALPHA_TO_COVERAGE swap
                sample-alpha-to-coverage?>>
                [ glEnable ] [ glDisable ] if
            ]
            [
                GL_SAMPLE_ALPHA_TO_ONE swap
                sample-alpha-to-one?>>
                [ glEnable ] [ glDisable ] if
            ]
            [
                GL_SAMPLE_COVERAGE swap
                [ invert-sample-coverage?>> >c-bool ]
                [ sample-coverage>> ] bi
                [ swap glSampleCoverage glEnable ]
                [ drop glDisable ] if*
            ]
        } cleave
    ] [ drop GL_MULTISAMPLE glDisable ] if ;